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<!-- DFIN ActiveDisclosure(SM) XBRL Schema Document - http://www.dfinsolutions.com/ -->
<!-- Creation Date      : 2019-11-08T22:17:22.5488095+00:00 -->
<!-- Version            : 5.0.0.208 -->
<!-- Package ID         : 7f02a5996c7e4e8bb7875337d0cb78c9 -->
<!-- Copyright (c) 2019 Donnelley Financial Solutions, Inc. All Rights Reserved. -->
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  <xsd:element id="smhi_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseDiscontinuedOperationsIncludingExchangeRateEffect" name="CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseDiscontinuedOperationsIncludingExchangeRateEffect" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_BasisOfPresentationAndAccountingPoliciesAbstract" name="BasisOfPresentationAndAccountingPoliciesAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_WarrantsAndRightsTextBlock" name="WarrantsAndRightsTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_RecentlyAdoptedAccountingStandardsPolicyTextBlock" name="RecentlyAdoptedAccountingStandardsPolicyTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_DeferredGainsPolicyTextBlock" name="DeferredGainsPolicyTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_ScheduleOfDeferredGainTableTextBlock" name="ScheduleOfDeferredGainTableTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_ScheduleOfCumulativeRestructuringAndReorganizationCostIncurredToDateEstimatedRemainingAndToBeIncurredTableTextBlock" name="ScheduleOfCumulativeRestructuringAndReorganizationCostIncurredToDateEstimatedRemainingAndToBeIncurredTableTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_ScheduleOfOtherInformationRelatedToOperatingLeasesTableTextBlock" name="ScheduleOfOtherInformationRelatedToOperatingLeasesTableTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_ScheduleOfNoncontrollingInterestTableTextBlock" name="ScheduleOfNoncontrollingInterestTableTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_BasisOfPresentationAndAccountingPoliciesLineItems" name="BasisOfPresentationAndAccountingPoliciesLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_BasisOfPresentationAndAccountingPoliciesTable" name="BasisOfPresentationAndAccountingPoliciesTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_ChangeInAccountingPrincipleForEquipmentOfficeAndLandLeasesMember" name="ChangeInAccountingPrincipleForEquipmentOfficeAndLandLeasesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_ChangeInAccountingPrincipleForUnamortizedDeferredGainsMember" name="ChangeInAccountingPrincipleForUnamortizedDeferredGainsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SaleAndPurchaseAgreementMember" name="SaleAndPurchaseAgreementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SEACORCapitalUKLimitedMember" name="SEACORCapitalUKLimitedMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_BostonPutfordOffshoreSafetyLimitedMember" name="BostonPutfordOffshoreSafetyLimitedMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_NorthStarHoldcoLimitedMember" name="NorthStarHoldcoLimitedMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_DeferredReimbursementAndDeferredReservationFeesMember" name="DeferredReimbursementAndDeferredReservationFeesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_TwoCustomersMember" name="TwoCustomersMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <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_ContractWithCustomerLiabilityAdditions" name="ContractWithCustomerLiabilityAdditions" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_CrewTransferVesselsMember" name="CrewTransferVesselsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_AllOtherOffshoreSupportVesselsMember" name="AllOtherOffshoreSupportVesselsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <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="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_MiddleEastAndAsiaMember" name="MiddleEastAndAsiaMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_RestructuringLiability" name="RestructuringLiability" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_PaymentsToAcquirePropertyPlantAndEquipmentIncludingFairValueHedges" name="PaymentsToAcquirePropertyPlantAndEquipmentIncludingFairValueHedges" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_NumberOfEquipmentAcquired" name="NumberOfEquipmentAcquired" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_FastSupportVesselsMember" name="FastSupportVesselsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_PlatformSupplyVesselsMember" name="PlatformSupplyVesselsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_VesselUnderConstructionMember" name="VesselUnderConstructionMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SpecialtyVesselMember" name="SpecialtyVesselMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_AnchorHandlingTowingSupplyMember" name="AnchorHandlingTowingSupplyMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SupplyVesselsMember" name="SupplyVesselsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_LiftboatsMember" name="LiftboatsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <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_ProceedsFromDeposits" name="ProceedsFromDeposits" 