In 2002, Boston Whaler changed the naming of their boats and used 3 digits to identify the model instead of the older method of 2 digits.

Examples of new naming system starting in 2002;
2002 Sport 130
2002 Montauk 170
2002 Dauntless 180
2002 Ventura 210
2002 Outrage 260

NOTE: 2001 and older models did not use this naming system.
Look at the "original" decals on the side or console of your Whaler. That should give you a clue.
If it says Montauk 17', or 170 Montauk, that should be fairly explanatory?