First, I would suggest "filling in" the area that has the chip.
Marine Tex would be a good "filled epoxy" to use for this.
It comes in white/black and grey colors.
Clean the area inside the chip.... maybe take a file and give it
a bie of a radius.
Mix up a small amount of Marine Tex (it's a 2 part filled epoxy).
Use masking tape to mold the Marine Tex to the profile of the fin head.
When the Marine Tex has cured take a file and smooth the repaired area
flush with the surrounding profile of the fin head.
OK, Tuttle fins need to fit snugly on the sides.
The sides should be a uniform size to pretty close tolerance.
The sides of the Tuttle fin head should be a push fit all the way down (mostly
they never fit this well, but ideally it's a zero clearance fit between the fin head
and the sides of the fin box.
What regulates the height that the fin head goes into the fin box is the front and
If you are seeing slow progress with the soap and the file, where is the fin head hitting
(i.e. where are the "shiny spots" on the front and rear tapers) it might be worthwhile to take
a flashlight and look down into the fin box in the board and ensure that there are no "lumps"
of epoxy. Sometimes the fin fitters at the factory will take a lump of black epoxy filler and
stick it on the back taper in the fin box to get a fin the goes too far in to seat at the correct
If there are any lumps, take a small round (rat tail) file and blend the lump into the rest of the
When fitting and filing with soap as a marking media, be sure that you only file off the shiny
spots where there has been hard contact between the fin head and the fin box.
Yes, ideally the fin root will be a push fit down the sides of the fin box until the fin root/head
stands proud (above) of the bottom surface of your board by about 1/32" (0.8 mm).
The last 1/32" is the "draw" on the tapers that will ensure your fin really stays in your board.
The screws are used to draw the fin that last 1/32" and then they fin screws simply ensure
that the fin stays "stuck" in your board at that level.
The fin screws do not provide any support for the fin...... the side fit and the draw into
the front and rear tapers provide positive location of the fin.
If you are getting some spin out, ensure that there are not paint lines or stickers on the
foil of the fin. Often it's necessary to take some 400-600 grit wet/dry abrasive cloth (sand paper)
and smooth/blend any tiny ridges into the rest of the foil.
Hope this helps,