Repairing soft spot from mast ding

[rhorton1]

I unfortunately ended a great weekend of windsurfing by putting a ding in my Exocet WindSup. There's a crack in the rail that definitely goes through all the layers of fiberglass, and I'll obviously repair that. There are also a few small hairline cracks that will likely get repaired as well. What I'm unsure of is how to repair a soft spot on the deck caused by the mast impact. In the picture, you can see that parts of the fiberglass have turned white from being flexed during the impact. I can press this area down much more easily with my thumb than surrounding areas. The bamboo underneath looks to have taken the impact well and is undamaged.

What I would like to do is drill a few small holes in this area and inject either 4lb or 8lb expanding PU foam into the area, sand off the damaged fiberglass down to the bamboo layer, and then glass over the area with a couple layers of fiberglass. Any thoughts on this proposed repair method?

I looked at the boardlady website and for soft spots it recommends full removal of the damaged sandwich followed by rebuilding the area layer by layer. However, the boardlady repairs are for soft spots between the footstraps. This repair is about 1/4 of the way back from the nose of the board.

Last thing.... I've had some spills on this board before, but this time I was using a mechanical mast base. Any chance that because the mechanical mast base moves so freely the crash did more damage compared to if I had been using a tendon or hourglass base?

[isobars]

[wynsurfer]

That does not look too bad. If the bamboo is undamaged I would not drill any holes in it as this will only compromise the integrity of the bamboo making maters worse. Sanding down to the bamboo and glassing over it with 2 or 3 layers of progressively larger pieces should suffice. At least that is what I would do if it were mine. I would also take a hair dryer and try to peel back the deck pad around the area as it looks like there is damage right up to the edge of the pad. Extend your repair under the pad. Since you caught this in time there is probably little if any water that has been absorbed but once you have sanded down to the bamboo let things dry out real good if any dampness is noticed. Do your glassing on a falling thermometer, never as the day is heating up.

[rollerrider]

The board lady is right because the foam under the impact is now compressed and there is probably a gap between the foam and laminates. Just patching it won't last because it would still become soft in this area that gets abused. But your idea is ok because it is less intrusive and should be good enough at least for awhile. When you drill the holes leave the board out in the sun for at least half a day to be sure no water is present. I believe West Marine has a spray foam you can use. But better be 100% sure it won't react with your EPS foam core. Getting enough foam in there to actually do something will be difficult. Inject it in a center hole and be sure it oozes out of perimeter holes. When you sand the surrounding area be super careful and retain the graphics. Put 2 layers of 4 oz glass over it and graphics should show through. No matter how well a big or wide board is made this area will get crushed from mast hits (unless it's plastic or inflatable).

[wynsurfer]

Does it make crunching noises when you push on the soft spot?

[U2U2U2]

More than 1 way to bake a cake.

I would start with sanding down both areas, if this doesn't reveal any more damage then glass carbon glass over, on the wood it will not blend in so much, unless you brush a stain to resemble the wood grain.

You can always do more extensive repairs , I use 8lb pour foam.

The mechanical base bit, I don't use, it's possible it contributed to the damage or not, could have occurred with tendon or others

I had one Exocet with bamboo deck, no problems, I have seen one that was really bad. Warranty.

It's possible that the wood layer has separated , only one way to find out.
Just from the photo .. I would not be overly concerned with water intake.
Remove the vent screw, it probably doesn't have one...
Let sit in the sun, quick test tape a sandwich bag over the damage if condensation forms, it's got h2o

[rhorton1]

Thanks for the ideas. I will definitely peel back the deck pad and check for damage under it. I have poked around there with my thumb, and the soft spot seems to stop at the pad. No crunching sounds coming from the soft spot, but I do think that the foam is compressed underneath.

I caught the ding pretty quickly and tried by best to suck out any water from the crack once I got back to the beach (just a thimble-full came out). My plan is to mix up some 2-part foam and inject it into the board with a syringe before it starts expanding. From my understanding, by injecting the foam in a closed space, the foam will infiltrate deeper into the board and make for a better support of the fiberglass repair.

My plan to fully dewater the board is to attach my vacuum bagging pump to the crack, leave the vent plug open, and then run a low vacuum through the board. Hopefully this will force a bit of dry air through the board and help to evaporate any water that infiltrated near the crack.

[swchandler]

I would only repair the areas where the fiberglass is fractured and cracked through to the internal foam core. Even if you have some compression damage from the mast, if it's not going to leak, you have nothing serious to worry about. I say this because, the impact area is on the rail far forward on the board where you won't be standing. It would be different if the damage is in an area behind the mast track.

I had some mast smacks leaving dents on a number of boards over the years, and nothing has become of them. With the bottom of the board undamaged, there is little chance that the board will buckle and break through normal use, particularly a light wind design where no jumping is involved.

[isobars]

I see that NSI Hood River, my favorite pad source, is offering 20% off everything this month. Promo code SAVE20.

[rhorton1]

I completed the repair on my WindSUP today. The damage was worse than expected after I pulled back the deck pad. There was approximately a 6" x 6" soft spot caused by the impact, as well as more extensive cracking on the rail after I sanded the paint off.

I used 4lb density pour foam injected through about 10 holes drilled into the soft spot area to bring back the structure. Messy process, but I did not want to tear into the board any more than necessary. Once the foam had cured, I sanded all the obviously distressed fiberglass off the board down to the bamboo layer (about 1 square foot) laid some 4oz fiberglass reinforcements over the area with epoxy, then sanded and painted between rain showers today!

I forgot to take pictures of the repair process, but I do have a picture of the finished product. Two of the foam injection holes ended up being in an unpainted area and show through, but that's just a reminder for me to try and take fewer spills when sailing this board . Overall I'm pretty happy with how it turned out!