A vessel's type can be deducted using the information contained in the AIS-transmitted messages that she is emitting. The vessel's crew or the accountable officer are responsible for correctly entering this piece of information to the vessel's AIS transponder.
AIS SHIPTYPE usually consists of two digits.
The first digit represents the general category of the subject vessel:
1 = Reserved
2 = Wing In Ground
3 = Special Category
4 = High-Speed Craft
5 = Special Category
6 = Passenger
7 = Cargo
8 = Tanker
9 = Other
In certain cases (e.g. Cargo Vessels, Tankers), the second digit provides additional information regarding the subject vessel's type of cargo, according to IMO.
1 = Category X
2 = Category Y
3 = Category Z
4 = Other Substances (OS)
The following table contains the relevant list:
| SHIPTYPE | TYPE NAME | AIS TYPE SUMMARY | DETAILED TYPE |
| 10-19 | Reserved | Unspecified | |
| 20-28 | Wing In Grnd | Wing in Grnd | Wing In Ground Effect Vessel |
| 29 | SAR Aircraft | Search and Rescue | |
| 30 | Fishing | Fishing | Fishing Vessel Trawler Fishery Protection/Research Fish Carrier Fish Factory Factory Trawler Fish Storage Barge Fishery Research Vessel Fishery Patrol Vessel Fishery Support Vessel |
| 31 | Tug | Tug | Towing Vessel Tug/Tender Tug/Supply Vessel Tug/Fire Fighting Vessel Tug Tug/Pilot Ship Anchor Handling Salvage Tug Towing/Pushing Tug/Ice Breaker Tractor Tug Tug/Support Articulated Pusher Tug |
| 32 | Tug | Tug | |
| 33 | Dredger | Special Craft | Suction Hopper Dredger Dredger Drill Ship Grab Hopper Dredger Grab Dredger Sand Suction Dredger Hopper Dredger Cutter Suction Dredger Cutter Suction Hopper Dredger Suction Dredger Bucket Dredger Trailing Suction Hopper Dredge Trailing Suction Dredger Inland Dredger Drilling Jack Up Bucket Ladder Dredger Drill Barge Bucket Hopper Dredger Bucket Dredger Pontoon Bucket Wheel Suction Dredger Dredging Pontoon Backhoe Dredger Suction Dredger Pontoon Water Jet Dredging Pontoon Grab Dredger Pontoon Kelp Dredger |
| 34 | Dive Vessel | Special Craft | Diving Support Vessel |
| 35 | Military Ops | Special Craft | Naval/Naval Auxiliary Vessel Naval Auxiliary Tug Logistics Naval Vessel Mine Hunter Minesweeper Combat Vessel Command Vessel Naval Salvage Vessel Torpedo Recovery Vessel Naval Research Vessel Naval Patrol Vessel Troopship Radar Vessel |
| 36 | Sailing Vessel | Sailing Vessel | Sailing Vessel |
| 37 | Pleasure Craft | Pleasure Craft | Yacht Museum Ship Exhibition Ship Floating Hotel/Restaurant Theatre Vessel |
| 38 | Reserved | Unspecified | |
| 39 | Reserved | Unspecified | |
| 40-49 | High-Speed Craft | High-Speed Craft | Hydrofoil Hovercraft |
| 50 | Pilot Vessel | Special Craft | |
| 51 | SAR | Search and Rescue | Salvage/Rescue Vessel Offshore Safety Vessel Standby Safety Vessel |
| 52 | Tug | Tug | Icebreaker Inland Tug Pusher Tug |
| 53 | Port Tender | Special Craft | Tender Crew Boat Pilot Ship Supply Tender |
| 54 | Anti-Pollution | Special Craft | Pollution Control Vessel |
| 55 | Law Enforce | Special Craft | Patrol Vessel |
| 56 | Local Vessel | Special Craft | |
| 57 | Local Vessel | Special Craft | |
| 58 | Medical Trans | Special Craft | Hospital Ship |
| 59 | Special Craft | Special Craft | Multi Purpose Offshore Vessel Barge Carrier Heavy Lift Vessel Special Vessel Maintenance Vessel Pipe Layer Waste Disposal Vessel Supply Vessel Training Ship Floating Storage/Production Radio Ship Research/Survey Vessel Repair Ship Support Vessel Fire Fighting Tractor Tug Landing Craft Floating Crane Fire Fighting/Supply Vessel Whaler Multi-Purpose Vessel Tank-Cleaning Vessel Mining Vessel Fire Fighting Vessel Paddle Ship Anchor Handling Vessel Nuclear Fuel Carrier Sludge Carrier Whale Factory Utility Vessel Work Vessel