RE: Hatteras and Fins
Abrasive paper works to fit a fin, but it takes forever, and does not allow you to take off only the high spots.
What you need is a bar of bathtub soap, and a file (perhaps 2 files one flat/half round double cut, and a double cut round (rat tail) file.
Rub the soap on the root of the fin. The soap will look dull and whitish.
Put the fin into the fin box and work it back and forth slightly.
Pull the fin back out and look at the root.
The dark shiny spots on the fin root are where the front and rear tapers are in hard contact with the tapers in the fin box.
Take your flat/half round file and just file off the shiny spots.
If the fin seems to be too thick, and you see shiny spots on the sides of the fin, rub those off carefully as well. Don't want to take anything extra off the sides as this is what supports your fin. The front and rear tapers control how far the fin goes into the fin box.
A correctly fitted fin should be snig most of the way in (Tuttle and Deep Tuttle) and should fit tight and flush (Powerbox and Power Taper Box (BIC).
Reapply the soap and fit the fin again.
When the fin is about 1/64" from full seated, and you have a nearly full contact pattern on the front and rear tapers, you are done.
That last 1/64" is the "draw" on the tapers that will keep your fin solid in the finbox.
If you find, as you are fitting the fin, that there's a big hard spot on the front or rear taper in the fin box, you might want to take the rat tail file and work that down a little. This may drop your other fins into the box a little further, so if all your other fins fit, skip the rat tail in the fin box procedure.
The file allows you to remove only the spots that are actually in contact, and allows you to progressively increase the contact area on the front and rear tapers.
If the overhang on the front of your new weed fin doesn't contact the board, you need to add a gasket to fill the sapce or build up the underside of the overhang until it's a good seal on the board.
Cut some fin sheath material and use a good contact cement to glue the foam fin sheath material to the overhang on the fin.
Here's another little trick to make the gasket fit and seal perfectly.
Cut a soda or beer can apart and use a flat section of the thin sheet metal of the can against your board.
Install the fin and tighten up the screw (s) so the glued on foam gasket and the sheet metal are clamped tightly to the bottom of your board.
Then take an exacto or razor knife and trim away the excess gasket.
You won't hurt the board as there's a tin "shield" protecting the bottom of your board.
When you are done, remove the fin and pull out the sheet metal.
Now your fin overhang will have a perfectly shaped and faired in gasket that fits the configuration of your board perfectly.
Hope this helps,