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Plywood board #2

Posted: Wed Jun 16, 2010 7:37 pm
by lawless
So I finally finished glassing my 2nd plywood board.

This one is made of 2 layers of 1/4" Birch plywood glued up on a rocker table -
glue-up-side.jpg
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I was planning on vacuum-bagging it but the fridge pump I had died, so I decided to hand glass it with UV Polyester resin. I glassed the top first with a single layer of 4 oz. E glass to help hold the rocker then flipped it and put a bead of glass roving all the way around the edge (that sucked, ABS is the way to go). Then I glassed the bottom with a single layer of 4 oz. E.

Top hotcoat sanded
top-hotcoat-sanded.jpg
Bottom hotcoat sanded
bottom-hotcoat-sanded.jpg
Flash edge trimmed
top-flash-trimmed.jpg
done1.jpg
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done2.jpg
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done3.jpg
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I pulled too much resin out of the deck laminate which is why there are white cloudy patches. That's the dry weave showing through the hotcoat. The bottom came out perfect though since I learned not to try and pull too much resin out of the laminate and to wet it out properly.

I got to ride the board a few weeks ago in the ocean in some onshore chop. Worked great, it's a bit flexy but that works well since I usually ride in the ocean and when there's wind it's usually choppy and bumpy.

All in all I'm really stoked how it turned out. It cost about $150 total including the straps/pads/handle. Can't beat that. I copied the outline from a Spleen Rip 138 that my friend has that I've used quite a bit and really like how it rode.

Re: Plywood board #2

Posted: Wed Jun 16, 2010 9:41 pm
by BWD
Curious if you feel like that 4 oz glass gives it any pop.
Have made some plyboards w/o glass, find they have either been massive and stiff or turn into wiggle boards tooo much when it is choppy (or as they age).

Re: Plywood board #2

Posted: Wed Jun 16, 2010 9:44 pm
by daspi
Looks like a successful project!

So one layer each side. What do you mean by hot coat, did you put polyester down first on the wood and then later the layer with glass?

How much does it weight?

I am thinking of doing my second board this way as well. Just finishing up a 1/2" ply board with thinned out tips and sides. Did it with a router, I guess your method of gluing two layers would be almost simpler, especially as you can add rocker.

You mentioned that it remains flexi? Really? I thought the glass will make it much stiffer, some say too stiff for a plywood board with 1/2". Maybe polyester remains softer than epoxy?

Anyway, good job. :thumb:

Re: Plywood board #2

Posted: Thu Jun 17, 2010 6:11 am
by frankm1960
Excellent looking board :) What are the dimensions?
Just wondering why you didn't add a concave to the board, most boards have that. I don't know what it does for a board though.

Re: Plywood board #2

Posted: Thu Jun 17, 2010 7:04 am
by gbleck
Hand layup with concave would be harder. You could do the bottom first laying the glass down on the plastic and place sand bags on the core as it dries but that wouldn't work on a light cured resin unless you did the table out of say 1/4 inch plexiglass.

Nice board. Loving the price. :)

Re: Plywood board #2

Posted: Thu Jun 17, 2010 6:25 pm
by lawless
To answer some of the questions -

Yeah, the glass helps the flex quite a bit. The 1/4 plywood is more like 3/16 so 2 layers is really closer to 3/8 thick rather than 1/2. A single layer is easy, keeps the weight down, gives it decent flex and keeps it all waterproof.

A hotcoat is a filler coat of resin only after you do the first laminate layer where you wet out the glass on the board. If you use too much resin on the laminate step the fiberglass will float in the resin.

I'm not sure of the exact weight, it's not exactly light though.

I've got a 3/8" thick plywood lightwind board that I glassed also -
viewtopic.php?f=107&t=2353837&p=568768
Solid 3/8" all the way out and it also has a single layer of 4 oz. glass on each side and is super stiff. The stiffness is more a function of board thickness and this one is a bit thinner overall and the tips/rails are way thinner and the flex feels good.

Yes, polyester resin in not as stiff as epoxy. UV poly cures in 15 minutes in full sunlight so you can feasibly build a board in 2 days from start to finish. That's about it's only benefit. Vacuum bagging and epoxy would give a much better result.

Dimensions are 138 x 44

I didn't add a concave because it was a hassle. My plan was to make a few of these for my friends and I wanted it to be simple, quick, easy and cheap.

Lessons learned for the next one:
1. Find ABS for the rails or use poured epoxy.
2. Vacuum bag it, saves a ton of time, effort and sanding

We should have some wind in the next week so I'll post a more detailed ride review if I get a chance to ride it again soon.

Also, something that made it really easy was buying stainless snowboard inserts:
Image

They were $5 for a 16-pack:
http://boardcrafter.com/component/page, ... /Itemid,1/

I just drilled a hole to their depth with a forstner bit and filled it with epoxy/glassfiber mix and set the inserts in then glassed over them. They even come with plastic caps so you can sand them down and glass right over them then drill them out when you're done with a countersink drill bit. Super easy and looks professional. Way stronger than brass inserts too.

Re: Plywood board #2

Posted: Thu Jun 17, 2010 8:48 pm
by frankm1960
Excellent :) I never thought of using snowboard inserts and eliminating the concave would definitely make it easier.

I've got a LF recoil, 133 x 40. Not much concave in the board, fairly flat. So maybe a concave it not all that important?

In any case I'm looking forward to reading your ride review on the board :)

I know where I can get some marine grade ply, 1/4", so I'm considering making something for myself if yours works out.

I kite in mostly small chop waters with occassional small waves.