<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>4/A</documentType><periodOfReport>2003-08-01</periodOfReport><dateOfOriginalSubmission>2003-08-22</dateOfOriginalSubmission>
    <issuer>
        <issuerCik>0001169237</issuerCik>
        <issuerName>BIW LTD</issuerName>
        <issuerTradingSymbol>BIW</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001192113</rptOwnerCik>
            <rptOwnerName>ADANTI MICHAEL J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O BIW LIMITED</rptOwnerStreet1>
            <rptOwnerStreet2>230 BEAVER STREET</rptOwnerStreet2>
            <rptOwnerCity>ANSONIA</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06401</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>1</isDirector><isOfficer>0</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther></reportingOwnerRelationship></reportingOwner><derivativeTable><derivativeTransaction><securityTitle><value>Stock Option (Right to Buy)</value></securityTitle><conversionOrExercisePrice><value>18.08</value></conversionOrExercisePrice><transactionDate><value>2003-08-01</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>2500</value></transactionShares><transactionPricePerShare><footnoteId id="F3"/></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><footnoteId id="F1"/></exerciseDate><expirationDate><value>2013-07-31</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common</value></underlyingSecurityTitle><underlyingSecurityShares><value>2500</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>2500</value><footnoteId id="F2"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeTransaction></derivativeTable><footnotes><footnote id="F1">1,250 are exercisable on 08/01/2004 and 1,250 are exercisable on 08/01/2005.</footnote><footnote id="F2">Amended to report correct number</footnote><footnote id="F3">Option grant which does not have purchase price.</footnote></footnotes><remarks>This Form 4 is amended to correct, among other things, the date of the transaction required to be reported.</remarks><ownerSignature><signatureName>Henrietta Vitale pursuant to power of attorney previously submitted</signatureName><signatureDate>2003-09-04</signatureDate></ownerSignature></ownershipDocument>

