International Association of Marine Investigators, Inc.   C CLAIMS
International Association of Marine Investigators, Inc.















Serial numbers of all kinds are vital to Dealers and Insurers as they provide the only definitive way to individually identify marine property. Many times serial numbers are incorrectly quoted and this can lead to subsequent confusion both for dealers and Insurers


Hull identification serial numbers (HIN’s) should on all vessels built after June 1998 appear in the international ISO format with fourteen characters. The prefix should be the country code followed by the MIC (Manufacturers code) – three letters. This is followed by the production model and serial number followed by the month of production and year of production or model year.

This is set out as follows in this example:

GB –MPP1A01234F001

GB (country code) – MPP (Manufacturers Code), 1A (Model)1234 (serial no.) F (month of build), 001 (year of manufacture or model year).

This ‘HIN’ should always appear on the transom permanently moulded or etched into the hull and occasionally on a permanently affixed plate. This is in the majority of cases to the starboard side of the transom.

Older hull identification serial numbers often have less characters and are presented in different formats. For example, Fairline Boats used a five or six character number or ‘yard’ number. Other larger manufacturers each had their own system and it is difficult to summarise every number configuration used.

Some speedboat manufacturers used a combination of model, serial number and year in their serial numbers (for example Fletcher used a simple model/serial number/year format on many models). This was presented on a plate on the dashboard.

Personal Water Craft 

All personal Water Craft utilise the standardised Hull identification numbering format used by US boat manufacturers and which is almost identical to the ISO standard. The ‘HIN’ is found on the aft section of every PWC on a plate and the inboard engines also carry a serial number stamped into the engine block or marked on a plate. In addition many PWC’s are fitted with ‘Datatag’ which carries the principle identification data. This information is also held by Datatag in their database (contact Datatag on tel: 01932 358000).

Outboard engines

There have been many outboard manufacturers over the years most of whom still survive though other older names such as Archimedes, Crescent, Chrysler (now Force) Seagull, Terhi etc have disappeared. In our Threestokes guide  you will find contact details for most of the importers and you can verify serial numbers through them. Older engine information is still in our Threestokes Guide  database and is available on application.

 In almost every case the serial number plate will be affixed to the engine swivel bracket either on a riveted plate or sticker and is obviously marked with the model and serial number code.

Here is a brief summary on some outboards:

  • Chrysler outboards – Model number of two to four characters followed by five or six digit serial number. The same system was used by Force (the successor to Chrysler).

Example: 709HA - 1234

  • Evinrude – These engines use a model code followed by a serial number. The usual format includes a four or five character model code (e.g. 4386C) followed by a serial number prefixed by the letter C or B and then six digits More recent Evinrudes have adopted a slightly different system. Example: E15BALCIS – B123456

  • Johnson  - These outboards were produced by the same group as Evinrude (OMC). The serial and model number format though similar, generally prefixed the serial number with a single letter prefix, followed by a five or six digit serial number. Example: BJ90TLECS – R12345678

  • Honda – These engines usually prefix with a four character model code (e.g. BBBL) followed by a six or seven digit serial number. Example: BBBL -1234567

  • Mariner – These engines were originally a mix of Mercury and Yamaha serial numbering systems though more recent engines follow the Mercury system. Some Yamaha origin engines prefix with a Yamaha style three or four character model code followed by a six digit serial number. Mercury based engines always use a typical Mercury system prefixing the serial number with OB then six digits.

  • Mercury – These engines always use a six digit serial number prefixed by OB or OC etc, Example: OB123456

  • Suzuki – These engines usually prefix with a two to six character model code (e.g.DT60) followed by a seven digit serial number. Example: DT40 RL - 0034567

  • Tohatsu – These engines usually have a two or three character model code (e.g. 4MS) followed by a five digit serial number. Example: 4MS - 12345

  • Yamaha – These engines usually have a model code prefix of up to seven letters/numbers (e.g. 80AETL) followed by a six digit serial number. Example: 80AETL - 123456


With nearly all inboard engines there are at least two numbers of importance. These are the engine serial number and the gearbox serial number. In outdrive installations you also need to concern yourself with the outdrive serial number and the transom shield number.

Serial numbers are always marked on inboard engines either on a riveted plate somewhere on the block and sometimes by being stamped into the engine block. These numbers often appear also on stickers placed on the head or intake housing so that they are conveniently accessible.

Here are some examples:

  • Caterpillar – These engines usually have a eight character serial number prefixed  with a model code. Serial number example: 13K123445

  • Cummins  - These engines usually have a simple eight digit serial number system – Example: 12345678

  • Mercruiser – These engines utilise a standardised two character prefix to all their component numbers. There are always six digits after the prefix.

Example: OM123456

  • OMC - These engine installations usually use a seven digit serial number often prefixed by the letter ‘T’. Similarly the transom shield and outdrives have a similar system in place. Example: T1018006

  • Perkins - These engines use a model prefix (e.g. 236T) followed usually by a seven or eight digit serial number. Example: 236T U 1234567

  • Volvo Penta – These engines use a lengthy serial number system usually starting 220 or similar with up to eleven digits in all. The model code usually appears as a combination of letters and digits e.g. AQ200D or KAD32 etc.

      Serial number example: 220 4130560



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