What is the significance of the AIS Shiptype number?

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

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