eterior AC ply

Hi, i just got some plans for a little 14' gaff style cat boat, and was wondering if there were any reason why i couldn't use exterior grade AC ply wood for the hull since I'm planning on covering the whole thing in fiberglass. I've never built anything bigger than a 34" rc tugboat, and thought that if there was anyplace to get advice on the build this would be it. Thanks in advance.

 

I have built a bunch of small boats with AC. I usually only glass tape the seams. With a couple of coats of paint it will last. The main thing is to choose the sheets that have little or no voids.

 

I agree with gonzo, pick out the best sheets you can find with as few voids as possible, tape the seams and paint it well. Just as a thought what thickness of ply are you considering, it's easy to go too thick then bending it to the shapes you need will be harder if not impossible without splitting it 3/8" is about as thick as i would go, but thats me. Please post pics of the build.

 

Nice to know I am not the only el cheapo builder here

 

If i wasn't "el cheapo" i wouldn't have a boat. Mine is a little 18' sloop I put together about 5 years ago out of AC mostly out of boredom no issues yet (except she's a little tender) so i see no reason to not go cheap, might not be the prettiest but does what i want lol.

 

With the cost of AC plywood it makes it affordable to experiment.

 

You can get AA, AB, AC, BC, and CC. All made the same, just some with better faces. Make sure you note PTS such as BC-P.T.S. which stands for Pluged, touched, and Sanded. All voids are supposed to be filled, exterior
voids you can fill with epoxy if you are going to encapsulate the wood. In true structural applications I always upgrade by 1/8" so 5/8" becomes 3/4".
You cannot usually get it below 3/8" thick ( no 1/4" )

 

There is 1/4" AC

 

Thanks gonzo. I was unable to find it in California and Oregon but I was asking for BC or CC not AC You have just made my life a little more simple as I thought I would have to pay for marine ply in that size.

 

Home Depot and Menard's carry it

 

4 boats and counting with ACX, as noted above, fill the voids and seal everything. I tape the chines and end grains. Void filling is easiest done with a syringe. If you try to pack it in it just leaves air pockets. You can get cheap plastic syringes at the dollar store things if you have them there. I also get my latex gloves at those places and sometimes find chip brushes.

Best of luck,

 

Hi Soggy,
You can use 1/4" underlayment specially produced for use under vinyl flooring. It will have no internal voids, one face will be plugged & sanded, it will have water proof glue in it's plys, and costs about $26.00.sheet. Be sure to ask or specify underlayment grade plywood. Although underlayment is not advertized to "NOT CONTAIN ANY INTERNAL VOIDS" many insiders in the trade know this to be true. Many navel architects are not aware of this insiders info but even so, a navel architect worth his salt will always specify marine grade ply in their designs.
Have a Great Day!
Earl

 

The problem with underlayment, is that is has a thick core and really thin face veneers. It splits is bent too much.

 

Gonzo;
Try buying your underlayment at Menards. It's 5 equal plys--top quality and bends fantastic!

Have a Great Day!
Earl

 

I was thinking of the luan stuff