TOPIC: Plywood choice..

Hello again everyone, I have some fiberglass/resin ect on the way here this week so I'm making the final choice on materials for my transom repair. Was looking at menards today and they have the MDO ply for like 40 bucks a sheet but then what really caught my eye was the baltic birch ply for 55 bucks a sheet (1/2" 9 plys). It says it is for interior or exterior so I'm thinking that means it has the right glue. Both of these panels are WAY WAY flatter and true than any of the regular exterior grade plys they have there so its between the two.. I am leaning toward the birch. Was wondering what people think of that for a transom.. seems to me it would be better with all those layers and the fact that its the same material all the way thru, rather than wood core's with the mdf material on the outer skins..

Thanks for any info..

It is a Nice FLAT plywood but in my opinion not suitable for a boat. The exterior grade does use exterior grade glue but it is NOT 100% waterproof and therefore inferior to the others. MDO and Ext. Grade FIR plywood DOES use 100% waterproof glue in their products. Hope this helps.

Ah thanks flamingo thats good advice, was hoping someone had an opinion on that.. also saves me 15 bucks.. right now I'm building a shelter so I can do this work out of the weather and then I'll be buying a sheet of MDO and cranking out that transom.. then onto floor/stringers. It will be nice to get those major repairs out of the way so I can fool with the more cosmetic stuff.. I would like to get the boat finished this summer so that I can think about motor/control's/steering for next spring.
Thanks again for the info..

I researched the crap out of Plywood before I bought stuff for my Delmar ..Best deal I found is some ply called Arauco Ply . Its sold at Menards , Lowes and Home Depot ..Its very reasonable .What your looking for is Exterial Grade glue and for lack of voids in the wood .Some plys are glued 1/2 Arsed ..I read up on this stuff and it sounded good .Its a 1/3 of the price of Marine Grade .I bought a sheet to build interior pieces for the Delmar and experiment with it .When cutting it I found NO Voids in the glue Looked perfect where ever you cut .Both faces are nice and finished .I took a piece and boiled it in water for a long time repeatedly over a few days . I let it set a week and boiled it again .It never showed any sign of glue failure and still hasnt after 4 months I tested it .I even put it out in 10 below zero weather for a day after I boiled it . It was water saturated but the glue held even when frozen solid .I stress tested a piece and bent it way farther than you ever would . It held up fine even after being wet . No glue failure ..SO ...Im building my transom out of it .Im gonna seal it good with Epoxy because epoxy soaks in and seals it . Poly Doesnt ..Then Ill cover it good with biaxial cloth .Is Marine Grade Ply water and Rot Proof ?? Ask any good lumber man and he will tell you Heck No ..Im Convinced that If I seal it good this transom will out last me ..And no I dont sell this stuff ..Just shareing my personal testing and research with ya ...But I did stay at a Holiday Inn Last Night ...L.O.L..

Arauco Ply is an EXCELLENT choice for boat restoration. I should have made mention of it. Thanks for chiming in BoBo.

It really is nice ply .I got 3 sheets of 1/2 up here for under $70 . For Marine Grade up here they wanted around $85 for 1 sheet of half .If you go on my Operation Delmar Stage 2 thread you can see some of it ..Looks like Marine to me . I think the biggest difference is $60 a sheet ..L.O.L..

Good thread, and right on time for me! (Hope to be ready to start on putting a floor in the GT 150 in another week or so.) Thanks for the tip on Arauco ply Larry, I'll look for it here in Atlanta!

While were on the subject, is 1/2" sufficient for flooring, or would 5/8" be the better choice?

Mark,
If it were me I'd go with 5/8" but I have a tendancy to over build things. I think the floor in my boat is 1/2" and seems a little bouncy in spots but it's the original floor and over 50 years old.

Bob

Thanks Bob, that's kinda the way I'm leaning as well. Better over built than under built, right?!

I think the stringer configuration has a lot to do with your deck thickness selection. If the span between the stringers is more than 16" then I would recommend 5/8" If 16" or less then 1/2" should be fine and it would save you about #40 in weight. Also if you will be putting in pour in expanding foam then 1/2" is more than sufficient since the foam will add additional support to the bottom of the ply.