Those weren't there last night

What happened? Those were not there when the fiber glass was expoxied.  There were at least 2 layers of epxoy put on the glass and those were not there.  There were 3 layers of varnish put on after with sanding between layers and those were not there.  This morning those were there.  Is this because of temp and humidity changes while building? When I cut the inspection port in the deck there was an equalization of pressure.

Now what do I do?  Can I give it some light use this weekend? I just finished later than I wanted.

6 replies:

« Previous Post       List of Posts       Next Post »

RE: Those weren't there last night

What am I looking at? Is that delamination, the glass separating from the wood? Are those bubbles, or pieces of glass peeling away? Any chance of a larger picture with more details?

If those are delaminations, what seems the most likely cause to me is contamination that kept the glass from bonding to the wood, even though it appeared to have bonded well. Since you didn't see the blemishes until just now, it sounds as if the glass wet out properly but then peeled away from the wood once the boat was mechanically flexed enough. That would indicate that the contamination is on the wood, not the glass.

The contamination could be oils or water from sweat, silicone from various sources, petroleum products from vehicles or other equipment in a garage, etc. Whatever it is, it's something that was there when you were applying the glass and it got onto the wood, not the glass.

The fix is to remove the delaminated pieces of glass, sand back to bare wood to clean it and reapply new glass. You don't have to reglass the entire boat, just replace the loose glass. Do not put it into the water until you've fixed it. If water gets under the glass (and it will if that's a delamination) that could be the starting point for rot.

Good luck,




RE: Those weren't there last night

   Well, first I did use the boat because I just was anxious to at least float it. The thing that made me feel ok was that the varnish was clearly creating a hard layer.  I will closely monitor and probably not use it again. I would be surprised by contamination on wood.  It was well sanded and prepped.
They are bubbles but I can't tell what layer they are in.  It was hard to get a good pic because the varnish layers was creating a very shiny surface and lots of reflection.

It does appear to be delaminating what is weird to me is that it didn't show up until there were heat and pressure changes.  Is it possible moisture got into wood because of humidity while working.  Because of pressure and temp changes atmospherically, the water in the wood evaporated?

seems like I am going to need to remove some material and then refinish.



RE: Those weren't there last night

Hi MacSideJosh, 

i have been building for a long time (17 boats/25 years) and i had this happen once.

i had recently completed the boat and it was looking all nice (pic below)

and then i took it out on a hot day and 'blisters' developed. (see picture below)

after some consultations and research I did the following:

i wrapped the boat in black plastic and put it out in the sun to 'roast' for a couple days.  the roasting exposed other weak spots, create more blisters. 

i then went over the boat carefully with a dull nail and tested the epoxy for hardness marking with a blue tape any space where the epoxy dented/was not 100% cured

i then pulled off the delaminated glass to the point of good glass/bond and then sanded to prep for new glass

we then put new glass on, feathered it in and refinished and the boat from that point had no issues and we enjoyed it.

We came to the conclusion that i had probably put a bad mixture of epoxy down when the glass was wet out and it had never fully cured/bonded.  when exposed to the heat, the pressure of the outgassing was enough relative to the weak epoxy to debond it.  but fundamentally, it was a bad bond to begin with.  we were pretty clear on the conclusion becuase only the deck was effected after the roasting and the area appeared to correlate with what would have been glassed in one large cup (e.g., one bad mix).

Fwiw….After 7 years of use and a lot of enjoyment and accumulated scrapes and dings, we pulled all the glass off, and  reglassed and refinished  ….the boat looks better than the day we first built it.

Anyway, it was very frustrating when it happened so i feel for you...but it can be fixed and have a happy and long life.



RE: Those weren't there last night

Nicely explained, Howard. It actually makes more sense that the "contaminant" was poorly cured epoxy.



RE: Those weren't there last night

Howard (based on Laszlo's comment) and Laszlo,

Thank you very much!  I have greatly appreciate the forum responses. It is encouraging to know that I will still be able to get years of use out of the board and hopefully be able to get a nice bright finish even after the repairs.

I preface my questions with the following, I am relatively new to SUP adventures so I am doing minimal use of this board right now. I pushed to finish this project before heading off 300 miles away for a vacation and wanted to use the board.  (I did do a first use of the board, based on my comment above that the varnish was holding the water out of the boat/wood and that it does not appear to be under the standing area of the SUP, only on the bow and stern.) 

Questions (with commentary):

How bad it is it to use the board for light use, no big adventures? As long as I am monitoring that water is not penetrating the wood.  This is the first and looks like the last time I might be using the board this summer.  I am a teacher and school starts again soon so I will have significantly less time for use and guess I will have to find time to repair.

The dull nail was used to test for soft epoxy? I am afraid I might have to pull too much epoxy and glass from the deck. I think I had some bad epoxy mix because I was getting to the bottom of the hardner and getting some air during the squirts in the dispenser. 

The biggest frustration is I had put in the inspection port and the deck pads on so I am going to have to pull those if a problem is significant. It appears to be isolated to the deck and not the hull thankfully.  I am concerned it may be bigger than it appears now.  The blisters all contracted when the rain came through here last night and the temperature dropped. Because I am 300 miles from home at a vacation spot I have no good storage options for the boat and can't do further diagnosis of the problem. How much do I need to protect the boat do prevent permanent damage? 

Thank you and sorry for the long and (potentially rambling) response and questions.  I have enjoyed this process and was thinking about my next possible boat project while finishing this one I torn between an oxford shell and sailing vessel of some sort (biggest problem was taking up the garage all summer).  But, I am a bit frustrated now. Your responses and encouragement have been greatly apprecaited. Biggest question is can I enjoy this without causing bigger damage for now and repair later of should I put it on hold longer?

Thank you again





RE: Those weren't there last night

   I think you can safely lightly use it. The glass, epoxy blister is waterproof as long as it is not punctured (that's why it is a blister). When I had the problem I described, I did use it several times before I found time to do a repair. My perspective is enjoy the boat. H

« Previous Post     List of Posts     Next Post »

Please login or register to post a reply.