Quad Fin Tail Repair

General Discussion
1

There are two questions in this thread.

I recently put a crack in the tail of my board, approximately 6 inches up the rail from the tail, through both FCS plugs and extending about 16 inches on the same angle as the plugs. The two plugs also came very close to pulling through the board, so the traction pad has to be removed as well.

I was using FCS H-2 Medium fins, both front and rear and was powering through a large cutback at the time of the crack. The board stuttered and I thought I broke a fin, but it was actually a very large crack. I have never broken a board before and this is my first quad fin, only about 1 month old. Is it possible that the extra cant built into the H-2’s puts too much force on the rail and that caused the crack?

I am going to salvage the traction pad, but since it is an epoxy board, are there any specific glues or epoxy’s I should use to adhere the pad?

Thanks for your help

2

Wow! a 16" crack from a cutback… I’ve broken a cheapo composite future rail fin on a backside hack, but this sounds like a poor glass job to me.

Is the board pu pe with a single 4 oz bottom?

Did the crack initiate on a front or rear fin?

Any chance the crack was started before (rock, reef, etc.) and then split open with the cutback?

3

Yes, 4oz glass. I weigh about 185lbs and 6’3".

The crack does look like it started at the rear side fin, but I can’t be certain. I didn’t crash right away and continued to surf for a couple more turns and that might have increased the size of the crack.

Any insight on fin choice as a cause or what adhesive to use for my tailpad?

4

First the glue for the pad. The foaming polyurethanes ( Gorilla, Sumo, etc)

will stick the pad back down. just don’t use too much and push the pad

down firmly as the adhesive cures. You might get some foaming out the edges,

but you can trim that off.

This is an epoxy board with one 4 oz. on the bottom? What kind of foam?

FCS installs in some foams can be tricky. Does the H-Pattern go through

to the deck? It sounds like the plugs weren’t supported enough, either from

too little glass on the board or weak foam or improper installation.

Thinking about the change in load from fin cant is perplexing. Since the fin

stays more vertical during a turn, is it “capturing” more water? If so, it

would seem like it would “hold” better. I’ve ridden those fins, and didn’t notice

a profound difference in their level of grip. They do go rail-to-rail easy.

Definitely something to think about. FCS did a lot of research on that fin set,

so I think I’ll ask them.

Mike

5

The foam is a US blanks PU (red density) and it’s glassed with 4oz bottom and 2 x 4oz on the deck using Resin Research epoxy. The H Pattern (plugs) do not go right through to the deck.

Here are a couple photos of the damage.

6

IMO it’s a case of poor installation. FCS is great system when installed CORRECTLY.

The H-Pattern is CRITICAL in preventing just the type of failure your board shows.

FCS has a testing device that puts side loads on fins, I’ve seen their data, and the

H-pattern improves strength dramatically. Almost every FCS failure I’ve ever seen

was caused by deviating from their instructions.

Was the oval patch in place also? Imposssible to tell from the image(for me). If not,

that contributed to the failure as well. Are you sure you didn’t hit anything or push

down hard on the board while waxing or something?(that’s where the cant on the fins

could put more stress on the plugs)

I did talk to FCS yesterday and they said their flow-tank testing, etc., showed no

increased loads with the H-2. And the quad sets are going very well.

Good luck as that’s going to be a fun repair.

Mike