If the 480 mm fin will not fit, what is the exact problem?
If the head of the fin is too thick and it's too tight on the sides,
then a few strokes with a smooth file should flatten it out
and bumps/ripples and then it should fit in nicely.
Take a bar of soap (the soap yoiu use to take a bath or shower)
and rub the soap on the root (the part that sticks into the board) of
your new fin.
This will act as a marking media to identify where the fin is too tight.
The soap will be grey in and milky looking when you rub it on.
When you insert the fin into the fin box, the "high spots" will turn shiny
and black. File off the shiny black spots only!
When you file your fin, be sure to cover the entire flat surface on the
side of the fin root.
File off any high spots.
Also take a flashlight and check down in the fin box cavity in your board.
Look for any lumps or ripples there as well. Very carefully file the sides of the fin box in the board but only if there are obvious places that would be tight when you insert the fin.
If your fin goes in most of the way, but you see shiny spots in the soap you rubbed on the fin root, these will be the places you need to file down slightly.
The front and rear tapers on a Tuttle fin are what control the depth of the fin into the fin box.
Also check the front and rear tapers in the fin box to see if there are any "lumps" of added
Take a round (rat tail) file and carefully work the lumps down a little at a time (keep trying the fin in the box to ensure you don't over do things) until the flat surface of the fin root is slightly higher than the surface of the bottom of your board.This last little bit is the "draw" and when you tighten up your fin screws the draw will ensure you have a nice snug fit between the fin and the fin box.
The "draw" needs to be approximately 1/64-1/32" (.04 mm-.08 mm)
Unfortunately, many boards need to have the fin "fitted" initially as the tolerances are very close.
It's better that it's a little too tight. Having it be too loose would mean you have to add some material to the outside of the fin root.
Hope this helps,
P.S. You can fit the fin using sand paper, but a file is the preferred tool as you can control where any material is removed far better, and the file removes more material
Last edited by Roger; 7th August 2008 at 09:25 PM.