Glassing Single Fin

General Discussion
1

OK, Im on my 7th board(shape & glass), and I want to know if when I put my single fin onto the board which way would be the strongest and correct. I have searched the threads and came up with nothing. Should I glass it onto the board after I glass the bottom and then hot coat it all as one? Or should I glass it after sanding the hot coat? Should I use double 6oz on both sides all the way up or just rope and half way up? Which is stronger and the standard? This is my first longboard old style 9’2", 23, 3 1/8, 50/50 rails and 1inch redwood stringer, concave nose. Im also going to try a glass leash hoop, still havent figured that out yet. Anyway Ill post pics as I go. Thanks for the help, this is a great site. R

2

This is how I would do it but it may not be what’s currently done in production boards:

  • Glass the fin on just after laminating the bottom (when resin has set, of course).

  • Use decreasing lengths patches of cloth: one going up to the top of the fin, one half the height. (Or one full length, one 2/3 and one 1/3).

  • If I were you, I’d use UV resin (plenty of time to drive all bubbles out of the glass rope, and once everything is clean just let the sun -or UV lights- do the job. Same for the glass loop.)

  • Hot-coat the bottom, brushing the fin at the same time.

  • Sanding and glossing as usual.

Have fun.

3

Thanks for the input. I completely forgot about suncure! This will make it a cinch, now that I have the glass layout. I will post pics when finished. thanks. R

4

Balsa and Neptune. I use roving or glass rope along the base in addition to the glass cloth. Balsa, you’re a pro. Did you forget to mention this step or have you found no need for the rope around the base? Mike

5

Neptune: I put 'em on just after the lam.

Stand it up in position

use tape to hold it in place

mix a small thickened batch of resin, maybe a teaspoon or two, and use it to tack the fin in place

when the tack is set, remove the tape

Make some rope from scrap glass. If the base is 6 inches, then take apart a square of glass 9 inches on a side. you might want more.

Cut two layers of glass to go up the fin all the way, and onto the bottom a couple inches

lay the rope along either side of the base

Mix lam resin and wet the rope with brush and resin, push out bubbles to the ends

lay glass on and wet out with brush, one layer each side until done.

You’re done, clean brush.

Before you hot coat, you may want to brush a cheater coat of lam resin on if needed. don’t hesitate to use plenty resin, it will allow you to sand and fair the job later.

Actually, I almost never glass on fins. it’s a lot of hand sanding to get the fillet just right. It’s easier to use a router and set a long fin box.

6

Thnx, Charlie

I usually only use fin boxes myself but it seems everything these days is going to the machines. I want to try to do it the old school hand touched way. Im a finish carpenter by trade and so hand sanding doesnt bother me. I tried to take it a step further and shape and foil my own fin but that seemed to much work and to easy to mess up. Thnx for the input. R

7
Quote:

Balsa and Neptune. I use roving or glass rope along the base in addition to the glass cloth. Balsa, you’re a pro. Did you forget to mention this step or have you found no need for the rope around the base? Mike

This is what I wrote:

“(plenty of time to drive all bubbles out of the glass rope, and once everything is clean just let the sun -or UV lights- do the job. Same for the glass loop.)”

I didn’t forget the glass rope, I just assumed your question was about how many layers of fiberglass and how to set them.

Just like Honolulu, I do prefer installing a fin box. If I have to glass a fin on, I use cyanoacrylate glue to set the fin in place, then work.

Now, am I a “pro”? That is a good question… If Jim Phillips or Bill Thrailkill or Bill Barnfield or… are pros, what the hell am I?

I think we’re all still learning and making mistakes. And just trying to help newbies not to do the same.

Now, if you have children, you know that they usually don’t believe you untill they make their own mistakes… But let’s not get too philosophical. Let’s glass fins.

8

Guys,

In 1960 I abandoned the use of rope, or roving, when mounting a glass-on fin. The STRONGEST method, as described in part by Balsa, is to use staggared layers of glass cloth. I would use six, or even seven layers, on each side of the fin, using care to make the junction of the fin to bottom surface of the board, as tight as possible. The ‘‘secret’’ of exceptional strength, is to cut the cloth on a 45 degree bias. This puts twice the amount of fibers up the side of the fin, at that junction. In pre leash days, glass-on fins would routinely break on a trip to the beach. After adopting the above method, I NEVER had a fin crack, or break off. Today, with the leash in universal use, that level of strength may not be necessary, but it’s available if you want it. It’s not a method that lends itself well to a production environment, but great for one offs. It’s a method I still use to this day.

9

I used your method of glassing on a fin using the 45 degree cut in the cloth…

I dropped the board yesterday on its fin, almost sideways, its a three stringer 10’2", not only did the 12 inch tall fin hold but I didn’t even get stress cracks in the glass!

Thanks for all you contribute to us backyard guys!

10

Tony,

Thanks for the feedback. The usual case is that you never hear if your suggestions worked out well for someone. Given the accident you described, you must have done an excellent job of mounting the fin. Sounds like you put your fin to the maximum stress test! If you had any doubts, about the method, I expect those doubts are gone now. Thanks again, for taking the time.