The same name can be used by different shipowners and sometimes it makes some confusion when two ships with the same names are sailing in the same waters or staying in the same port.
From the legal part, this problem has been solved a long time ago and all ships are registered and have their unique IMO number, call sign, and MMSI or Maritime Mobile Service Identity number.
Why different prefixes are used?
Nowadays, anyone can find ship details and even ship particulars online and identify the purpose of the ship if needed. Back in the early days, it was common to use prefixes to ship names as abbreviations or full transcripts.
When the telegraph was the primary communication method, the length o the message was very important and could significantly save time and money. Imagine yourself a Captain and you need to inform your owners that “Motor Vessel Anna has Estimated Time of Arrival to Port of Calais 25th October 1200 Local Time”. Looks pretty long, but could be easily shortened to “MV Anna ETA Calais 25 October 1200LT”.
Now communication is performed by e-mails, but abbreviations are in use not only because of maritime traditions, but also to simplify communication.
For merchant fleet seafarers, the practical side of the prefixes was to identify ship propulsion as it could have a direct influence on the rules applied at sea regulated by COLREG. For example, “MV” or motor vessel gives the way to “SY” a sailing yacht, and “SV” a sailing vessel.
What differs between these ships?
Modern ships are most commonly called motorized, but there are only three prefixes used, “MV” for motor vessels, “MT” for motor tankers, and “MS” for motor ships.
The most noticeable prefixes are such as “SS” for a screw steamship and “PS” for a paddle steamer. Both are powered by steam engines and use propellers or paddle wheelers accordingly. Nuclear power is also used as a source for propulsion and this type of ship start with the prefix “NS” or nuclear ship.
However, in real life, the list of prefixes of modern ships continues with prefixes reflecting the purpose of the vessel and extends with new types of ships.
A special place should be given to FV or fishing vessels. This type of ship has its own place in COLREG and may be involved in operations and must be given way.
The vast majority of prefixes are used by passenger ships, gas carriers, and offshore vessels. Here is a full list of prefixes used in the merchant fleet.
|Ship Prefix||Ship Prefix Meaning|
|AHT||Anchor handling tug|
|AHTS||Anchor handling tug supply vessel|
|CS||Cable ship or Cable layer|
|DEPV||Diesel Electric Paddle Vessel|
|DCV||Deepwater Construction Vessel|
|ERRV||Emergency Response Rescue Vessel|
|RV / RSV||Research vessel/Research Survey Vessel|
|FT||Factory Stern Trawler|
|FPSO||Floating production storage and offloading vessel|
|LNG/C||Liquefied natural gas carrier|
|LPG/C||Liquefied petroleum gas carrier|
|HLV||Heavy lift vessel|
|MSV||Multipurpose support/supply vessel|
|MSY||Motor Sailing Yacht|
|MTS||Marine towage and salvage/tugboat|
|IRV||International Research Vessel|
|HTV||Heavy transport vessel|
|OSV||Offshore supply vessel|
|PSV||Platform supply vessel|
|SSCV||Semi-submersible crane vessel|
|STS||Sail training ship|
|ULCC||Ultra Large Crude Carrier|
|VLCC||Very Large Crude Carrier|
|ULBC||Ultra Large Bulk Carrier|
|ULCV||Ultra Large Container Vessel|
|TSHD||Trailing Suction Hopper Dredger|