69175RE: [bolger] Re: Plywood question
- Jan 10, 2013
There is a school of thought that suggests that ‘common materials’ are not nearly as good as they used to be. While I’m not the man I used to be (and probably never was), I think the quality of common plywood has deteriorated over the past ten or 20 years. A long time ago, I built boats from AC fir plywood. It was not Ideal in that it checked, had occasional voids, and the ‘footballs’ would print through any finish including fiber glass set in polyester resin (epoxy was unknown back then). But AC fir was made using 3 equal sized plies, was waterproof, fairly light, and the sheets were square.
Around here, common fir plywood has been replaced with pine plywood. This plywood is quite heavy and checks worse than fir. Some big box stores offer a proprietary brand. In general, these have very thin exterior plies and need to be tested to see if they will delaminate when exposed to water. I have also found that a significant number of plywood sheets are no longer square, and I now check each sheet.
It is certainly possible to build a boat using ‘common materials’, including big box materials, glues other than epoxy, polyester resin over fiber glass, and latex house paint. The boat will float and give its users some pleasure, but will not look good or last long. Given the fact that time spent building a boat has value and that the value of the time probably exceeds the value of the material, it doesn’t make much sense to skimp on materials. To quote Pete Culler, good things are expensive and a lot of us think boats are very good things.
From: email@example.com [mailto: firstname.lastname@example.org ] On Behalf Of james fry
Sent: Wednesday, January 09, 2013 11:58 PM
Subject: Re: [bolger] Re: Plywood question
I've built just three boats in my life; the first was a canvas covered canoe I built with my Pop-pop when I was 14. While reskinning for the third time, I gave it several coatings of W.E.S.T.
The second was a Popular Mechanics plan called Maximus that I built when I was 27. I used W.E.S.T. again and laid glass strips on the joints and along the keel. Plywood used was 3/8 A/C fir EXT.
The third was Mr. Redmond's WHISP. I was 29. Again I used W.E.S.T. and glass strips on the joints. The plywood used was 1/4 A/C fir EXT.
The canoe is still used at family reunions back in PA and the runabout and Whisp I brought with me to S.W. Fla. They are also still being used. Oh, do the math. I'm 61 years old. There's no reason to get plywood made of magical trees that have been licked by a Wallaby or have the sweat off of a camel's tail in its' grain. Common woods, used and prepared properly will last a nice, long time.
From: Mason Smith <goodboat@...>
Sent: Wednesday, January 9, 2013 9:21 PM
Subject: RE: [bolger] Re: Plywood question
My two cents on this plywood business is that I like to use oukoume (I don’t have experience with meranti but think it would be better than oukoume) rather than fir for a couple of reasons. More laminations for a given thickness, for one. But the main one is that I don’t like to glass above the waterline if I don’t have to, and certainly not inside, and fir will check, for sure, if you don’t glass it. That operation throws out any saving in buying fir. Buy oukoume or meranti and don’t glass unless you must for abrasion resistance on the bottom. Put some trust in a coat or two of epoxy and two or three of good paint.
68 North Point Road
Long Lake, NY 12847
518 624 6398
I haven't posted here for a while, but would add that my Workskiff 18 is built out of a marine grade fir, but encapsulated inside and out with epoxy set in glass. (I will also admit to treating it with antifreeze prior to glassing). so far, 5 years later it is still in like new condition. I would not want to put my blood and sweat into a project and then have it delaminate. You could purchase a chunk and put it through the boil/dry cycle a few times. That saved me a bundle over the years when dealing with various grades of exterior plywood.
Having said that, in these smaller boats I think it is worth the leap to Joubert Merenti, or an okoume ply. The Merenti is seems worth the piece of mind to know that your boat won't delaminate in the middle of a pond on a cold winter's day, and that in itself seems worth the extra $80 bucks.
My last build was not a Bolger boat, but I did use BS1088 Okoume for the Michalak Vireo. It was beautiful, and came in very light at 56 pounds with only the bottom glassed. It is subject to denting, but handles well. the merenti splinters more when cutting but provides a harder surface. Better for where glass won't be used.
Ok group. FIRE AT IT!
David Jost, Boston , MA
--- In mailto:bolger%40yahoogroups.com, "steven_dantonio" wrote:
>plywood. Has anyone used Georgia-Pacific's "Dry-Ply plywood". It looks like it's treated so I'm a bit hesitant unless I can find out some good information regarding it's gluing properties.
> I'm just about ready to start on a Mayfly 14 and was shopping around for
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