White small dots after a year???

Greetings Folks,

My WD12 Hybrid has developed these white small dots under the fiberglass after about a year of use and car-top transporting. They show up in random areas, but this pictures shows them best.  1) What is this from? 2) How do I fix it? and 3) How do I prevent it from happening again?

Many thanks in advance!


6 replies:

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RE: White small dots after a year???

Hi NM, 

i looked at your picture and it brought back some memories of a similar issue i had on a dark hulled strip kayak a number of years back.  my picture taking was not very good back then....but i copied one of the pictures in below.

it was a very frustrating experience and we did not ever really perfectly figure out what was happening but it was highly correlated with dark parts of the boat left in the sun where it clearly got very very hot.   the epoxy, due to heat and/or less than a perfect cure, got soft and the heating of the wood created outgassing /pressure that basically pulled the epoxy away from the underlying glass causing white spots (this is what happens is you pull a solid glass fibre through soft epoxy).  like your boat, there were some darker strips than others and the problems that developed nicely aligned with the darkest (e.g., the parts that got the hottest in the sun).

there were two fixes we applied:

1) tactical fixes were applied at the end of the season where we sanded out the damaged glass and fared new glass in.  the next two pictures show the fix in progress and then basically the after picture which shows that the tactical fix cosmetically worked very well.

every couple seasons i would make some new tactical repairs.  but it was very frustrating.

2) after about seven years, i decided on a more permanent fix which included complete removal of all the glass and old epoxy and reskinned the boat with new glass using a different epoxy system (i think it was system 3) that has a reputation as being more heat resistant than MAS (which was the original epoxy used).   Joey Schott, now of TurningPoint Boatworks, worked with me on the project and has a lot of know how about the heat and issues and worked with me on the reskinning with a different epoxy system.  so i would definitely suggest a consult with him if you can get it.

while it was very frustrating, the final fix has not had any problems since it was completed and that was about 4 years ago now and the boat has never looked better. 

my only other thoughts on the whole thing was that it was clearly more of a cosmetic issue than a structural issue but it became kind of a big maintenance suck.  but the amazing thing about these boats was the ability to finally address the issue and get the boat back to new shape.

fwiw, these days, even with the new epoxy system, i do try to not let the boat sit in the sun and if i have to park, try to find some shade.

my other solution was my latest boat...which has a white stained deck.  it stay noticably cooler than any of my dark boats when sitting in the sun....so i hope to see this year with a full season how it behaves in the summer.  but a lighter color clearly does not heat up the way dark brown does.

hope this was helpful....


RE: White small dots after a year???

   Good morning hspira. 

1st, beautiful boats! Thanks for responding.

This is a bit frustrating after putting in so much work. If sanding off all the glass and and putting new glass on in hopes it doesn't happen again is the only option, well, it'll be a "feature" for a while. I made a WD10 hybrid for my wife and it has some of the same "features" as well. Maybe in 7 years when I am out of other woodworking projects 😅

One other thought came to me... My home and shop are at 9500 feet in the mountains. Maybe altitude gains ad losses through our travels is part of the challenge? I really don't know what's happening for sure.

All the best and happy paddling!


RE: White small dots after a year???


i suspect large changes in elevation ....9,500 feet is a contributing factor.  to summarize what i recall of the conversation with Joey....

the white flecking is when some kind of pressure is being exerted on the matrix (epoxy, wood, and glass) and if the glass and epoxy expand at different rates and the epoxy has a weakness relative to the glass, it will start to pull and fracture and/or create voids in the epoxy (hence the whiteness).

sources of pressure are thermal expansion of the matrix and outgassing.  sources of weakness for the epoxy is a poor cure and/or heat/or just a not very strong epoxy formulation.

big elevation changes would definitely act like outgassing or cause the wood to potentially swell....so its another source of expansion/contraction - pressure on the matrix.

while these effects are very very small, they accumulate over time and you start to see this flecking....which, like you said, is more of 'feature' for now.   when you get tired of this feature, you can choose how to act. which is why,  similar to your logic, i took my time and did not rush to a repair.

the only other suggestion i can offer is to push a dull nail into the skin around these flecks.  if you can leave a dent/depression....that would point to an epoxy cure problem that could be a contributor to this (which in my case, it was and what lead me to redo the whole hull after 7 years).   if its all solid, then its just the accumlated effects of the expansion/contraction finding the weakest link (where the heat builds up) which is leading to the flecks you are observing and you can simply address it when you feel like it.

beautiful work on your boats.





RE: White small dots after a year???

   Hi NM,

One response to this...

"If sanding off all the glass..."

It's actually much easier than that. A heatgun, pliers, putty knife, and gloves make pretty quick work of removing fiberglass. And with a strip boat once it's off you can sand any residue or dings  pretty aggressively and the boat will look like new.

I'm just finishing a re-glass on a plywood boat. The wood on the hull had water stains so I'm painting it.




RE: White small dots after a year???

Howard and Dan have great suggestions for how to fix this so I don't need to say anything about that, but as for the cause, it looks like classic fatigue stress. Older boats that get used a lot show this all the time. The original WD12 prototype at CLC, the one built by Eric Schade, actually had its seams turn white tears ago from all the use it got during demos. My WS12 which is a couple of years younger and inly used by me is starting to show the first signs of this along its cockpit seams.

Fatigue is caused by repetitive bending of a material. if it's too thin or brittle it will crack. The white areas along your joints are where the joint between the pieces of wood flexed enough times to crack the overlaying glass.

For some reason, probably the thermal causes mentioned above, those areas had less support than they should have so that's why the normal flexing caused the glass to fatigue there and not elsewhere. It could also have been caused by a void inside the joint or a crack in the wood acting as a stress concentrator.

Whatever the cause, the fix is to replace the glass, just as they told you above.



RE: White small dots after a year???

   Thank you all!

Dan, I like your tip on pulling off old fiberglass. It makes it sound less daunting for when the time comes. For now I'll keep an eye on it and make sure it doesn't get bad enough to be a structural concern.

Laszlo, I appreciate your insight on fatigue. We do use our boats quite a bit so getting some wear and tear is expected. I think they're getting more abuse on the J-racks on top of the truck than in the water. We have gone over 5000 miles with them this last year and hope to use them a lot again this year. I have limited options for transporting them since we often are pulling our 5th wheel when traveling.

Thanks again all! Cheers!