Would this layup schedule work?

DualCore

Seaman Apprentice
Joined
Mar 19, 2009
Messages
30
Hi everyone, sorry to bring this up again I just really want to make sure that I have this correct before I order anything (soon I hope). I know I?m probably over thinking it and making it more complicated than it needs to be (like usual) but I know you guys can set me straight.

I am still trying to decide between Epoxy and Poly, I have a pretty good idea of how I would do it with Poly so now I want to understand how it would work with Epoxy so I can try to decided which method would best fit my project.
So my question is does this sound like a workable layup schedule for a 15ft tri-hull using Epoxy resin:

Transom and stringers:

Glue transom to hull outer skin with Epoxy paste
4? tab of 18oz roving (2? on hull)
8? tab of 18oz roving (4? on hull)
complete cover 18oz roving (6? on hull)

Sole:

Coat bottom with Epoxy (should I also use cloth?)
4? tab of 18oz roving (2? on hull)
8? tab of 18oz roving (4? on hull)
complete cover 10oz cloth (Or would a different cloth/roving be better?)

Would this work? Am I missing anything or is there a better combination of materials? Is this enough glass or should I add a second complete cover on the transom and/or stringers?
 

erikgreen

Captain
Joined
Jan 8, 2007
Messages
3,105
Re: Would this layup schedule work?

If you like or already have roving, use it, but otherwise I'd recommend biaxial fabric, either with attached mat (like 1708) or without. It's easier to work with and actually stronger, or more precisely it gives strength in more directions than two like roving does.

The tabbing amounts look fine, as does the overlap (that's actually a really big overlap, but that's ok).

For the deck, you can coat the bottom in epoxy and it'll keep waterproof 20 years. If you want longer or a stiffer, stronger deck you can put cloth in it.

10 oz is ok for the deck, but it's actually heavier than you need unless it's structural. If you're using the glass for abrasion resistance you only need about 6 oz cloth. Be aware in either case you'll get a pattern showing through, which you may not care about. To avoid the pattern you can fill the deck with fairing compound or use a surfacing veil, light mat, or very light cloth with a tight weave as a second layer.

Probably a second complete cover on the transom and stringers would be overkill... one is more than enough unless your boat is bigger than 25 feet or you expect to abuse it badly. A lot of people don't even fully cover the stringers once unless they're foam core or hollow types.

Epoxy for these uses will give you a very strong bond to the existing glass even if you make mistakes in prep for the most part... it's still possible to do a lousy job, just harder.

Poly will be a bit cheaper, and if you do the prep work right will be strong enough for this. Obviously you'd need to use mat in between layers with poly, and you'd have to use mat and/or cloth anywhere you cover a surface with it... poly won't work as waterproofing without glass.

Erik
 

DualCore

Seaman Apprentice
Joined
Mar 19, 2009
Messages
30
Re: Would this layup schedule work?

Thanks Erik,
I was thinking about using roving since there are some good deals on remnants from ebay (thought it might help offset the higher cost of the resin...).

What about using the 18oz roving for the tabbing and 17oz biaxial for the cover, would that be any better?

I guess I'll have to price it out and see how much difference there would be between getting the box of roving from ebay vs ordering everything.

If I went with all biaxial would I use 17oz (without mat) for both tabbing and complete cover? Would the tabbing amounts below still work?

Thanks a lot for all your help, I couldn't do it without you.
 

ondarvr

Supreme Mariner
Joined
Apr 6, 2005
Messages
11,527
Re: Would this layup schedule work?

The roving you're looking at is typically scraps of random size, so the finished job may look like a patchwork quilt, it still works, just takes longer.

1708 works very well with epoxy and the small amount of CSM attached to it makes it easier to use than without it, it also works very well with polyester.

If you really want the bottom of the ply waterproof, use glass there too (light cloth).

I would go thicker on the inside of the transom, a second layer will help a great deal.
 

DualCore

Seaman Apprentice
Joined
Mar 19, 2009
Messages
30
Re: Would this layup schedule work?

Thanks guys, I think I've got a pretty good understanding of how to proceed with the glassing on my boat now. Now I just need to finish the grinding... :eek:
 
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