<P> These tables list both current and historical prefixes known to have been used . </P> <P> These prefixes are generally used for merchant vessels of any nationality . </P> <Table> <Tr> <Th> Prefix </Th> <Th> Meaning </Th> </Tr> <Tr> <Td> AE </Td> <Td> Ammunition ship </Td> </Tr> <Tr> <Td> AFS </Td> <Td> Combat stores ship </Td> </Tr> <Tr> <Td> AHT </Td> <Td> Anchor Handling Tug </Td> </Tr> <Tr> <Td> AHTS </Td> <Td> Anchor Handling Tug Supply vessel </Td> </Tr> <Tr> <Td> AO </Td> <Td> United States Navy oiler </Td> </Tr> <Tr> <Td> AOG </Td> <Td> Gasoline tanker </Td> </Tr> <Tr> <Td> AOR </Td> <Td> Auxiliary, Replenishment Oiler </Td> </Tr> <Tr> <Td> AOT </Td> <Td> Transport Oiler </Td> </Tr> <Tr> <Td> ATB </Td> <Td> Articulated Tug Barge </Td> </Tr> <Tr> <Td> CRV </Td> <Td> Coastal Research Vessel </Td> </Tr> <Tr> <Td> C / F </Td> <Td> Car Ferry </Td> </Tr> <Tr> <Td> CS </Td> <Td> Container Ship, Cable Ship </Td> </Tr> <Tr> <Td> DB </Td> <Td> Derrick Barge </Td> </Tr> <Tr> <Td> DEPV </Td> <Td> Diesel Electric Paddle Vessel </Td> </Tr> <Tr> <Td> DLB </Td> <Td> Derrick Lay Barge </Td> </Tr> <Tr> <Td> DCV </Td> <Td> Deepwater Construction Vessel </Td> </Tr> <Tr> <Td> DSV </Td> <Td> Diving Support Vessel / Deep Submergence Vehicle </Td> </Tr> <Tr> <Td> DV </Td> <Td> Dead vessel </Td> </Tr> <Tr> <Td> ERRV </Td> <Td> Emergency Response Rescue Vessel </Td> </Tr> <Tr> <Td> FPSO </Td> <Td> Floating Production, Storage and Offloading Vessel </Td> </Tr> <Tr> <Td> FPV </Td> <Td> Free Piston Vessel </Td> </Tr> <Tr> <Td> FPV </Td> <Td> Fishery Protection Vessel </Td> </Tr> <Tr> <Td> FT </Td> <Td> Factory Stern Trawler </Td> </Tr> <Tr> <Td> FV </Td> <Td> Fishing Vessel </Td> </Tr> <Tr> <Td> GTS </Td> <Td> Gas Turbine Ship </Td> </Tr> <Tr> <Td> HLV </Td> <Td> Heavy lift vessel </Td> </Tr> <Tr> <Td> HMT </Td> <Td> Hired Military Transport (not currently in use) </Td> </Tr> <Tr> <Td> HSC </Td> <Td> High Speed Craft </Td> </Tr> <Tr> <Td> HSF </Td> <Td> High Speed Ferry </Td> </Tr> <Tr> <Td> HTV </Td> <Td> Heavy Transport Vessel </Td> </Tr> <Tr> <Td> IRV </Td> <Td> International Research Vessel </Td> </Tr> <Tr> <Td> ITB </Td> <Td> Integrated Tug barge </Td> </Tr> <Tr> <Td> LB </Td> <Td> Liftboat </Td> </Tr> <Tr> <Td> LNG / C </Td> <Td> Liquefied natural gas carrier </Td> </Tr> <Tr> <Td> LPG / C </Td> <Td> Liquefied petroleum gas carrier </Td> </Tr> <Tr> <Td> MF </Td> <Td> Motor Ferry </Td> </Tr> <Tr> <Td> MFV </Td> <Td> Motor Fishing Vessel (mainly UK Royal Naval Reserve) </Td> </Tr> <Tr> <Td> MS (M / S) </Td> <Td> Motor Ship (interchangeable with MV) </Td> </Tr> <Tr> <Td> MSV </Td> <Td> Multipurpose support / supply vessel </Td> </Tr> <Tr> <Td> MSY </Td> <Td> Motor Sailing Yacht </Td> </Tr> <Tr> <Td> MT </Td> <Td> Motor Tanker </Td> </Tr> <Tr> <Td> MTS </Td> <Td> Marine Towage and Salvage / Tugboat </Td> </Tr> <Tr> <Td> MV (M / V) </Td> <Td> Motor Vessel (interchangeable with MS) </Td> </Tr> <Tr> <Td> MY </Td> <Td> Motor Yacht </Td> </Tr> <Tr> <Td> NB </Td> <Td> Narrowboat </Td> </Tr> <Tr> <Td> NRV </Td> <Td> NATO Research Vessel </Td> </Tr> <Tr> <Td> NS </Td> <Td> Nuclear Ship </Td> </Tr> <Tr> <Td> OSV </Td> <Td> Offshore supply vessel </Td> </Tr> <Tr> <Td> PS </Td> <Td> Paddle Steamer </Td> </Tr> <Tr> <Td> PSV </Td> <Td> Platform Supply Vessel </Td> </Tr> <Tr> <Td> QSMV </Td> <Td> Quadruple Screw Motor Vessel </Td> </Tr> <Tr> <Td> QTEV </Td> <Td> Quadruple Turbo Electric Vessel </Td> </Tr> <Tr> <Td> RMS </Td> <Td> Royal Mail Ship or Royal Mail Steamer </Td> </Tr> <Tr> <Td> RNLB </Td> <Td> Royal National Lifeboat </Td> </Tr> <Tr> <Td> RRS </Td> <Td> Royal Research Ship </Td> </Tr> <Tr> <Td> RV / RSV </Td> <Td> Research Vessel </Td> </Tr> <Tr> <Td> SB </Td> <Td> Sailing Barge </Td> </Tr> <Tr> <Td> SS (S / S) </Td> <Td> Single - screw Steamship (also usage as generic term for any steamship) </Td> </Tr> <Tr> <Td> SSCV </Td> <Td> Semi-Submersible Crane Vessel </Td> </Tr> <Tr> <Td> SSS </Td> <Td> Sea Scout Ship </Td> </Tr> <Tr> <Td> SSV </Td> <Td> Sailing School Vessel, Submarine and Special Warfare Support Vessel </Td> </Tr> <Tr> <Td> ST </Td> <Td> Steam Tug or Steam Trawler </Td> </Tr> <Tr> <Td> STS </Td> <Td> Sail Training Ship </Td> </Tr> <Tr> <Td> STV </Td> <Td> Sail Training Vessel or Steam Turbine Vessel </Td> </Tr> <Tr> <Td> SV (S / V) </Td> <Td> Sailing Vessel </Td> </Tr> <Tr> <Td> SY </Td> <Td> Sailing Yacht or Steam Yacht </Td> </Tr> <Tr> <Td> TB </Td> <Td> Tug boat </Td> </Tr> <Tr> <Td> TEV </Td> <Td> Turbine Electric Vessel </Td> </Tr> <Tr> <Td> TIV </Td> <Td> Turbine Installation Vessel </Td> </Tr> <Tr> <Td> TrSS </Td> <Td> Triple - Screw Steamship or steamer </Td> </Tr> <Tr> <Td> TS </Td> <Td> Training Ship or Turbine Steamship or Turbine steam ship </Td> </Tr> <Tr> <Td> Tr. SMV </Td> <Td> Triple - Screw Motor Vessel </Td> </Tr> <Tr> <Td> TSMV </Td> <Td> Twin - Screw Motor Vessel </Td> </Tr> <Tr> <Td> TSS </Td> <Td> Twin - Screw Steamship or steamer </Td> </Tr> <Tr> <Td> TST </Td> <Td> Twin - Screw Tug </Td> </Tr> <Tr> <Td> TV </Td> <Td> Training vessel </Td> </Tr> <Tr> <Td> VSS </Td> <Td> Virgin SpaceShip, (space - going experimental air planes by Virgin Galactic) </Td> </Tr> <Tr> <Td> YD </Td> <Td> Yard Derrick </Td> </Tr> <Tr> <Td> YW </Td> <Td> Water Barge, self - propelled </Td> </Tr> <Tr> <Td> YOS </Td> <Td> Concrete vessel </Td> </Tr> </Table> <Tr> <Th> Prefix </Th> <Th> Meaning </Th> </Tr>

What does s s stand for on a boat