Platform Mission Ship Buoy-Laying Vessel Well Stimulation Vessel Motor Hopper Cable Layer Anchor Handling/Fire Fighting Crane Ship Inland Supply Vessel Offshore Supply Ship Trenching Support Vessel Offshore Construction Jack Up Pile Driving Vessel Replenishment Vessel Construction Support Vessel Pipelay Crane Vessel Crane Barge Work Pontoon Production Testing Vessel Floating Sheerleg Mooring Vessel Diving Support Platform Support Jack Up Sealer Trans Shipment Vessel Floating Linkspan Crane Jack Up Pumping Platform Air Cushion Vessel Power Station Vessel Supply Jack Up Radar Platform Jacket Launching Pontoon Pipe Layer Platform Pipe Burying Vessel Air Cushion Patrol Vessel Air Cushion Work Vessel Pearl Shells Carrier Steam Supply Pontoon Incinerator Jack Up Barge Desalination Pontoon Grain Elevating Pontoon |
| 60-69 | Passenger | Passenger | Passengers Ship Inland Passengers Ship Inland Ferry Floating Hotel Ferry Ro-Ro/Passenger Ship Accommodation Ship Accommodation Barge Accommodation Jack Up Accommodation Vessel Passengers Landing Craft Houseboat Accommodation Platform Air Cushion Passenger Ship Air Cushion Ro-Ro/Passenger Sh |
| 70 | Cargo | Cargo | Passenger/Cargo Ship Livestock Carrier Bulk Carrier Ore Carrier General Cargo Wood Chips Carrier Container Ship Ro-Ro Cargo Reefer Heavy Load Carrier Barge Ro-Ro/Container Carrier Inland Cargo Cement Carrier Reefer/Containership Vegetable/Animal Oil Tanker Obo Carrier Vehicles Carrier Inland Ro-Ro Cargo Ship Rail/Vehicles Carrier Pallet Carrier Cargo Barge Hopper Barge Deck Cargo Ship Cargo/Containership Aggregates Carrier Limestone Carrier Ore/Oil Carrier Self Discharging Bulk Carrier Deck Cargo Pontoon Bulk Carrier With Vehicle Deck Pipe Carrier Cement Barge Stone Carrier Bulk Storage Barge Aggregates Barge Timber Carrier Bulker Trans Shipment Barge Powder Carrier Cabu Carrier Vehicle Carrier Cargo |
| 71 | Cargo - Hazard X (Major) | Cargo | |
| 72 | Cargo - Hazard Y | Cargo | |
| 73 | Cargo - Hazard Z (Minor) | Cargo | |
| 74 | Cargo - Hazard OS (Recognizable) |
Cargo | |
| 75-79 | Cargo | Cargo | |
| 80 | Tanker | Tanker | Tanker Asphalt/Bitumen Tanker Chemical Tanker Crude Oil Tanker Inland Tanker Fruit Juice Tanker Bunkering Tanker Wine Tanker Oil Products Tanker Oil/Chemical Tanker Water Tanker Tank Barge Edible Oil Tanker Lpg/Chemical Tanker Shuttle Tanker Co2 Tanker |
| 81 | Tanker - Hazard A (Major) | Tanker | |
| 82 | Tanker - Hazard B | Tanker | |
| 83 | Tanker - Hazard C (Minor) | Tanker | |
| 84 | Tanker - Hazard D (Recognizable) | Tanker | Lng Tanker Lpg Tanker Gas Carrier |
| 85-89 | Tanker | Tanker | |
| 90-99 | Other | Other |
Note that, if you are using MarineTraffic API Services, it is possible to get SHIPTYPE responses such as those included in the next table (not AIS-derived):
| ID | SHIPTYPE |
| 100 | Navigation Aid |
| 101 | Reference Point |
| 102 | RACON |
| 103 | OffShore Structure |
| 104 | Spare |
| 105 | Light, without Sectors |
| 106 | Light, with Sectors |
| 107 | Leading Light Front |
| 108 | Leading Light Rear |
| 109 | Beacon, Cardinal N |
| 110 | Beacon, Cardinal E |
| 111 | Beacon, Cardinal S |
| 112 | Beacon, Cardinal W |
| 113 | Beacon, Port Hand |
| 114 | Beacon, Starboard Hand |
| 115 | Beacon, Preferred Channel Port hand |
| 116 | Beacon, Preferred Channel Starboard hand |
| 117 | Beacon, Isolated danger |
| 118 | Beacon, Safe Water |
| 119 | Beacon, Special Mark |
| 120 | Cardinal Mark N |
| 121 | Cardinal Mark E |
| 122 | Cardinal Mark S |
| 123 | Cardinal Mark W |
| 124 | Port Hand Mark |
| 125 | Starboard Hand Mark |
| 126 | Preferred Channel Port Hand |
| 127 | Preferred Channel Starboard Hand |
| 128 | Isolated Danger |
| 129 | Safe Water |
| 130 | Manned VTS |
| 131 | Light Vessel |