I have done glassons on my last 3 boards and they look like crap. I cant make the fin rope stay to the fin and there are voids in between the fin and the rope. Could someone tell me how to put them on and make them look good. The archive has not helped me at all.



The glass rope is just to get that cool built up look around the fin base, you really get the strength from the glass cloth laminating on to the deck bottom and up the fin. Here’s what I do.

  1. Tack fin into place with hot glue or laminating resin

  2. Cut and laminate both sides of the fin with a smaller fin shaped glass patch. Onto the board and up the fin.

  3. Lay down about 4-6 pieces of saturated glass rope in each of the fin cracks, Filet out the glass rope on the leading edge and trailing edge. Make sure the rope is completely saturated in a cup and excess resin & air bubbles are pulled out by running the rope between your two fingers

  4. Cover the whole mess with another patch of glass. This time the glass patch is a little bigger than the last patch so it covers all the strings and what not.

  5. Do the glass rope and cloth patch again if you want it really bullet proof

  6. If there are any air bubbles get a small stiff 1/4 brush and work out the bubbles. Work only tip to tail, if you run tip to base you will cause more air bubbles when you pull the cloth out of the fin / deck crotch

  7. Hot coat, sand it flush to the deck, and slightly refoil the fin

Thats how i do it.


What do you mean by fin cracks?


is what was meant by fin cracks - the inside corners where the fin meets the bottom …and is also a pretty good illustration of the technique I use for pushing the wetted out glass rope fibers in there with a fingertip. Gets 'em in there pretty good and also starts the fillet joint nicely.

Deadly Flying Glove…or at least one of the vinyl gloves you’d use for glassing… highly reccommended.

Yo Doc those little illustrations you do are super nice.Hows the Huntboard project??? RB

Thanks. The joys of cut-and-paste

Thumping along, though had a slight break for some house repairs.

Howzit Spazman, sounds like too much resin in the rope. Too much resin lets the rope slide so it’s hard to keep in place while applying the fiberglass over the rope. what I do is milk the rope to get rid of excess resin, milking is where you put the rope between thumb and forefinger and pull the rope up. You just need to wet out the rope , not oversaturate it, try it you’ll like it.

how do you make the football shaped patches dissapear in to the glass job? I have done 2 boards with glass ons and the base of the patches always stand out green compared to the rest of the clear bottom. Am i cutting the patches too big? I used 2 6oz patches on both sides of the fin.

Possibly never, anytime you get a different thickness of resin & glass your going to get a color differentiation from that thickness. I mean it’s just like water right, 20 ft is a different color that 4000 ft? But if its really dramatic to where you are noticing it, try a different manufacturer or source for resin & cloth. It really should n’t be that noticeable. Heres a dumb question, but, are you sanding & fairing out the patches real good so it has a nice transition. You don’t need but 3 inches of glass all around the fin in 2 layers to make it bullet proof.


Howzit Soulslider, Try using 4 oz cloth or 1 layer of 6 oz and 1 of 4 oz. I usually use 4 oz since the guys on Kauai like a little flex in the fin. Also I don't notice any discolorization except for the rope at the base of the fin. Aloha, Kokua

Sounds like I am doing it right. I cut the basses about 3 inches and make the transition smooth before hotcoating. I actually tried one 4oz and one 6oz on the out side of the fins (twin fins) and the 6-4 combo was alot less noticeable but made the set up alot more flexable. I am woried about this because I am gonna be glassing on one of Halcyon’s flex fins and I dont want to take away from the fin with one of my uggly patches looking bad.

I just glassed on a couple fins to my fish, and while they seem completely bulletproof, I didn’t use much rope at all around the base. If there’s not a smooth transition on the sides of the fins, will it make any noticeable difference in performance, or is the smooth buildup strictly asthetic?

Is sanding a big part in making the fin transition good or is it just how you place te rope and fibergalss?

A couple of things about that -

First off, I am given to understand ( marine surveying and such ) that a fillet joint like a fin attachment is stronger when there’s filler in there. In boat work we use a cabosil mix and something round-tipped to apply it. On a board, the glass rope has the same function but it’s clear. When the cloth goes around a bend, even a small radius bend, it’s using the strength of the cloth far better than trying to do a right angle. This’d probably be more apparent on a high-aspect fin than a keel fin or something like that.

As to sanding - I find that I don’t do enough fin work to really have my fin rope technique down as well as I’d like to, so I wind up sanding quite a lot. I have a couple of pieces of scrap from Corian countertops, with rounded edges, which make nice sanding blocks for that. It might also be the only surfboard use of the profile sander ( ) I picked up a few years ago, 'cos it’s certainly useless for anything else.

hope that’s of use


Howzit Soulslider, I'd say you should get in touch with Halcyon and get his input as far as what would be the best way to glass on one of his flex fins, if anybody knows the answer it's him. Aloha, Kokua