View Full Version : Larger Fin for my F155
14th March 2007, 02:52 AM
<dr nick voice> Hi Everybody! </nick voice>
got a question about fins for my older f155 It has a tuttle box in it, and I would really like to get a bigger fin to match my 10.5 sail.
Currently I have the stock 58 cm fin and a 55 cm fin with a wider chord.
I like the 58 cm fin with my 7.5... using that ratio, I would like to try a 65 - 70 cm fin with my 10.5
however, most fins that large do not have the tuttle box, they are deep tuttle.
so, as I see it, I can.
a) Look forever till I find that 70cm reg tutle box fin.
b) Replace the fin box with a DTT box
c) buy a DTT fin and make it a reg tutle fin by cutting the root down and drilling new screw holes. (yikes)
D) Figure out a way to make the DTT fin fit in the TT box. It looks like there is extra room in the box currently - the cavity height is larger than the height of a TT fin root. (double yikes)
what do you all have to say?
Anyone here run with a 70cm tutle fin? am I going to blow out the box? How about converting a fin?
14th March 2007, 04:49 AM
You may have one of the few F-155's in the USA with a std. Tuttle box.
Have you measured the depth of the fin box to ensure that you don'r really have a deep Tuttle box in your board?
Just becasue your board came supplied with a std. Tuttle root on the fin, does not mean that it's a std. Tuttle box.
So, measure the front and rear of the box and send me the numbers.
We can very quickly determine which box you have.
Yes, there's a good possibility of you "blowing out" the fin box with a 65-70 cm fin in a std. depth Tuttle box.
And, you probably won't find a fin that big with a std. Tuttle root.
So, you could modify a 65-70 cm fin to fit your std. Tuttle box (if for sure that's what you have) and plan on replacing the fin box (after you bolow it out) with a deep Tuttle fin box.
Let me know the depths of your fin box (from the bottom of the board) at the front and at the back. That will tell us which fin box you have.
Hope this helps,
15th March 2007, 08:45 PM
Will I need a 58 cm fin with a similar volume board and 9.6?
16th March 2007, 03:03 AM
That depends to the greatest extent on how wide youir board is.
A board with a narrower tail width (and less footstrap offset) will not benefit from a really long span fin in the same way as a board with a really wide tail width.
Plus, at some point, without the requisite footstrap offset, you won't be able to control the attitude of the fin very well.
It's a balance thing between the rig size, fin size, footstrap offset, and tail width.
To simply say that if you get a 9.6 m2 rig, you need a ?? cm fin doesn't nearly take into consideration all the factors here.
Board volume, tail width, footstrap offset, and volume distribution are the board factors.
Rig type (race, free race, or recreational can be another factor.
And, the conditions you intend to sail it all in.
Hopes this helps,
19th March 2007, 03:20 AM
The board is the 2000 formula model and came with a stock 58 cm reg tuttle fin. I took a tape to the inside of the box, and it sure seems like there is a lot of space in there...
Using a standard measuring tape, I could insert the tape 4 inches into the board at both the front and back ends. Looking inside the box however, it looks like the "wall" at the back of the box starts out tapering in for about 1.5 - 2 inches, and then shoots straight up to the top of the board.
I've always assumed that the box was a reg tuttle box based on this link
However I did think that there seemed like a lot of extra room in there. It does not appear as though any reworking or replacement has been done ( I am the second owner)
Are you saying that this board does have a dtt box? That would be GREAT!
I also have a 2001 start , the archive link just says tuttle box, would this board also have a DTT box?
Thanks so much
19th March 2007, 09:45 AM
Everything you are telling me supports the idea that your F-155 does indeed have a Deep Tuttle (DTT) fin box.
If the back of the fin box measures about 2" and then the box straightens out, and goes up to the top of the box, then you almost for sure have a DTT box.
The rear dimension on a DTT bos is 2.038" measured on the 10 deg. rear taper angle.
The front dimension (on the 10 deg. front taper angle) should be 2.698".
If the front taper also blends into a vertical cavity, then a DTT fin should fit in nicely with a lttile fitting.
If you have a std. Tuttle finb box, the front taper would be only about 2.00" deep (measured perpendicular to the bottom of the board) and 1.25 " deep at the rear (perpendicular to the bottom also).
If you know anyone who has a deep Tuttle fin, just try it in your fin box.
If it goes in to a solid stop with the root still sticking up about 0.700" (18,00 mm) then you have a std. Tuttle box.
If the test fin goes in nearly all the way, you definitely have a DTT box and you can buy any DTT fin and make it fit.
Hope this helps,
19th March 2007, 10:14 AM
I had the 2000 F155. Nice board. I'm sure I used to run a 62cm deep tuttle fin in it as well as the stock Curtis 58cm fin.
I've also had a few 2001 Starts as well, and it is a deep tuttle. I used to run a 65cm deep tuttle fin in it all the time.
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