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_NumberOfVesselsDeliveredToCompany" name="NumberOfVesselsDeliveredToCompany" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="smhi_NumberOfVesselsForWhichCompanyGetsTitle" name="NumberOfVesselsForWhichCompanyGetsTitle" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="smhi_SeaCoscoOffshoreLLCMember" name="SeaCoscoOffshoreLLCMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SEACOROffshoreAsiaMember" name="SEACOROffshoreAsiaMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_ChinaShippingFanTaiLimitedAndChinaShippingIndustryHongKongCoLimitedMember" name="ChinaShippingFanTaiLimitedAndChinaShippingIndustryHongKongCoLimitedMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_MemorandumOfUnderstandingMember" name="MemorandumOfUnderstandingMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_MexmarOffshoreInternationalMember" name="MexmarOffshoreInternationalMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_FRSWindcatOffshoreLogisticsGmbHMember" name="FRSWindcatOffshoreLogisticsGmbHMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_OtherOffshoreMarineServicesJointVenturesMember" name="OtherOffshoreMarineServicesJointVenturesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_NumberOfVesselsAcquired" name="NumberOfVesselsAcquired" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_AgreementStandstillDate" name="AgreementStandstillDate" type="xbrli:dateItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_LoansReceivableInterestRateStatedPercentage" name="LoansReceivableInterestRateStatedPercentage" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="smhi_ShareholderLoansInRespectOfWorkingCapital" name="ShareholderLoansInRespectOfWorkingCapital" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_InterestIncomeRecognizedOnShareholderLoansInRespectOfWorkingCapital" name="InterestIncomeRecognizedOnShareholderLoansInRespectOfWorkingCapital" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_NumberOfVesselsOwned" name="NumberOfVesselsOwned" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="smhi_EquityMethodInvestmentUnrealizedGainLoss" name="EquityMethodInvestmentUnrealizedGainLoss" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_SaleOfVesselsConsideration" name="SaleOfVesselsConsideration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="smhi_AllocableShareOfUncalledCapital" name="AllocableShareOfUncalledCapital" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_SEACORMarineForeignHoldingsSyndicatedCreditFacilityMember" name="SEACORMarineForeignHoldingsSyndicatedCreditFacilityMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_ConvertibleSeniorNotesMember" name="ConvertibleSeniorNotesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_FalconGlobalUSATermLoanFacilityMember" name="FalconGlobalUSATermLoanFacilityMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SeaCatCrewzerIIITermLoanFacilityMember" name="SeaCatCrewzerIIITermLoanFacilityMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_WindcatWorkboatsFacilitiesMember" name="WindcatWorkboatsFacilitiesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_FalconGlobalUSARevolverMember" name="FalconGlobalUSARevolverMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SEACOR88888TermLoanMember" name="SEACOR88888TermLoanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SEACORAlpsMember" name="SEACORAlpsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_BNDESEquipmentConstructionFinanceNotesMember" name="BNDESEquipmentConstructionFinanceNotesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_LoanFacilityWithDNBBankASAMember" name="LoanFacilityWithDNBBankASAMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_LongtermDebtObligationGuranteeMember" name="LongtermDebtObligationGuranteeMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_LeaseObligationGuranteeMember" name="LeaseObligationGuranteeMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_LaborAndPerformanceGuaranteesMember" name="LaborAndPerformanceGuaranteesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_DebtInstrumentPercentageOfFinancingOnTotalPurchasePrice" name="DebtInstrumentPercentageOfFinancingOnTotalPurchasePrice" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" 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_NumberOfOperatingLeasesOnEquipment" name="NumberOfOperatingLeasesOnEquipment" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_SupplyVesselsCertainFacilitiesAndOtherEquipmentsMember" name="SupplyVesselsCertainFacilitiesAndOtherEquipmentsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_VesselsMember" name="VesselsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_OtherEquipmentMember" name="OtherEquipmentMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_EffectiveIncomeTaxRateReconciliationForeignIncomeTaxNotCreditablePercent" name="EffectiveIncomeTaxRateReconciliationForeignIncomeTaxNotCreditablePercent" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_EffectiveIncomeTaxRateReconciliationReturnToProvisionPercent" name="EffectiveIncomeTaxRateReconciliationReturnToProvisionPercent" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_DerivativesNotionalAmount" name="DerivativesNotionalAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="smhi_WindcatWorkboatsLtdMember" name="WindcatWorkboatsLtdMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_InterestRateSwapAgreementThreePointThreeTwoPercentMember" name="InterestRateSwapAgreementThreePointThreeTwoPercentMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SMFHMember" name="SMFHMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_InterestRateSwapAgreementThreePointOneNineFivePercentMember" name="InterestRateSwapAgreementThreePointOneNineFivePercentMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SEACOR88888Member" name="SEACOR88888Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_MexMarMember" name="MexMarMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_OSVPartnersMember" name="OSVPartnersMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_ConstructionReserveFundsFairValueDisclosure" name="ConstructionReserveFundsFairValueDisclosure" 