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Marine grade plywood

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Marine grade plywood
I'm replacing the transom in my 19' starcraft. Does anybody know where to get marine grade plywood in NJ?
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Re: Marine grade plywood In reply to
A boat transom doesn't need marine ply. A good AB ply will work fine.
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Re: Marine grade plywood In reply to
I?ve had good luck with South jersey lumbermans in mays landing. Doesn?t look like much but Steve can get you anything you want.
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Re: Marine grade plywood In reply to
Best price i found was nacote creek marina on rt 9 in Leeds Point
South Jersey
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Re: Marine grade plywood In reply to
I used Okoume Mahogany plywood, when I replaced the transom wood in the boat I had at the time. I laminated three layers of 18mm to get the desired thickness for my transom. This was thicker than original and that was my plan. (the original was only 1.5 inches thick)

Take care, Huntindave McCann Smile SHELL ROCK IA “As sailors grow older, the wiser ones move to smaller boats.” —Thomas Firth Jones, Multihull Voyaging
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Re: Marine grade plywood In reply to
 Joe, I would go with marine grade. Don't like to do it twice. One of our better boat manufacturers on long island made commercial boats and now nice fishing boats ran in to problems in the transoms using cheaper plywoods. Many were still in warrantee. Now using marine grade materials now. JMO
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Re: Marine grade plywood In reply to
Maybe somebody could clarify this for me about marine grade ply. My understaning is that virtually all plywood is exterior except for some of the real cheap underlament so the glue will not deteriorate if the gets wet. But the major difference, hence the higher cost of marine, is that there are no voids in the internal layers so there are no weak spots or pockets that can collect moisture.

That said, I have used regular AB ply from home depot on boats in the past to keep costs down. I just got 4 sheets to build a PD Racer sailboat with my son and the goal is to do it for as cheap as possible. When I built my duckboat I used okume marine becasue I wanted it to last and it is almost 15 years old with no issues and its stored outside.
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Re: Marine grade plywood In reply to
Marine Grade, varies, and within marine grade, some are better than others.

Typically, marine grade will have a better quality adhesive used, has no voids, more ply for a given thickness (more glue), and all the ply will be a quality wood. Construction grade plywood may have a waterproof glue, but the core plys will be lesser quality, have voids and be a larger percentage of the thickness.

Dave Diefenderfer
Manassas, VA

"Once you set out to build a boat, throw away your square. And if you work on her after she's launched, throw away your level." author unknown

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Re: Marine grade plywood In reply to
Neal Haarberg wrote:


That said, I have used regular AB ply from home depot on boats in the past to keep costs down. I just got 4 sheets to build a PD Racer sailboat .


Can you provide a stock number for the product you purchased? I could not find "regular AB ply from home depot" listed so It is hard to verify the specifications for this product.

Neal Haarberg wrote:
,,,,,,,,,My understanding is that virtually all plywood is exterior,,,,,,,,,,


Okokume usually has more layers per inch thickness, thus is stronger as well as the attributes you listed. I find that the quality of the wood in those layers is also a higher quality and more consistent in grain structure as compared to the Fir Marine Plywood.

Actually no. My guess is more interior grade plywood is sold than exterior grade. All plywood (that I'm aware of) sold as "sheathing" is listed as interior grade. "Birch plywood" (more layers, even thickness, real flat and consistent) and "hardwood plywood" is usually intended for cabinets and other interior projects. Even just the "regular" sanded plywood listed below is rated "interior" even though the description says "Sanded project panels are perfect for interior and exterior applications".

