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Re: Material: Is marine plywood necessary?
By:Tyler Dunn
Date: 1/15/2011, 2:31 pm
In Response To: Re: Material: Is marine plywood necessary? (Paul G. Jacobson)

Thanks to everyone for all of the comments. I've seen many of them pop up in my email and I thought I was getting them all. I came back online to thank the people who had responded to my question and found that there is even more information for me to digest.

After careful scientific analysis (meaning I asked my son which design he liked the best on Tom Yost's site) we have decided to put together a SOF sea flea. Depending on how things go I'll build another boat for my daughter.

Thanks for all your input. You must really love kayak building. I hope we enjoy as much too.

Tyler

: Do you have plans for one yet? Which design have you selected?

: If you have not yet fixed on a plan, let me suggest you look at
: some skin-on-frame designs, and then "skin" them with
: panels of thin plywood. It is a cheap and fast way to build a
: boat your son can enjoy this spring. You won't need any
: fiberglass for these, either. Just epoxy. If you use marine ply,
: you can skip the epoxy.

: For a plywood boat for an 8-year-old boy you could probably save a
: bundle and not buy the fiberglass cloth. The plywood does not
: need the added strength, and two coats of epoxy resin (without
: the added glass cloth) will still encapsulate the wood
: completely. You'll want resin and glass strips (cut from a piece
: of glass cloth, not the expensive, prewoven tapes) for the
: seams. but you should be able to keep down your glass purchase.
: By reducing the amount of glass you also reduce the amount of
: resin needed to cover it, and the time spent in multiple fill
: coats. You also reduce your sanding considerably. And the weight
: will be about 2 to 3 pounds less.

: OK. but take the added benefit if it comes your way :)

: For most of our purposes marine plywood is not necessary. There are
: some designs which call for some bending of the plywood, and
: these designs were based on using certain metric-sized, marine
: plywoods. Anything thicker, or not meeting those specs, would
: crack when folded. Some of the metric-sized panels are larger
: than our standard 4'by 8', and there are designs which make use
: of the extra few inches. You can scarf panels to get longer
: ones, or build a boat a few inches shorter than the original
: design.

: Marine plywood goes back to a time before epoxy. It was developed
: as a material to replace solid wood for planking wood boats. It
: was designed to take the abuse of a solid board, which it would
: replace. With a good-looking veneer face it would be less
: expensive than a solid hardwood board, but be just as pretty.
: Great fro trim above the waterline, as well as planking below
: the water line. Theoretically it should be able to be immersed
: for all of its life without delaminating. In order to predict
: that kind of life expectancy, they test samples in hot water and
: pressure cookers, and such. You pay more than you would pay for
: construction ply, but you should expect to get a (slightly)
: higher quality material.

: Since marine ply is already resistant to the effects of immersion,
: you don't need to cover it with epoxy. If you use a truly
: waterproof glue for the seams (epoxy, urethane, polyurethane,
: phenolic, etc.) you can simply prime and paint the boat with
: marine enamel. Small boats which are not stored in the water can
: use paints designated as "topside" paints, which,
: while the cans state "should not be used for immersed
: surfaces", work really well.

: Is it worth the added cost for marine ply? Not always. but
: sometimes using it can actually make the whole project cheaper
: because you save on construction time and cost of epoxy resin.
: Where the plywood is covered in glass cloth for structural
: reasons you would keep the fiberglass, of course. Is marine ply
: absolutely necessary? Generally, no. At least, not if you are
: going to completely seal conventional plywood under epoxy.

: :I

: Personally I think that the Baltic Birch panels, with their many
: thin veneer layers are strong and pretty. Not much difference in
: price. In fact, some Baltic birch is more expensive, but it is
: easy to find small panels at the local Menard's and Home Depot.

: A lot of decisions about what materials to use were previously
: based on choosing from locally available stuff. If your
: lumberyard didn't stock marine plywood, you didn't have the
: option to choose it. With the internet we can now order things
: from more 'mail order' sources than were ever available before.
: The shipping costs may be high, but people are experimenting
: with more materials--and if you want to send out for some marine
: plywood, then go for it. But if you want to build a boat which
: will last at least 15 years, and maybe 50 years with some care,
: go ahead and use locally available plywood.

: Good luck wiht your project. Hope this helps.

: PGJ

Messages In This Thread

Material: Is marine plywood necessary?
Tyler Dunn -- 1/9/2011, 8:18 pm
Re: Material: Is marine plywood necessary?
Dave Gentry -- 1/9/2011, 8:25 pm
Re: Material: Is marine plywood necessary?
Niven Paine -- 1/10/2011, 4:00 am
Re: Material:BS1088 Means Certain Things.
Charlie -- 1/11/2011, 11:27 am
Re: Material: Is marine plywood necessary?
Eric -- 1/10/2011, 10:56 am
Re: Material: Is marine plywood necessary?
Bill Hamm -- 1/10/2011, 12:29 pm
Have to agree
Kudzu / Jeff Horton -- 1/10/2011, 3:06 pm
Re: Material: Is marine plywood necessary?
Dave Houser -- 1/10/2011, 3:35 pm
Re: Material: Is marine plywood necessary?
ancient kayaker -- 1/10/2011, 7:06 pm
Re: Material: Is marine plywood necessary?
Paul G. Jacobson -- 1/11/2011, 8:58 am
Re: Material: Is marine plywood necessary?
Charlie -- 1/11/2011, 1:00 pm
Re: Material: Is marine plywood necessary?
Mike Savage -- 1/11/2011, 7:47 pm
Re: Material: Is marine plywood necessary?
Bill Hamm -- 1/12/2011, 1:00 am
Re: Material: Is marine plywood necessary?
ancient kayaker -- 1/12/2011, 1:34 am
Re: Material: Is marine plywood necessary?
Bill Hamm -- 1/12/2011, 2:47 am
Re: Material: Is marine plywood necessary?
Paul G. Jacobson -- 1/12/2011, 3:06 am
Re: Material: Is marine plywood necessary?
Niven Paine -- 1/11/2011, 3:24 pm
Re: Material: Is marine plywood necessary?
Tyler Dunn -- 1/15/2011, 2:31 pm
Save time on your Sea Fleas
Paul G. Jacobson -- 1/15/2011, 3:39 pm
Re: Material: Is marine plywood necessary?
ancient kayaker -- 1/15/2011, 4:24 pm
Re: Material: Is marine plywood necessary?
Bill -- 1/14/2011, 5:36 pm
Re: Material: Is marine plywood necessary?
Bill Hamm -- 1/14/2011, 7:27 pm