How to Identify your Boat Hull ID Number

How to identify your Boat Hull ID numberAt some point, you may have wondered what that long group of letters and numbers are on the transom of your boat. After reading this article, you should be able to correctly identify where your HIN(Hull Identification Number) is located, determine your boat manufacturer, your boat hull serial number, and your boat certification date.

The Federal government requires that every boat has a HIN number displayed no less then ¼ inch high on the starboard side of the transom. The HIN must be engraved or permanently attached within two inches of the transom top. On boats such as catamarans and pontoons, the HIN or CIN must be printed on the crossbeam.

According to, “From June 1998, the European Recreational Craft Directive required that every new boat sold or put into service in the EU to have a HIN displayed conforming to the Directive.“ Also according to, “From 1 January 2006 the European Recreational Directive was amended and the HIN renamed CIN (Craft Identification Number) for the EU market.”

Boats manufactured in Europe will have a country code in front of the CIN. An example for the country Italy would be IT-4WN12365E587.

Boats that are manufactured or imported on or after November 1, 1972 were required by federal law to have an HIN (Hull Identification Number). The HIN enables manufacturers to uniquely identify each boat.

The HIN is broken down like this:

 4WN 00005 0872

 4WN = Manufacturer ID Code

00005 = Hull Serial Number

0872 = Date of Certification ( 08 = August, 72 = 1972 )

 Some may look like this:

 4WN 00005 N75D

 The last part of this HIN changes and becomes alphanumeric. The N75D also identifies the date range. You may view the list for the month codes below:

 A - August

B – September

C - October

D - November

E - December

F - January

G - February

H - March

I – April

J – May

K – June

L – July

The HIN format changed after August 1, 1984 and has since stayed the same. The HIN now appears in this format:

 4WN 00005 E5 87

 4WN = Manufacturer ID Code

00005 = Hull serial number

E5 = Date of certification or manufacturer ( May 5 )

87 = Model year

 A – January

B – February

C - March

D - April

E – May

F – June

G - July

H - August

I - September

J - October

K - November

L - December

The Boating Safety Resource Center compiled a list of all registered boat manufacturers and created a tool to identify the three character code assigned to them. You may view them here:

Unfortunately, there are currently no resources available to determine what the serial number stands for in the HIN or CIN. The boat manufacturer most likely has a certain pattern that all their Identification numbers will match. Boaters may be able to contact the manufacturer for further information regarding their serial number.

Now that you’ve read through the instructions, take a step outside to your boat and write the HID number down and try it for yourself!



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3 Responses to How to Identify your Boat Hull ID Number

  1. Melissa Siebenaller says:

    i figured out the HIN number and now i have no idea how to identify the kind of boat it is. my father was killed in an auto accident recently and this was left for me but we cant find the title…we were told its a 1957 criss craft but i have NO clue how to find out if indeed they r correct…PLEASE HELP

  2. LaRae Murphy says:

    We have a 15’6 Cobra and this is the only number I can find 6F031-6. ANy idea on how to search for it?

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