15/32 in. x 4 ft. x 8 ft. BC Sanded Pine Plywood
  • Each piece of this lumber meets the highest quality grading standards for strength and appearance
  • Sanded project panels are perfect for interior and exterior applications
  • Great for yard art to wainscoting, do-it-yourself projects, cabinets, shelving and furniture to porch ceilings, soffits and flooring underlayment
  • Excellent appearance when painted

  • Weather Exposure ----- Interior




Take care, Huntindave McCann Smile SHELL ROCK IA “As sailors grow older, the wiser ones move to smaller boats.” —Thomas Firth Jones, Multihull Voyaging
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Re: Marine grade plywood In reply to
Dave,
I cannot get a part number for you. Over the past 20 years or so I have used multiple grades of plywood for 5 boats. 1 was simply decking not actually building the boat hull.

Thank you for clearing that up for me on the interior plywood. I have been told by a couple people that the most plywood manufactures don't want to change adhesives for interior or exterior since adhesive technology has come a long way in the past couple decades and the cost savings are not there due to change over costs.

Also I live in the Pacific Northwest where we cut down a lot of doug fir trees for veneers and the bulk of what you find here is fir not pine unless it is going to be for cabinetry then who knows where it comes from. Not here, we don't have squat for hardwoods.

Not to detract from plywood, but maybe you can clear something else up for me that I have heard and am curious about. Is most of the lumber, 2x whatever, dried in most lumberyards in Ohio. Here unless it is a 8' 2x4 or 2x6 most is green because the mills are close enough that drying the wood only becomes cost effective once it has to transported far enough because of the weight savings. Don't know if it's true, but it's what I told by a guy who sold lumber about 10 years ago.
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Re: Marine grade plywood In reply to
Neal Haarberg wrote:

Not to detract from plywood, but maybe you can clear something else up for me that I have heard and am curious about. Is most of the lumber, 2x whatever, dried in most lumberyards in Ohio. Here unless it is a 8' 2x4 or 2x6 most is green because the mills are close enough that drying the wood only becomes cost effective once it has to transported far enough because of the weight savings. Don't know if it's true, but it's what I told by a guy who sold lumber about 10 years ago.


Well, I'm not really in the lumber business (just had done a lot of previous research concerning plywood) so I did a bit of quick research. Seems that some markets see green wood and some markets see kiln dried. Pluses and minuses when working with either product. Personally I'd prefer to work with kiln dried because I'm anal about attaining perfect or near perfect dimensions in my finished product. (38 years in a tool and die shop).

There are some markets in which the primary lumber for all purposes is green ? Oregon west of the Cascades, most of California, parts of Arizona and New Jersey. With the issues of shrinkage of green lumber, one would think dry lumber would be used everywhere ? but it is an economic decision in which pocketing greater profits outweighs the quality of the finished product.

Take care, Huntindave McCann Smile SHELL ROCK IA “As sailors grow older, the wiser ones move to smaller boats.” —Thomas Firth Jones, Multihull Voyaging
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Re: Marine grade plywood In reply to
I will add that the marine plywood (BS1088 et al) do not have interior voids, and of species that are not as susceptible to rot. For the price, why not do it right?

---------------------------------------------------------------------
***Phil (Chesapeake Boy) Nowack***

http://www.mapleridgetaxidermy.com
http://www.philnowackphotography.com

Nothing like the north wind pushing snow at your back, a bird in your hand, and chessie with ice on his coat at your side.

Birds brought to you courtesy of Nikon, Benelli, Kodi, and Otter
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Re: Marine grade plywood In reply to
Until Joe states his plans for how he will construct the transom I'll stick with my original suggestion. He mentioned it was a StarCraft and I assume it is one of their aluminum boats. Most of the wood transoms I've seen in aluminum boats are bare wood with numerous holes bored through them, e.g., drain, handles, depth finder pickup, etc.. Typically they are poorly sealed with maybe a coat of paint but mostly live bare under a skin of aluminum. In other words they are essentially exposed wood. Marine Okoume is very prone to rot and if not completely sealed would be a TERRIBLE choice. Meranti is also a common marine ply species and slightly better than pine in terms of rot resistance, but in the typical aluminum boat transom repair wouldn't offer much more than pine. Those transoms fail because people bore holes and don't seal the exposed wood. We aren't talking about a epoxy encapsulated hull where the integrity depends on the quality of materials and workmanship. We are talking about a disposable part that will be replaced anyway due to typical application and construction. Marine ply isn't needed, a nice AB domestic ply will be fine in this application. For me availability/cost would be the driver and I'd easily go for something I could pick up no hassle from a local supplier.