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_ClassOfWarrantOrRightExercisedDuringPeriodExercisePrice" name="ClassOfWarrantOrRightExercisedDuringPeriodExercisePrice" type="num:perShareItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_CommonStockSharesWithheld" name="CommonStockSharesWithheld" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_WarrantsIssuedInPrivatePlacementMember" name="WarrantsIssuedInPrivatePlacementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_PIPEWarrantsMember" name="PIPEWarrantsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_ExchangeWarrantsMember" name="ExchangeWarrantsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_CarlyleGroupMember" name="CarlyleGroupMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_ConvertibleSeniorNotesConvertedToWarrantsMember" name="ConvertibleSeniorNotesConvertedToWarrantsMember" type="nonnum: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_SeabulkOverseasMember" name="SeabulkOverseasMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_FalconGlobalMember" name="FalconGlobalMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_OtherNoncontrollingInterestsMember" name="OtherNoncontrollingInterestsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_FalconGlobalHoldingMember" name="FalconGlobalHoldingMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_WindcatWorkboatsMember" name="WindcatWorkboatsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <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_PlatformSupplyVesselMember" name="PlatformSupplyVesselMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SEACORHoldingsMember" name="SEACORHoldingsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_FGUSACreditFacilityMember" name="FGUSACreditFacilityMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_TermLoanMember" name="TermLoanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_ProgramOfSocialIntegrationMember" name="ProgramOfSocialIntegrationMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_ContributionForFinancingOfSocialSecurityMember" name="ContributionForFinancingOfSocialSecurityMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_DebtAgreementMaximumBorrowingCapacity" name="DebtAgreementMaximumBorrowingCapacity" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_CostAllocationPercentage" name="CostAllocationPercentage" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="smhi_OperatingLeaseExpenseIncludingShortTermLeaseExpense" name="OperatingLeaseExpenseIncludingShortTermLeaseExpense" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <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_TimeCharterMember" name="TimeCharterMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_BareboatCharterMember" name="BareboatCharterMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_OtherMarineServicesMember" name="OtherMarineServicesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_PersonnelMember" name="PersonnelMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_RepairsAndMaintenanceMember" name="RepairsAndMaintenanceMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_DrydockingMember" name="DrydockingMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_InsuranceAndLossReservesMember" name="InsuranceAndLossReservesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_FuelLubesAndSuppliesMember" name="FuelLubesAndSuppliesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_OtherDirectCostsAndExpensesMember" name="OtherDirectCostsAndExpensesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <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_EquityInEarningsLossesOfOwnedCompanies" name="EquityInEarningsLossesOfOwnedCompanies" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_SegmentInformationLineItems" name="SegmentInformationLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="smhi_SegmentInformationTable" name="SegmentInformationTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" 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_DisposalGroupIncludingDiscontinuedOperationIncomeTaxExpenseBenefit" name="DisposalGroupIncludingDiscontinuedOperationIncomeTaxExpenseBenefit" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <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_OtherRevenueMember" name="OtherRevenueMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <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_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:element id="smhi_DisposalGroupNotDiscontinuedOperationAnticipateGainLossOnDisposal" name="DisposalGroupNotDiscontinuedOperationAnticipateGainLossOnDisposal" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_DisposalGroupNotDiscontinuedOperationReductionInLossOnDisposal" name="DisposalGroupNotDiscontinuedOperationReductionInLossOnDisposal" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="smhi_EmergencyResponseAndRescueVesselMember" name="EmergencyResponseAndRescueVesselMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
</xsd:schema>
