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<!-- DFIN ActiveDisclosure(SM) XBRL Schema Document - http://www.dfinsolutions.com/ -->
<!-- Creation Date      : 2022-03-10T16:28:15.5465256+00:00 -->
<!-- Version            : 5.0.1.728 -->
<!-- Package ID         : 558af53d9838426fbe84363d2fd028b6 -->
<!-- Copyright (c) 2022 Donnelley Financial Solutions, Inc. All Rights Reserved. -->
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  <xsd:element id="smhi_BostonPutfordOffshoreSafetyLimitedMember" name="BostonPutfordOffshoreSafetyLimitedMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_ERRVFleetBusinessMember" name="ERRVFleetBusinessMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_NatureOfOperationAndAccountingPoliciesAbstract" name="NatureOfOperationAndAccountingPoliciesAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_WarrantsAndRightsTextBlock" name="WarrantsAndRightsTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_NotesToFinancialStatementsAbstract" name="NotesToFinancialStatementsAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_DeferredGainsPolicyTextBlock" name="DeferredGainsPolicyTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_ScheduleOfCashCashEquivalentsAndRestrictedCashTableTextBlock" name="ScheduleOfCashCashEquivalentsAndRestrictedCashTableTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_OSVPartnersMember" name="OSVPartnersMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SheduleOfVesselAcquiredAndDisposedOfTableTextBlock" name="SheduleOfVesselAcquiredAndDisposedOfTableTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_LesseeOperatingAndFinanceLeaseLiabilityMaturityTableTextBlock" name="LesseeOperatingAndFinanceLeaseLiabilityMaturityTableTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_ScheduleOfSupplementalCashFlowInformationRelatedToLeasesTableTextBlock" name="ScheduleOfSupplementalCashFlowInformationRelatedToLeasesTableTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_ScheduleOfOtherInformationRelatedToLeasesTableTextBlock" name="ScheduleOfOtherInformationRelatedToLeasesTableTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_ScheduleOfNoncontrollingInterestTableTextBlock" name="ScheduleOfNoncontrollingInterestTableTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_ScheduleIIValuationAndQualifyingAccountsTableTextBlock" name="ScheduleIIValuationAndQualifyingAccountsTableTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" name="NatureOfOperationsAndAccountingPoliciesLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_NatureOfOperationsAndAccountingPoliciesTable" name="NatureOfOperationsAndAccountingPoliciesTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_AfricaAndEuropeMember" name="AfricaAndEuropeMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_MiddleEastAndAsiaMember" name="MiddleEastAndAsiaMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_MexMarMember" name="MexMarMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SEACORMarineInternationalLLCMember" name="SEACORMarineInternationalLLCMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_OVHMember" name="OVHMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_CMEMember" name="CMEMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SubsidiariesOfCMEMember" name="SubsidiariesOfCMEMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SEACORMarineForeignHoldingsMember" name="SEACORMarineForeignHoldingsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_PrepaidCharterModificationAndReservationMember" name="PrepaidCharterModificationAndReservationMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_PrepaidVesselManagementFeesMember" name="PrepaidVesselManagementFeesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_ContractCompletionsAndCertainReclassificationsMember" name="ContractCompletionsAndCertainReclassificationsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_OffshoreSupportVesselsMember" name="OffshoreSupportVesselsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_EmergencyResponseAndRescueVesselMember" name="EmergencyResponseAndRescueVesselMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_LiftboatVesselsMember" name="LiftboatVesselsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_AnchorHandlingTowingSupplyVesselMember" name="AnchorHandlingTowingSupplyVesselMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SpecialtyVesselMember" name="SpecialtyVesselMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_VesselUnderConstructionMember" name="VesselUnderConstructionMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_ChangeInAccountingPrincipleForEquipmentOfficeAndLandLeasesMember" name="ChangeInAccountingPrincipleForEquipmentOfficeAndLandLeasesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_ChangeInAccountingPrincipleForUnamortizedDeferredGainsMember" name="ChangeInAccountingPrincipleForUnamortizedDeferredGainsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_NumberOfVessels" name="NumberOfVessels" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="smhi_NumberOfVesselsOwned" name="NumberOfVesselsOwned" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="smhi_NumberOfVesselsLeasedIn" name="NumberOfVesselsLeasedIn" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="smhi_NumberOfVesselsManagedIn" name="NumberOfVesselsManagedIn" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="smhi_NumberOfVesselsJointVentured" name="NumberOfVesselsJointVentured" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="smhi_OffshoreSupportVesselsAnchorHandlingTowingSupplyMember" name="OffshoreSupportVesselsAnchorHandlingTowingSupplyMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_FastSupportVesselsMember" name="FastSupportVesselsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_OffshoreSupportVesselsSupplyMember" name="OffshoreSupportVesselsSupplyMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_OffshoreSupportVesselsSpecialtyMember" name="OffshoreSupportVesselsSpecialtyMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_OffshoreSupportVesselsLiftboatsMember" name="OffshoreSupportVesselsLiftboatsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_GeneralMachineryAndSparesMember" name="GeneralMachineryAndSparesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_CrewTransferVesselsMember" name="CrewTransferVesselsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_CarryingValueOfAssetsHeldForSale" name="CarryingValueOfAssetsHeldForSale" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_NetProceedsFromSaleOfAssets" name="NetProceedsFromSaleOfAssets" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_TransactionCosts" name="TransactionCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_PartialImpairmentOfRightToUseAssets" name="PartialImpairmentOfRightToUseAssets" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_AdditionalImpairmentOfRightToUseAssets" name="AdditionalImpairmentOfRightToUseAssets" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_ReclassOfGainToRetainedEarnings" name="ReclassOfGainToRetainedEarnings" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_DeferredGainOnSaleOfPropertyOtherAdjustments" name="DeferredGainOnSaleOfPropertyOtherAdjustments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_TransformationPlanMember" name="TransformationPlanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SeveranceCharges" name="SeveranceCharges" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_AfricaAndEuropeContinuingOperationsMember" name="AfricaAndEuropeContinuingOperationsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_NoteToFinancialStatementDetailsTextual" name="NoteToFinancialStatementDetailsTextual" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_MergerAgreementMember" name="MergerAgreementMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_MergerConsiderationMember" name="MergerConsiderationMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_PaymentInKindPIKLoanMember" name="PaymentInKindPIKLoanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_PlatformSupplyVesselsMember" name="PlatformSupplyVesselsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SEACOROffshoreDeltaLLCMember" name="SEACOROffshoreDeltaLLCMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SEACOROffshoreAsiaMember" name="SEACOROffshoreAsiaMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SaleAndPurchaseAgreementMember" name="SaleAndPurchaseAgreementMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_DeferredPurchaseAgreementsMember" name="DeferredPurchaseAgreementsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_BusinessCombinationAssumedAndGuaranteeAmount" name="BusinessCombinationAssumedAndGuaranteeAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_DebtInstrumentQuarterlyPrincipalPayments" name="DebtInstrumentQuarterlyPrincipalPayments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_PercentageOfInterestAccruesUnderCreditFacilityPlusMandatoryCost" name="PercentageOfInterestAccruesUnderCreditFacilityPlusMandatoryCost" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_AverageAgeOfVessels" name="AverageAgeOfVessels" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetCostBasisForPurchase" name="BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetCostBasisForPurchase" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_PurchasePricePayableForEquityMethodInvestment" name="PurchasePricePayableForEquityMethodInvestment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_BusinessCombinationPurchasePricePayableToSellersAtClosingOfTransaction" name="BusinessCombinationPurchasePricePayableToSellersAtClosingOfTransaction" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_BusinessAcquisitionPurchasePriceForMembershipInterestsAnnualInstallmentPaymentInYearOne" name="BusinessAcquisitionPurchasePriceForMembershipInterestsAnnualInstallmentPaymentInYearOne" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_BusinessAcquisitionPurchasePriceForMembershipInterestsAnnualInstallmentPaymentInYearTwo" name="BusinessAcquisitionPurchasePriceForMembershipInterestsAnnualInstallmentPaymentInYearTwo" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_BusinessAcquisitionPurchasePriceForMembershipInterestsAnnualInstallmentPaymentInYearThree" name="BusinessAcquisitionPurchasePriceForMembershipInterestsAnnualInstallmentPaymentInYearThree" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_BusinessAcquisitionPurchasePriceForMembershipInterestsAnnualInstallmentPaymentInYearFour" name="BusinessAcquisitionPurchasePriceForMembershipInterestsAnnualInstallmentPaymentInYearFour" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_BusinessAcquisitionPercentageOfPurchasePriceFixedAccruedInterestRateForMembershipInterestInYearOne" name="BusinessAcquisitionPercentageOfPurchasePriceFixedAccruedInterestRateForMembershipInterestInYearOne" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="smhi_BusinessAcquisitionPercentageOfPurchasePriceFixedAccruedInterestRateForMembershipInterestInYearTwo" name="BusinessAcquisitionPercentageOfPurchasePriceFixedAccruedInterestRateForMembershipInterestInYearTwo" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="smhi_BusinessAcquisitionPercentageOfPurchasePriceFixedAccruedInterestRateForMembershipInterestInYearThree" name="BusinessAcquisitionPercentageOfPurchasePriceFixedAccruedInterestRateForMembershipInterestInYearThree" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="smhi_BusinessAcquisitionPercentageOfPurchasePriceFixedAccruedInterestRateForMembershipInterestInYearFour" name="BusinessAcquisitionPercentageOfPurchasePriceFixedAccruedInterestRateForMembershipInterestInYearFour" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="smhi_BusinessAcquisitionPurchasePriceAmortizationPeriod" name="BusinessAcquisitionPurchasePriceAmortizationPeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_NumberOfVesselsDeliveredToCompany" name="NumberOfVesselsDeliveredToCompany" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="smhi_NumberOfVesselsOwnedWithHighSpecification" name="NumberOfVesselsOwnedWithHighSpecification" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="smhi_NumberOfVesselsOwnedWithIdenticalSpecification" name="NumberOfVesselsOwnedWithIdenticalSpecification" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="smhi_CapitalExpendituresAndPaymentsOnEquipment" name="CapitalExpendituresAndPaymentsOnEquipment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_VesselUnderConstructionAndOtherEquipmentMember" name="VesselUnderConstructionAndOtherEquipmentMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_PlatformSupplyVesselsAndFastSupportVesselsMember" name="PlatformSupplyVesselsAndFastSupportVesselsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_FalconGlobalUSATermLoanFacilityMember" name="FalconGlobalUSATermLoanFacilityMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_VesselsMember" name="VesselsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_NorthSeaERRVFleetMember" name="NorthSeaERRVFleetMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_LiftboatsMember" name="LiftboatsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_NumberOfEquipmentAcquired" name="NumberOfEquipmentAcquired" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_NumberOfEquipmentHeldForSaleExcludedFromDeliveriesOfOffshoreSupportVessels" name="NumberOfEquipmentHeldForSaleExcludedFromDeliveriesOfOffshoreSupportVessels" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_NumberOfEquipmentAcquiredExcludedFromDeliveriesOfOffshoreSupportVessels" name="NumberOfEquipmentAcquiredExcludedFromDeliveriesOfOffshoreSupportVessels" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_NumberOfAdditionalJointVenturesHeldInterests" name="NumberOfAdditionalJointVenturesHeldInterests" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_ProceedsFromSaleOfPropertyPlantAndEquipmentGross" name="ProceedsFromSaleOfPropertyPlantAndEquipmentGross" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_PaymentsForTransactionsFeesAndOtherCosts" name="PaymentsForTransactionsFeesAndOtherCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_CashSoldOnPropertyPlantAndEquipmentDisposal" name="CashSoldOnPropertyPlantAndEquipmentDisposal" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_ProceedsFromPropertyPlantAndEquipmentIncludingDepositsAndGainOnSale" name="ProceedsFromPropertyPlantAndEquipmentIncludingDepositsAndGainOnSale" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_NumberOfEquipmentSold" name="NumberOfEquipmentSold" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_ProceedsFromDeposits" name="ProceedsFromDeposits" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_ReducedOfDebtUnderCreditFacility" name="ReducedOfDebtUnderCreditFacility" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_PropertyPlantEquipmentConsiderationTransferred" name="PropertyPlantEquipmentConsiderationTransferred" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_DisposalGroupIncludingDiscontinuedOperationMaximumAdditionalConsideration" name="DisposalGroupIncludingDiscontinuedOperationMaximumAdditionalConsideration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_ProceedsFromSaleOfPropertyPlantAndEquipmentIncludingDeposits" name="ProceedsFromSaleOfPropertyPlantAndEquipmentIncludingDeposits" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_ProceedsFromSaleOfPropertyPlantAndEquipmentExcludingDepositsForFutureVesselSales" name="ProceedsFromSaleOfPropertyPlantAndEquipmentExcludingDepositsForFutureVesselSales" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_NumberOfEquipmentRemovedFromService" name="NumberOfEquipmentRemovedFromService" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_NumberOfEquipmentRemovedFromServiceExcludesFromMajorEquipmentDispositions" name="NumberOfEquipmentRemovedFromServiceExcludesFromMajorEquipmentDispositions" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_NumberOfEquipmentHeldForSaleExcludedFromMajorEquipmentDispositions" name="NumberOfEquipmentHeldForSaleExcludedFromMajorEquipmentDispositions" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_SEACORMarlinLLCMember" name="SEACORMarlinLLCMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_MEXMAROffshoreMember" name="MEXMAROffshoreMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_OffshoreVesselHoldingsMember" name="OffshoreVesselHoldingsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_OtherOffshoreMarineServicesJointVenturesMember" name="OtherOffshoreMarineServicesJointVenturesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_AllOtherExcludingMexMarFalconGlobalSeaCatCrewzerAndSeaCatCrewzerIIMember" name="AllOtherExcludingMexMarFalconGlobalSeaCatCrewzerAndSeaCatCrewzerIIMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_MexmarOffshoreInternationalMember" name="MexmarOffshoreInternationalMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_EquityMethodInvestmentSummarizedFinancialInformationOperatingAndAdministrative" name="EquityMethodInvestmentSummarizedFinancialInformationOperatingAndAdministrative" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_EquityMethodInvestmentSummarizedFinancialInformationDepreciation" name="EquityMethodInvestmentSummarizedFinancialInformationDepreciation" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_EquityMethodInvestmentSummarizedFinancialInformationOperatingCostsAndExpenses" name="EquityMethodInvestmentSummarizedFinancialInformationOperatingCostsAndExpenses" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_EquityMethodInvestmentSummarizedFinancialInformationIncomeLossOnAssetDispositionsAndImpairmentsNet" name="EquityMethodInvestmentSummarizedFinancialInformationIncomeLossOnAssetDispositionsAndImpairmentsNet" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_EquityMethodInvestmentsUnrealizedIntercompanyProfitLossNotEliminatedAmount" name="EquityMethodInvestmentsUnrealizedIntercompanyProfitLossNotEliminatedAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_UPOffshoresMember" name="UPOffshoresMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_OffshoreVesselHoldingsAndOperadoraProductoraYExploradoraMexicanaSADeCVMember" name="OffshoreVesselHoldingsAndOperadoraProductoraYExploradoraMexicanaSADeCVMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_JackUpDrillingsMember" name="JackUpDrillingsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_FSVOffshoreSupportVesselsMember" name="FSVOffshoreSupportVesselsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_NumberOfEquipmentOperated" name="NumberOfEquipmentOperated" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_EquityMethodInvestmentOwnershipPercentSold" name="EquityMethodInvestmentOwnershipPercentSold" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_NumberOfVesselSold" name="NumberOfVesselSold" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_PercentageOfGainFromEquityEarnings" name="PercentageOfGainFromEquityEarnings" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_EquityMethodInvestmentOwnershipPercentageTransferred" name="EquityMethodInvestmentOwnershipPercentageTransferred" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="smhi_EquityInterestTransferredConsiderationAndTransactionFee" name="EquityInterestTransferredConsiderationAndTransactionFee" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_DebtInstrumentForgivenessOfAccruedInterest" name="DebtInstrumentForgivenessOfAccruedInterest" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_FinancingAgreement" name="FinancingAgreement" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_ReturnOfCapitalEquityMethodInvestment" name="ReturnOfCapitalEquityMethodInvestment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_ConstructionReserveFundsCommitmentPeriod" name="ConstructionReserveFundsCommitmentPeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_NumberOfExtensionPeriod" name="NumberOfExtensionPeriod" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_ConstructionReserveFundsExtensionPeriod" name="ConstructionReserveFundsExtensionPeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_ShortTermConstructionReserveFunds" name="ShortTermConstructionReserveFunds" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_ConstructionReserveFundWithdrawals" name="ConstructionReserveFundWithdrawals" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_CumulativeEffectOnRetainedEarningsBeforeTax" name="CumulativeEffectOnRetainedEarningsBeforeTax" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_CumulativeEffectOnRetainedEarningsTax" name="CumulativeEffectOnRetainedEarningsTax" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_OtherEquipmentMember" name="OtherEquipmentMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_NumberOfOperatingLeasesOnEquipment" name="NumberOfOperatingLeasesOnEquipment" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_FinanceLeaseCostsAbstract" name="FinanceLeaseCostsAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_NumberOfOperatingLeasesImpaired" name="NumberOfOperatingLeasesImpaired" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_ConvertibleSeniorNotesMember" name="ConvertibleSeniorNotesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SEACORMarineForeignHoldingsCreditFacilityMember" name="SEACORMarineForeignHoldingsCreditFacilityMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SeaCatCrewzerIIITermLoanFacilityMember" name="SeaCatCrewzerIIITermLoanFacilityMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SEACOROffshoreDeltaFormerlyKnownAsSEACOSCOAcquisitionDebtMember" name="SEACOROffshoreDeltaFormerlyKnownAsSEACOSCOAcquisitionDebtMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SEACORDeltaFormerlyKnownAsSEACOSCOShipyardFinancingMember" name="SEACORDeltaFormerlyKnownAsSEACOSCOShipyardFinancingMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SEACORAlpineShipyardFinancingMember" name="SEACORAlpineShipyardFinancingMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SEACOR88888TermLoanMember" name="SEACOR88888TermLoanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_TarahumaraShipyardFinancingMember" name="TarahumaraShipyardFinancingMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SeacorOffshoreOSVMember" name="SeacorOffshoreOSVMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_FalconGlobalUSARevolverMember" name="FalconGlobalUSARevolverMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_WindcatWorkboatsFacilitiesMember" name="WindcatWorkboatsFacilitiesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SEACOSCOOffshoreLLCMember" name="SEACOSCOOffshoreLLCMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_LineOfCreditFacilityAssumedAndGuaranteed" name="LineOfCreditFacilityAssumedAndGuaranteed" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_TermLoanToAcquireOneVesselMember" name="TermLoanToAcquireOneVesselMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_ConditionalPayoffAgreementMember" name="ConditionalPayoffAgreementMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_TermAndRevolvingLoanFacilityMember" name="TermAndRevolvingLoanFacilityMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_LoanFacilityWithDNBBankASAMember" name="LoanFacilityWithDNBBankASAMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_OtherDNBCreditFacilitiesMember" name="OtherDNBCreditFacilitiesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_TaxRefundAndIndemnificationAgreementMember" name="TaxRefundAndIndemnificationAgreementMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_ConvertibleSeniorNotes375PercentMember" name="ConvertibleSeniorNotes375PercentMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_CarlyleWarrantsMember" name="CarlyleWarrantsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_ThreePointSevenFivePercentageConvertibleNotesMember" name="ThreePointSevenFivePercentageConvertibleNotesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_ConvertibleSeniorNotesConvertedToWarrantsMember" name="ConvertibleSeniorNotesConvertedToWarrantsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_CarlyleGroupMember" name="CarlyleGroupMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_TermLoanToAcquireTwoVesselsMember" name="TermLoanToAcquireTwoVesselsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_LongtermDebtObligationMember" name="LongtermDebtObligationMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_DebtInstrumentMaturityYear" name="DebtInstrumentMaturityYear" type="xbrli:gYearItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_NumberOfLiftboatsReleasedFromMortgagesAndSecurityArrangements" name="NumberOfLiftboatsReleasedFromMortgagesAndSecurityArrangements" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="smhi_ReimbursementAmount" name="ReimbursementAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_HullAndMachineryInsuranceProceeds" name="HullAndMachineryInsuranceProceeds" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_TroubledDebtRestructuringDebtorCurrentPeriodIncreaseDecreaseOfBasicEarningsPerShare" name="TroubledDebtRestructuringDebtorCurrentPeriodIncreaseDecreaseOfBasicEarningsPerShare" type="dtr-types:perShareItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_TroubledDebtRestructuringDebtorCurrentPeriodIncreaseDecreaseOfDilutedEarningsPerShare" name="TroubledDebtRestructuringDebtorCurrentPeriodIncreaseDecreaseOfDilutedEarningsPerShare" type="dtr-types:perShareItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_DebtInstrumentPercentageOfFinancingOnTotalPurchasePrice" name="DebtInstrumentPercentageOfFinancingOnTotalPurchasePrice" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="smhi_DebtInstrumentExtendedMaturityDate" name="DebtInstrumentExtendedMaturityDate" type="xbrli:dateItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_ApplicationFeePaidInConjunctionWithAmendmentAndAmortizedOverCreditFacilityTerm" name="ApplicationFeePaidInConjunctionWithAmendmentAndAmortizedOverCreditFacilityTerm" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_PurchasePricePayableForEquityMethodInvestmentInYearOne" name="PurchasePricePayableForEquityMethodInvestmentInYearOne" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_PurchasePricePayableForEquityMethodInvestmentInYearTwo" name="PurchasePricePayableForEquityMethodInvestmentInYearTwo" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_PurchasePricePayableForEquityMethodInvestmentInYearThree" name="PurchasePricePayableForEquityMethodInvestmentInYearThree" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_PurchasePricePayableForEquityMethodInvestmentInYearFour" name="PurchasePricePayableForEquityMethodInvestmentInYearFour" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_PercentageOfPurchasePriceFixedAccruedInterestRateForEquityMethodInvestmentInYearOne" name="PercentageOfPurchasePriceFixedAccruedInterestRateForEquityMethodInvestmentInYearOne" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="smhi_PercentageOfPurchasePriceFixedAccruedInterestRateForEquityMethodInvestmentInYearTwo" name="PercentageOfPurchasePriceFixedAccruedInterestRateForEquityMethodInvestmentInYearTwo" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="smhi_PercentageOfPurchasePriceFixedAccruedInterestRateForEquityMethodInvestmentInYearThree" name="PercentageOfPurchasePriceFixedAccruedInterestRateForEquityMethodInvestmentInYearThree" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="smhi_PercentageOfPurchasePriceFixedAccruedInterestRateForEquityMethodInvestmentInYearFour" name="PercentageOfPurchasePriceFixedAccruedInterestRateForEquityMethodInvestmentInYearFour" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="smhi_EquityMethodInvestmentPurchasePriceAmortizationPeriod" name="EquityMethodInvestmentPurchasePriceAmortizationPeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_DebtInstrumentMaturityPeriod" name="DebtInstrumentMaturityPeriod" type="xbrli:gYearItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_NumberOfAdditionalVesselsOwned" name="NumberOfAdditionalVesselsOwned" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="smhi_EstimatedCashOrCashEquivalentsTaxRefundsReceivable" name="EstimatedCashOrCashEquivalentsTaxRefundsReceivable" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_ClaimsRecoverableUnderBorrowingsPercentageOfObligationsOutstanding" name="ClaimsRecoverableUnderBorrowingsPercentageOfObligationsOutstanding" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_ClaimsRecoverableAmountUnderBorrowings" name="ClaimsRecoverableAmountUnderBorrowings" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_InterestReceivedOnCashRefunds" name="InterestReceivedOnCashRefunds" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_IncomeTaxesLineItems" name="IncomeTaxesLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_IncomeTaxesTable" name="IncomeTaxesTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_PercentageOfNetOperatingLossesFacilitateTaxSavings" name="PercentageOfNetOperatingLossesFacilitateTaxSavings" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_TransactionFee" name="TransactionFee" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_CashTaxRefundsWithoutRestrictionsToUse" name="CashTaxRefundsWithoutRestrictionsToUse" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_CashTaxRefundsWithRestrictionsToUse" name="CashTaxRefundsWithRestrictionsToUse" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_EliminationsMember" name="EliminationsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_IncreaseDecreaseInTransitionTaxLiability" name="IncreaseDecreaseInTransitionTaxLiability" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_EffectiveIncomeTaxRateReconciliationJVEquityEarnings" name="EffectiveIncomeTaxRateReconciliationJVEquityEarnings" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_EffectiveIncomeTaxRateReconciliationReturnToProvision" name="EffectiveIncomeTaxRateReconciliationReturnToProvision" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_EffectiveIncomeTaxRateReconciliationSubpartFIncome" name="EffectiveIncomeTaxRateReconciliationSubpartFIncome" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_EffectiveIncomeTaxRateReconciliationShareAwardPlans" name="EffectiveIncomeTaxRateReconciliationShareAwardPlans" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_OperatingLossCarryforwardsExpirationPeriod" name="OperatingLossCarryforwardsExpirationPeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_InterestExpenseSuspendedDeductible" name="InterestExpenseSuspendedDeductible" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_InterestExpenseSuspended" name="InterestExpenseSuspended" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_InterestExpenseSuspendedLimitationPercentage" name="InterestExpenseSuspendedLimitationPercentage" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_OperatingLossCarryforwardsPercentageOfTaxableIncomeUtilizationLimitation" name="OperatingLossCarryforwardsPercentageOfTaxableIncomeUtilizationLimitation" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_InterestExpenseCarryforward" name="InterestExpenseCarryforward" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_InterestRateSwapAgreementThreePointThreeTwoPercentMember" name="InterestRateSwapAgreementThreePointThreeTwoPercentMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_InterestRateSwapAgreementThreePointOneNineFivePercentMember" name="InterestRateSwapAgreementThreePointOneNineFivePercentMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SEACOR88888Member" name="SEACOR88888Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_WindcatWorkboatsLtdMember" name="WindcatWorkboatsLtdMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_DerivativesNotionalAmount" name="DerivativesNotionalAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="smhi_StatementStatementNote9DerivativeInstrumentsAndHedgingStrategiesEffectOfDerivativeInstrumentsOnOtherComprehensiveIncomeLossDetails" name="StatementStatementNote9DerivativeInstrumentsAndHedgingStrategiesEffectOfDerivativeInstrumentsOnOtherComprehensiveIncomeLossDetails" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_JointVentureInterestRateSwapMember" name="JointVentureInterestRateSwapMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_StatementStatementNote9DerivativeInstrumentsAndHedgingStrategiesGainsLossesOnDerivativeInstrumentsDetails" name="StatementStatementNote9DerivativeInstrumentsAndHedgingStrategiesGainsLossesOnDerivativeInstrumentsDetails" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_ProceedsToBeReceivedFromSaleOfBusiness" name="ProceedsToBeReceivedFromSaleOfBusiness" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_NumberOfPropertyAndEquipmentWithFairValue" name="NumberOfPropertyAndEquipmentWithFairValue" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_SeabulkTimsIAndOffshoreVesselHoldingsMember" name="SeabulkTimsIAndOffshoreVesselHoldingsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_NumberOfInvestmentsAtEquityInFiftyPercentOrLessOwnedCompaniesMarkedZeroDueToReturnOfFundsThatExceededTheCarryingValueInvestmentAndContinuedLosses" name="NumberOfInvestmentsAtEquityInFiftyPercentOrLessOwnedCompaniesMarkedZeroDueToReturnOfFundsThatExceededTheCarryingValueInvestmentAndContinuedLosses" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_InvestmentOwnedExcessAmountFairValue" name="InvestmentOwnedExcessAmountFairValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_ClassOfWarrantOrRightExercisedDuringPeriod" name="ClassOfWarrantOrRightExercisedDuringPeriod" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_StockIssuedDuringPeriodSharesWarrantsExercisedSharesWithHeldAsPaymentOfExercise" name="StockIssuedDuringPeriodSharesWarrantsExercisedSharesWithHeldAsPaymentOfExercise" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_WarrantsTransactionsMember" name="WarrantsTransactionsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_OSVPartnersOneMember" name="OSVPartnersOneMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_ExchangeWarrantsMember" name="ExchangeWarrantsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_TwoThousandSeventeenEquityIncentivePlanMember" name="TwoThousandSeventeenEquityIncentivePlanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_TwoThousandTwentyEquityIncentivePlanMember" name="TwoThousandTwentyEquityIncentivePlanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_FalconGlobalHoldingMember" name="FalconGlobalHoldingMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SeabulkOverseasMember" name="SeabulkOverseasMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_VEESEAHoldingsIncMember" name="VEESEAHoldingsIncMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_PensionAndOtherPostretirementBenefitsDisclosureLineItems" name="PensionAndOtherPostretirementBenefitsDisclosureLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