Edit: Avoid treated plywood as it will corrode the aluminum. At the very least research the treatment and determine if it will corrode aluminum. They are using different treatments these days, some do, some don't.

Last edited by:

Eric Patterson: Jul 11, 2019, 8:27 AM
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Re: Marine grade plywood In reply to
I would use Meranti, epoxy it together, and epoxy all exposed surfaces.

This is purely antidotal, but I have some scraps of Meranti (Hydrotech) outside on a pile of scrap wood... from the Honker build in 2006.. not delaminating and not rotten.... ish .

---------------------------------------------------------------------
***Phil (Chesapeake Boy) Nowack***

http://www.mapleridgetaxidermy.com
http://www.philnowackphotography.com

Nothing like the north wind pushing snow at your back, a bird in your hand, and chessie with ice on his coat at your side.

Birds brought to you courtesy of Nikon, Benelli, Kodi, and Otter
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Re: Marine grade plywood In reply to
All I can speak to is my personal experience when I replaced the wood in the transom of my 1974 StarCraft Super Sport runabout. I used the Okoume marine plywood because I felt it had superior structural strength for a given thickness as compared to other available products. The sheet was rough cut and the three cut pieces were laminated together with epoxy to form a rough cut blank just a shade over 2 inches thick. This was an increase over the 1.5 inch original thickness.

The blank was then fitted to final size and several areas were cut back to original thickness using a router. this was done for the supports and other items, which could not accommodate the increase in transom thickness. At this time the blank was set into position and all thru holes were drilled in location.

The blank was then removed, cleaned up, and sealed with epoxy. After two coats of epoxy, the blank was given a couple coats of white paint to lighten to bilge area and protect the epoxy.

Was using Okoume the best choice, I don't know. All I know is this is what I used. I apologize if I mislead anyone by failing to go into detail in my original response.














Take care, Huntindave McCann Smile SHELL ROCK IA “As sailors grow older, the wiser ones move to smaller boats.” —Thomas Firth Jones, Multihull Voyaging

Last edited by:

Huntindave McCann: Jul 11, 2019, 10:06 AM
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Re: Marine grade plywood In reply to
If you go to nacote creek he has hydrotek and 1/2 inch is about 100 bucks a sheet when I went to see Pincus at south Jersey Lumbermans and he had to order it a few months back. If you find a way to vacuum bag exterior grade Fir would that solve the internal void rot concerns? I just replace a little boats transom with Exterior grade Fir with the value of the boat I didn't think twice.
South Jersey
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Re: Marine grade plywood In reply to
Dave

Your transom rebuild was done to a much higher standard than any I've seen. We don't know what approach Joe intends to take with his repair so it is hard to say what plywood should be used. My thoughts, based on how folks usually repair aluminum boat transoms, is AB exterior. If he is epoxy coating and sealing to the length you did in an effort to make it last forever then higher quality materials are warranted. If he simply wants to put it back like it once was then domestic ply is called for, IMHO. Keep in mind there are a lot of people who think marine ply is "waterproof" and simply by the virtue of using it they have protected themselves from future problems. You and I both know it isn't that simple.

Eric

Last edited by:

Eric Patterson: Jul 11, 2019, 10:55 AM
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Re: Marine grade plywood In reply to
Thanks guys. The reason it is being replaced is the manufacturer originally used pressure treated wich is now causing pinholes in the aluminum. Original thickness is 1.5" wich I will not be able to build up. I had planned to epoxy with cabosil two 3/4" layers of marine grade together . Then seal with epoxy. Also I will be using a product called muggy weld (low temp brazing)to fill all holes.