Which actual FPB is it?.We need to know that to find the length. At 1/2" to the foot 34" gives 68 feet for example👍👍

Do a search and see if you can find the length oh the original boat was. Then I can show you the math.

Example:

90' boat / 45" model

45 divided by 90 equals .5 or 1/2"

So 1/2" = 1'-0" or 1/24th scale

You get scale ... 12" divided by 1/2" equals 24
Good luck, Joe