marine ply vs. regular ply transom

[tburris]

Ive got just a couple more forms to make and then its time to set up. Im building the Allegra 24, using strip planking and cold molded. I plan on stripping with Port Orford then laying 2 1/8inch layers of (not sure yet) veneer. The question I have for you is that the plans call for using plywood for the transom, should I use marine ply or is regular ok? I want to finish the outside of the transom natural wood so I will be using the veneer on it also. I guess my main concern is strenght, is plywood adequate? Soon as I get the forms set up I will post pics for you all to critique.

[Bob Smalser]

Longevity, not strength, is the issue.

On a project of that size and cost, I wouldn't even consider anything but the best Doug Fir marine ply I could get my hands on from a reputable boat wood supplier like Edensaw or Flounder Bay.

What I dislike about plywood is not being able to see inside...voids...glue...sapwood...all potential trouble spots I'd put my money up against ahead of time by name brands from known suppliers.

I might take informed risks and shortcuts on smaller projects...but I certainly wouldn't on your significant investment in this vessel.

I'd also "double drill" all the holes I put in that plywood, too...just like in glass boats....drill oversize, fill with thickened epoxy, and drill again to spec.

[ 07-18-2004, 08:27 PM: Message edited by: Bob Smalser ]

[Domesticated_Mr. Know It All]

You want plywood with no voids between the layers.
Douglas Fir Marine grade.
BS1088

www.homesteadhardwoods.com (http://www.homesteadhardwoods.com)

[htom]

Best quality marine ply.

[WindHawk]

Is there a reason why a solid transom would not be considered?

[Venchka]

Is there a reason why you couldn't make your own transom? Using the same Port Orford cedar strips and veneer glued up to the same thickness as the marine plywood specified? Just guessing: 1/2" strips and 3 layers of 1/4" veneer inside and out yields a 2" transom. Another possibility: a transom frame of 1"x3 1/2" P.O. cedar and 3 layers of 1/4" W.R.C. on the outside.

If Flounder Bay Lumber still have Shelmarine sapeli (spelling?) plywood that's about as good as it gets.

Wayne

[tburris]

I thought about a solid transom, but thought that a plywood built up with layers of veneer would be as strong? My intentions were not to save money but only the thought that I have the standard ply available were as I have to go and purchase the marine grade. Which is fine, I do not want to skimp or take any short cuts. Thanks for your replies.

Ted

[imported_Conrad]

If fir, you might check some of the MDO sign ply- I have several sheets at home that are superior to the last batch of "marine" fir I purchased, and about half the cost. No visible side voids, all fir, (No hemlock, etc. inner plys) and exterior glue with a nice resin finish on both sides. Might be worth a look and more likely to be available locally.

[Bob Smalser]

Go to Simpson or Weyerhauser sometime and watch'em make plywood if you have the chance.

The veneers for plywood are rotary cut on a big lathe from plantation-grown, pruned, DF "peelers" in the 24-inch. 4-6 rings/inch range.

Of a 24" peeler-grade (straight) log, the first 3-4" of that log is quick-rotting sapwood...

...they don't throw that sapwood away, folks. It goes into any and all interior-grade stock.

Voids and glue ain't the only issues. It may look and work great...but you still can't see inside...."marine" ply means more than just glue.