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Part 4 of Ross's Famous Surfboard Repair Series

The Mother of All Surfboard Repairs

This page documents the repair of a10' longboard that suffered a severe case of deck delamination. After 3 years of heavy use the deck was getting very loose. I had the board professionally repaired using conventional methods. The goal was to get one more season out of it. I did. But by the end of the season the filler was cracking and the board filled up with water. It was getting heavy, perhaps 32 lbs at the end. Using a claw hammer I removed the resin/microballoon filler which was over two inches thick in places. The removed pieces weighed about 8 lbs. The blank was very water soaked and took 3 weeks to dry with a fan blowing on it at all times. The first two pics were taken at the end of the dryout period. Last update to this page: April 21, 2007.

I am using 4 lb density two-part polyurethane pour foam. This is my second experience using the pour foam. I used 8 LB density foam on the first attempt (another board), but felt the foam was too brittle. This is similar stuff, but it expands twice as much. It is still pretty hard. The foam is the consistency of honey when first mixed (see the center section where it still looks wet). About 45 seconds after mixing it begins to slowly rise to around 16 times its liquid volume. It can be smeared around a little when first poured, but seems to work best when just poured in thin lines.

It looks awful! I just keep mixing 6 tablespoon batches ( 3 spoons of part A to 3 spoons of part B) and pouring it in lines. I don't have a lot of working time with this stuff, so small batches are a safe way to go. The goal is to get a build up that is above the deck line so it can be planed down flush. 75 percent of what you see here will be sanded off.

All done! It took about an hour. If I mixed larger batches, I could cut the time way down, but with larger batches it takes more time to mix to get a consistently even mix. The foam's main commercial use is for flotation in boat hulls, but it is also used for many other things including taxidermy. The cured foam can be shaped and tooled. I will use a 9" grinder for initial smoothing. With a 100 grit pad it will only take 5 minutes at most. It makes a major mess, so I move to the remote reaches of my back yard. A power planer would probably work well also. The foam is a little too tuff to take down an area this large by hand. It is much tougher than the white foam the board was originally made from. This may be a problem. I could probably sand it down with 36 grit sandpaper on a block, but I would sweat off a couple of pounds in the process on an area this large. The 2 quart kit of foam cost about $15 from U.S. Composties in West Palm Beach. I used about two-thirds of the kit.

The foam hardens in a few minutes and cures in 24 hours. It weighs a small fraction of what filler made with a microballoon/resin mix weighs and is not as rigid, so the board will still have some flex. At this point the process must still be considered experimental. A search on the Internet did not find any mention of pour-foam use for surfboard repair. I am sure folks have tried it, but apparently they didn't publish their efforts. So far I have have mixed results with pour foam. On another board that I used this same technique, only with 8 LB density foam, the foam cracked and delaminated in a 12" section within a week after the repair. I didn't let it cure. This time I will give it at least 2 weeks to cure before using it. Also, I hope the 4 LB foam will have a little more flex than the 8 LB density foam. And, of course, the patch will only weigh half as much.

A patch this big (or even a fraction of this size) made with the white microballoon/resin mix for filler is going to ruin most boards. The microballoon/resin mix is simply too heavy and too rigid for large repairs like major delamination and extensive damage from a broken or buckled board.

The pics below are after I ground it down with a 9" grinder and 100 grit pad. The 100 grit goes a little slowly, but gives less risk of cutting a real deep gouge. After I got it close, I sanded for a few minutes with 36 grit on a 10" wood block with long strokes. I then finished it off with 50 grit on a 10" block, again with long strokes from end to end of the patch. The bubbles you see are where I just poured some more pour foam to fill air pockets. Only one hole was bad enough to need foam, but the goal is to keep it as light as possible so I filled all the significant holes with foam. I have a few dips and bumps, but it is quite acceptable compared to the rest of the banged up deck.

After sanding with 100 grit on a block, I applied two coats of interior/exterior light weight spackling to seal the pores and small holes in the foam. I waited 24 hours between coats and sanded lightly with 150 grit. I was going to use a slurry made from 50% resin and 50% microballoons (the white powdery stuff). However, research revealed the spackling is what the pros use for building new epoxy boards. I am going to laminate using epoxy resin even though this is a polyester board. The epoxy resin is easier to work with and stronger, but costs twice as much as polyester resin.

The board weighed 32 lbs when I first started this repair job. After applying two coats of six-ounce cloth to the patch areas, the board weighed in at just under 20 lbs. Next, I laminated the entire mid-deck area (from the nose pattern to the tail) with one layer of 4 oz cloth, fully lapping the rails to the bottom of the board. This really smoothed out the patches and hopefully will add just a touch of extra strength. Since I am down almost to the boards brand-new delivery day weight, the small amount of weight that one layer of 4 oz cloth adds seemed like a reasonable approach. A new board like this would cost $800 to $1000 retail, so I want to make it as close to functionally new as possible. Materials are cheap and my time was also since the surf had been very poor lately.


Just about done. This pic is the day after the final resin coat (hot coat) was applied. All that's left is some final sanding and a coat of UV protection clear coat or white paint from the nose-pattern to the tail. The paint would be to protect the epoxy and pour-foam from ultraviolet light damage, not just for looks. The resin I am using is boat-quality epoxy without UV protection additives like you may find in more expensive clear surfboard-quality resins. I'll use Krylon Fusion if I paint it since this coating doesn't require priming and glosses very nicely without final wet sanding and polishing. Krylon Fushion dries to touch in 15 minutes, but takes 7 days to fully cure. Read the label. Your should let the epoxy cure for a week or two before using the board after a major patch like this. The board now weighs just under 22 pounds with a huge fin. That's a little bit heavy, but OK for a board this size. That's also a 10 pound reduction from when I started the repair process, and now I have 3 layers of cloth on the deck (and 7 layers on the mid-board rails).

The repair was completed in February, 2004. It is now June, 2005, and the board is holding up just fine. Based on this experience, I think we can consider the pour foam method as a viable way to restore a badly damaged board to useful life. It isn't pretty, but it rides just fine. So far, there is no detectable deterioration in the patched area at all, but the epoxy has darkened to a very obvious yellow tint.. I was going to paint the deck to shield the epoxy from the sun's ultra violet rays, but never got around to doing it. This is now my favorite small wave board. I don't risk taking it out in surf above 4 feet. No sense in pressing my luck when I have 9 other boards to ride.

Several weeks after using the pour foam, I attempted to use the remainder for a patch on another board. However, one of the two-part ingredients had crystallized. The pour foam has a VERY short shelf life once opened, so use it all up quickly.

Fast forward a year or so -

We took this board to Nosara, Costa Rica. I don't know if it was low pressure in the baggage department or the big waves in Nosara, but the pour foam pulled away from the white core foam in a large area of the patch. When I sliced the deck open, I discovered that the bond of the cloth laminate to the pour foam was solid. Almost all of the pour foam peeled up with the deck. The original core foam was just too deteriorated to hold. The bond did not separated, it just lifted the top most layer of original core foam. I am going to try once more. This time, I am either going to router out the old foam to an even depth in the entire patch area and glue in strips of 2 inch thick insulation foam (like the stuff epoxy boards are shaped from). Or, I am going to sand down all the deteriorated core foam, lay a base of 4 oz cloth, and then rebuild with pour foam just as I did in the first place. Right now I am letting the board dry as the foam felt a little damp in a few spots. It will costs about $70 in materials to do this and take 4 or 5 hours total work. This is such a nice board for small wave nose riding, I think it is worth the effort. I have another 10 footer, but it rides like a barge compared to this board. I'll take some pics of the process.


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