_PensionAndOtherPostretirementBenefitsDisclosureTable" name="PensionAndOtherPostretirementBenefitsDisclosureTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_OtherDefinedContributionPlanMember" name="OtherDefinedContributionPlanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_PercentageOfNumberOfCommonStockSharesOutstanding" name="PercentageOfNumberOfCommonStockSharesOutstanding" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_EquityIncentivePlan2017Member" name="EquityIncentivePlan2017Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_EquityIncentivePlan2017And2020Member" name="EquityIncentivePlan2017And2020Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_PerformanceRestrictedStockUnitsMember" name="PerformanceRestrictedStockUnitsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_EmployeeStockPurchasePlanMember" name="EmployeeStockPurchasePlanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_TwoThousandSeventeenAndTwoThousandTwentyPlanMember" name="TwoThousandSeventeenAndTwoThousandTwentyPlanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_PaymentsForDistributionOfRestrictedStockSpinOff" name="PaymentsForDistributionOfRestrictedStockSpinOff" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_DistributionOfRestrictedStockInConnectionWithSpinoff" name="DistributionOfRestrictedStockInConnectionWithSpinoff" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_DirectorStockAwardsMember" name="DirectorStockAwardsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriodBeforeAdjustment" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriodBeforeAdjustment" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPreviousPeriodGross" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPreviousPeriodGross" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_RelatedPartyTransactionsMinimumAmountOfTransactionsForReviewAndApproval" name="RelatedPartyTransactionsMinimumAmountOfTransactionsForReviewAndApproval" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_SEACORHoldingsMember" name="SEACORHoldingsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_TransitionServicesAgreementMember" name="TransitionServicesAgreementMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_NonExecutiveChairmanMember" name="NonExecutiveChairmanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_PresidentChiefExecutiveOfficerAndDirectorMember" name="PresidentChiefExecutiveOfficerAndDirectorMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_ExecutiveVicePresidentAndChiefFinancialOfficerMember" name="ExecutiveVicePresidentAndChiefFinancialOfficerMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_CarolineMember" name="CarolineMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_CarolineIIMember" name="CarolineIIMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_TwoThousandSeventeenPreferredInterestsMember" name="TwoThousandSeventeenPreferredInterestsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_ClassAPreferredInterestsMember" name="ClassAPreferredInterestsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SecondLienDebtMember" name="SecondLienDebtMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_ClassAPreferredInterestsCarolineMember" name="ClassAPreferredInterestsCarolineMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_PIKLoanDebtAndCarolineTwoMember" name="PIKLoanDebtAndCarolineTwoMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_ClassAPreferredInterestsCarolineTwoMember" name="ClassAPreferredInterestsCarolineTwoMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_PIKLoanDebtMember" name="PIKLoanDebtMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_ExchangeMember" name="ExchangeMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_ThirdPartyLenderMember" name="ThirdPartyLenderMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_PrincipalMember" name="PrincipalMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_OSVCreditFacilityMember" name="OSVCreditFacilityMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_PreferredInterestsAndClassAPreferredInterestsMember" name="PreferredInterestsAndClassAPreferredInterestsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_MergerConsiderationAndPaymentInKindLoanConsiderationMember" name="MergerConsiderationAndPaymentInKindLoanConsiderationMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_CMBNVMember" name="CMBNVMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_WarrantsIssuedInPrivatePlacementMember" name="WarrantsIssuedInPrivatePlacementMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_LenderNonRecourseMember" name="LenderNonRecourseMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_OPEMMember" name="OPEMMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SubsidiaryOfMexMarMember" name="SubsidiaryOfMexMarMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_TalosEnergyIncMember" name="TalosEnergyIncMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_InterestReceived" name="InterestReceived" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_TaxRefundsRestrictedCash" name="TaxRefundsRestrictedCash" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_PercentageOfInitialLimitedPartnerInterestsAndGeneralPartnerInterestsAndInitialLpInterestsHeldByUnrelatedThirdParties" name="PercentageOfInitialLimitedPartnerInterestsAndGeneralPartnerInterestsAndInitialLpInterestsHeldByUnrelatedThirdParties" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_EquityMethodInvestmentOwnershipAmount" name="EquityMethodInvestmentOwnershipAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_VesselManagementFees" name="VesselManagementFees" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_LoanAcquired" name="LoanAcquired" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_PercentageSaleOfEquity" name="PercentageSaleOfEquity" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="smhi_PercentageOfConvertibleNotesConvertedIntoCommonStock" name="PercentageOfConvertibleNotesConvertedIntoCommonStock" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_DebtIndebtedness" name="DebtIndebtedness" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_TotalPurchasePrice" name="TotalPurchasePrice" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_GainLossOnEquityEarnings" name="GainLossOnEquityEarnings" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_DistributionReceived" name="DistributionReceived" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_ExcessOfDistributionReceived" name="ExcessOfDistributionReceived" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_BusinessCombinationConsiderationTransferredPercentage" name="BusinessCombinationConsiderationTransferredPercentage" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_LoanInExchange" name="LoanInExchange" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_LoanEarlyRepayment" name="LoanEarlyRepayment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_CommitmentsAndContingenciesLineItems" name="CommitmentsAndContingenciesLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_CommitmentsAndContingenciesTable" name="CommitmentsAndContingenciesTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_DeficiencyNoticeMember" name="DeficiencyNoticeMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_CostAllocationPercentage" name="CostAllocationPercentage" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_NumberOfCustomer" name="NumberOfCustomer" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="smhi_SeacorMarineArabiaLLCMember" name="SeacorMarineArabiaLLCMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_ZamilOffshoreMember" name="ZamilOffshoreMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_TenLargestCustomersMember" name="TenLargestCustomersMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_ExxonMobilMember" name="ExxonMobilMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SaudiAramcoMember" name="SaudiAramcoMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_GeneralAndAdministrativeExpenseIncludingShortTermLeaseExpense" name="GeneralAndAdministrativeExpenseIncludingShortTermLeaseExpense" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_AssetsExcludingCorporateAssets" name="AssetsExcludingCorporateAssets" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_TimeCharterMember" name="TimeCharterMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_BareboatCharterMember" name="BareboatCharterMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_OtherMarineServicesMember" name="OtherMarineServicesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_PersonnelMember" name="PersonnelMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_RepairsAndMaintenanceMember" name="RepairsAndMaintenanceMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_DrydockingMember" name="DrydockingMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_InsuranceAndLossReservesMember" name="InsuranceAndLossReservesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_FuelLubesAndSuppliesMember" name="FuelLubesAndSuppliesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_OtherDirectCostsAndExpensesMember" name="OtherDirectCostsAndExpensesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_DisposalGroupIncludingDiscontinuedOperationIncomeLossBeforeEquityMethodInvestmentsAfterTax" name="DisposalGroupIncludingDiscontinuedOperationIncomeLossBeforeEquityMethodInvestmentsAfterTax" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_DisposalGroupIncludingDiscontinuedOperationIncomeLossFromEquityMethodInvestments" name="DisposalGroupIncludingDiscontinuedOperationIncomeLossFromEquityMethodInvestments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_DisposalGroupIncludingDiscontinuedOperationIncomeLossBeforeIncomeTaxesAndIncomeLossFromEquityMethodInvestments" name="DisposalGroupIncludingDiscontinuedOperationIncomeLossBeforeIncomeTaxesAndIncomeLossFromEquityMethodInvestments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_DisposalGroupIncludingDiscontinuedOperationOtherNonoperatingIncomeExpense" name="DisposalGroupIncludingDiscontinuedOperationOtherNonoperatingIncomeExpense" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_DisposalGroupIncludingDiscontinuedOperationOtherNet" name="DisposalGroupIncludingDiscontinuedOperationOtherNet" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_DisposalGroupIncludingDiscontinuedOperationLeaseExpense" name="DisposalGroupIncludingDiscontinuedOperationLeaseExpense" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_DisposalGroupIncludingDiscontinuedOperationGainLossOnAssetsDispositionAndImpairmentsNet" name="DisposalGroupIncludingDiscontinuedOperationGainLossOnAssetsDispositionAndImpairmentsNet" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_OtherRevenueMember" name="OtherRevenueMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_DisposalGroupIncludingDiscontinuedOperationIncomeTaxExpenseBenefit" name="DisposalGroupIncludingDiscontinuedOperationIncomeTaxExpenseBenefit" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_DisposalGroupDiscontinuedOperationOperatingRevenueAbstract" name="DisposalGroupDiscontinuedOperationOperatingRevenueAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_DisposalGroupDiscontinuedOperationCostsAndExpensesAbstract" name="DisposalGroupDiscontinuedOperationCostsAndExpensesAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_DisposalGroupIncludingDiscontinuedOperationOtherNonoperatingIncomeExpenseAbstract" name="DisposalGroupIncludingDiscontinuedOperationOtherNonoperatingIncomeExpenseAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
</xsd:schema>
