shearwater tape and glass question

I'm building the Sh Sport Hybrid.  The plans call for fiberglass tape to be laid down along the 3 seams of the cockpit area, followed by laying down a sheet of 4 oz glass over the whole cokpit.

I'm wondering if it would be OK to reverse the order- laying down the glass sheet, followed by the tape along the seams?  The reason would be to avoid laying glass over the thick edges of the tape, which is a setup for struggling over air pockets along the thick tape edges.

Would this alternate oder of battle be sacrificing strength, or give some other problem I've not considered?

Thanks for your consideration while you could be plucking feathers off a turkey or peeling potatoes.


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RE: shearwater tape and glass question

Hi Hickory,

Hmm, those are interesting instructions.  I built a Shearwater 14 and I just looked in the manual and the interior hull fiberglass schedule only calls for fiberglass tape in the fore and aft compartments (no fiberglass cloth) and only fiberglass cloth in the cockpit (no tape).  I agree with you that putting down tape and then cloth will be an issue and cause a nightmare of air bubbles, etc. along the edges of the tape.  If you're going to do both the tape and cloth I would definitely do the tape on top. 

I did cloth over the entire interior of the Shearwater 14 hull with no tape (different than the instructions) and have had no strength issues so far.

Back to plucking feathers! 


RE: shearwater tape and glass question

The SW Sport Hybrid does depict taping the seams of the cockpit first - before adding the cloth. I just did it last week. I imaging that the cloth over the tape will make for a smoother cockpit floor because it does not even call for filling in the cloth with additional coats of epoxy. I checked with CLC and they said that it was optional and would obviously add a little extra weight to the boat. I decided to add an extra coat to fill the cloth.

It does take some effort to get everything wetted down. Even then I did not see a couple of small air bubbles until after it had cured. Overall it was not too bad though.

If I had to do it again I'd do what was called for when I built my Night Heron  Hybrid where the tape is presoaked in epoxy. Of course, with the NHH is was essential in that particular process. However, in this case, adding that step would make the process a bit easier, I think. 

I have just put down the last coat of epoxy on the outside of the hull and am getting ready to plane the sheer clamps and installing the forms.

I have another question about form #6 which I'll post separately.

Ready to peel potatoes for mashies!


RE: shearwater tape and glass question

Thanks for the input Kathy and Chris.  I found an older post addressing this issue, with varying opinions.

One esteemed contributor (of catfish trapped in the boat fame) suggested to go with what the designer specified- that being tape the seam followed by glassing the entire cockpit.

Another said he checked with John at CLC-"I corresponded directly with John Harris who told me that the CLC demo boat does not have the cockpit joints taped and it has stood up well to the "bumper boat" treatment.  His recommendation to me was to eliminate the cockpit tape."

Here is the link to that thread-

I'm still deciding, but I think I'll go ahead and glass the cockpit, followed by taping the seams before the epoxy has cured.

Cheers, and now back to cutting up parsnips.


RE: shearwater tape and glass question

Based on John's assessment I would have skipped taping the cockpit all together. :)



RE: shearwater tape and glass question

I built a SW sport hybrid, and a duckling. In both cases I taped first, whilst the fillets were wet, then glass whilst the tape was wet. I did get a couple of little bubbles, but no real issue. If you put tape on top, you will get an unsightly ridge which you would sand off, with the risk of going into the glass. I'd go with the manual on this one.

RE: shearwater tape and glass question

On my SW Sport Hybrid, I did it as the directions indicated.  After the tape cured, I hit the edges with some 80 grit to just knock it down a bit, then glassed over the tape.  Worked out well.

RE: shearwater tape and glass question

I went ahead and did the sequence of taping the seams, followed about 4 hours later by glassing the entire cockpit (not bulkheads), as the instructions suggest.

While placing the glass over the thick tape seemed like it was going to be problematic, it really wasn't.  The 4 oz glass is pretty compliant, as it lays over the bump of the tape edge, so I didn't have much problem with air bubbles.

Overall, I favor strength and function over weightsavings and perfection for this craft, which will likely see some Pacific waves in its career.  My wife comments that its kind of like me- not so optimized for weightsavings and perfection.

Thanks for everyones input,


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