View Full Version : Deboichet Fin not fitting in my Isonic

25th June 2010, 01:18 AM
just bought an Isonic 144 WC and also ordered my deboichet R16 fin. The fin however doesn't fit into the board. It doesn't go half in, tried to use soap but didn't work. Do not want to force it in. What shall I do?

25th June 2010, 01:55 AM
Using sandpaper.

25th June 2010, 02:54 AM
You need to sand it to fit. Basic stuff.

25th June 2010, 03:26 AM
THanks for the replies. Any recommendation with regards to what sandpaper to use? ANd I assume I have to sand the fin not the board...... (sorry, never had this kind of problem before).

25th June 2010, 03:59 AM
Yes, you have to sand the fin and try to fit after a few wipes (equal amount) on each side. Till it goes in with resistance. Don't make it to small!!

mark h
25th June 2010, 04:31 AM
Normally a tiny bit of sanding on the leaing and tailing edge is enough to get a nice fit:)

25th June 2010, 07:33 AM
Hi Andy,
A file is a much better tool to use than "sandpaper".
A file will remove more material, faster, from where you NEED to remove
material than will any sort of abrasive cloth.
First, get a flashight and take a look in the interior of the fin box in your new board.
Check for "lumps" and bumps of black fill material sometimes used to make a stock fin
fit at the correct height.
Take a small round (rat tail) file and work out the lumps if they seem to be what's keeping your fin from fitting correctly.
Try to stay away from the sides (usualy the side fit is pretty good, but not always) unless you see major lumps on the sides as well.
Try to minimize the amout of filing you do down in the fin box.
Get a bar of soap (sounds like you already have one) and rub a layer of soap all over the head of your fin (both the sides and the front/rear tapered radii).
Push the fin down in the slot in your new board as far as it will go. Do not push it in too hard.
Pull the fin back out and see where the soap (dull and whitish when you rubbed it on the fin head) is shiny.
The shiny spots are what you need to file off.
Check if the sides of the fin head are shiny only part way down.
Use the file to carefully thin the side to side thickness by filing off the shiny spots.
Hit it with < 5 strokes of the file on each side. Try to keep things symmetrical by filing
the same number of strokes on each side.
If you see shiny (or perhaps black) spots on the front and rear tapered radii of the fin
file these a few strokes. Often the angle will be off slightly so you need to "correct" the
angle by filing the areas that are actually in contact, and not the adjacent areas that are not
in contact (the main issue I have with using sandpaper).
Work the "high spots" off a little at a time and your fin will soon fit right down in the slot.
Try to "fit your fin" so that the sides are a snug push fit and the front and rear tapers hold the fin around 1/32" proud (higher than) the bottom surface of your board.
You need a slight bit of "draw" on the fin to ensure that it's good and tight and that the
fin bolts do not do anything but keep your fin from falling out.
If you fit it correctly, you will have to "knock it" with your hand or a small rubber mallet to
get the tapers to "let go" to take the fin out after you have pulled the fin fully into the fin box with the fin screws.
The screws simply prevent the fin from falling out.
The side fit and the tapers actually hold the fin.
Hope this helps,

26th June 2010, 08:09 PM
Hi, thanks for all the advice.

Have now been sanding/filing the fin and now it at least fits into the board, with just some 1-2mm looking out as Roger said. However, after fixating the bolts the rear end keeps standing some 1-2mm out of the board's surface. The fin is sitting tight in the box and Im afraid that if I sand it more it will start getting loose.

Will see if I can get someone else to have a look and help me out.

Im not exactly new to the sport (have been surfing for 16 years), but this must be one of the most frustrating moments I've had. Spent a small fortune on fin and board and it takes such a huge effort to make it work (and you might still mess it up if you have filed it more in one side than the other). I thought these finboxes are standard sizes??? :(

26th June 2010, 08:52 PM
Hi Andy,
I feel your frustration.
It's happened to me several times, and always with the top of the line race/slalom boards, and not only with Starboard.
Also the high end fin manufacturers always seem to mold the fin heads slightly large so fitting is required. I asked Dennis Parton (Tectonics) about this once, and his comment was that it was better to have some material for fitting than to have the fin drop too far into the board and make the user "ADD" material for the fin to fit correctly.
This is a Deep Tuttle fin box... or Std Tuttle?
Get a good scale and measure the depth of the fin box and the height of the fin head to make sure the fin box is for sure deep enough.
I've seen a number of Deep Tuttle fin boxes or fin heads that were simply too shallow (box in the board) or too tall (fin head) and material needed to be taked off the top of the fin head for the fin to fit all the way into the board.
Do not worry about filing a little too much!
The correct way to fit a Deep Tuttle is to get the sides to fit nice and snug first.
Then file a little chamfer or radius along both sides of the top of the fin head so it starts into the box nicely,
Then get the end radius angles so you have full contact along the entire angle.
If you have to err here, try to get the bottom area of the radius (the area nearest the bottom of board) to fit correctly as this will give you the best support. Having the front and rear radius not touching way up inside the board is not so critical.
Use many iterations of soaping, then slightly filing the the front and rear tapers, as these are what set the height of the fin in the box.
The sides are what supports your fin when you are sailing, the front and rear tapers set how far the fin goes into the box.
Sounds like you are very close, a few more strokes with the file and it wil fit perfectly,
Do not forget to put a radius on the upper corners of the fin head.
This allows the fin to pivot out if you hit something, without damaging the fin box.
Hope this helps,

26th June 2010, 10:10 PM
Hello Roger

Is it possible to add some pictures?

27th June 2010, 02:59 AM
Hi Roger,
thanks a lot for taking the time to help me out. I've worked a bit more on filing/sanding and I'm very close to reaching 100% fit.
The frustration came because today was a sunny and windy day but I wasn't surfing since I was sitting at the beach sanding, soaping, filing, soaping, filing, etc. for quite some time.. :)
The fin is a deep tuttle R16 (finhead has some 70mm) and the finbox in the board is even slightly deeper than that.
But one thing that happened to me is that one of those white rings that is glued to the top of the board where the bolts go in got loose after the first time I fixed the bolts. What shall I use to glue it back?

27th June 2010, 06:15 AM
90% of the time I buy a new fin I have to sand the base of the fin. But I can tell you that it does not take days or hours to do it. Maybe 10 minutes per fin.
I sand the sides then the front and then the back and fit, move the fin around to mark where it is too tight and back to the sanding.
No more than 10 minutes.
I think the quality of the deboichet you have is by far the worse. Or you are doing something wrong here.

27th June 2010, 08:45 AM
Hi Andy,
If the fin does not sit flush in the box, you can certainly sail the board.
You will lose a tiny bit of top end speed (due to a little bit more drag at the
fin base, but the board will sail just fine.
Go sailing tomorrow!
As far as the white ring, use some contact cement to stick it back on.
If you know anyone who recently installed footpads on a board, the special
deck pad glue would be even better, but you only need a dab of it, not a whole
You dealer or a local board repair shop should have a used tube of the footpad glue.
Get some "SS fender washers" to use on top of the white rubber seals and they won't
deform and twist off.
Hope this helps,