Transom Wood - If you had your choice

[rscottp]

tonynoriega » 06 Feb 2014, 18:15[/url]"]If I did a marine plywood, sammich two 1/2" pieces together...can I put a nice stain on it?

Was looking at this nice dark red stain at the REstore the other day... I think it was exterior grade.

Then put a few coats of spar urethane over that?

Or Epoxy over the stain?

Stain away! You may want to stain before you sammich since the stain will not take to the glue line.

 

[T Man]

huntinfool » Yesterday, 15:09[/url]"]

The correct answer is; marine plywood sealed with epoxy. Call around you can find it at a lumber yard near you. Here in California, it runs about $75 a sheet.

you for realize the only difference in "marine" ply and regular ply is there are no voids in the plys. Marine ply is also considered cabinet grade.

I believe it is made with a waterproof glue unlike cabinet grade ply.

muskiemike12 » 05 Feb 2014, 12:18[/url]"]Seeing that this is a 40 year old Alumacraft that takes a portable motor, that clamps on, aluminum would not be wise to use. If you are bolting the motor on then go for it. The hand tight clamps will have nothing to bite into and you motor will go overboard!

Thats ridiculous. A a clamp wont compress the wood anymore than 1/8th of an inch unless it is rotten and even clamp on motors should be bolted onto a transom. Ask me how I know.

 

[SumDumGuy]

How do you know that clamp on motors should be bolted to the transom?

 

[T Man]

SumDumGuy » 18 minutes ago[/url]"]How do you know that clamp on motors should be bolted to the transom?

Mine fell off while making a turn. Clamps were tight enough one of the handles had broken. The cables for the controls and the fuel line were all that kept it from sinking. I managed to get it shut off while it was still running, although underwater. (Just enough air under the cowl) Pulled it up, dried it out and it runs like a champ. Most definitely bolted on now though.

 

[huntinfool]

I believe it is made with a waterproof glue unlike cabinet grade ply.

Wrong.

Here is some info I copied from a site from Australia. It is no different than here in the U.S.

 MARINE PLYWOOD EXPLAINED

   

Many Australians grow up with the belief that Marine Plywood is a ‘special’ product made with secret adhesives that make it virtually indestructible. This is an urban myth.

The adhesive (glue) that is used to bond the veneers of Marine Plywood together is the same as any other structural plywood that is manufactured in Australia.

What is Marine Plywood and why is it so expensive?

A boat travelling through water is subject to plate action from waves and floating debris. Marine Plywood is designed to absorb these forces due to the fact that this plywood is the closest to solid wood. In fact it is better than solid wood with defects having been graded out.

Marine plywood is manufactured using the highest quality grade of veneers.  These veneers don’t have defects and thereby eliminate core gaps when the sheet is cut. These veneers are not available in volume compared to lower grades.

As these high grade veneers are used in every layer, marine plywood is dearer than other grades such as structural plywood




As I said there are no gaps in the wood. All perfect veneers that are glued together, making them very expensive. Same reason cdx is cheaper than ab plywood. More gaps in cdx.

I have probably made well over 100 transoms in my lifetime. I started in '88. Since I did this for a living for almost 20 years, I'm not just giving opinion. Now days we don't make them out of wood. We pour solid glass transoms.

I posted a thread here several years ago about it.

Anyways, I'm not trying to come across as a know it all. I am trying to be helpful and informative to everyone here. Since this is the inter web and no one knows how I am saying this, I just want y'all to know. This is just informational.

 

[WVfishnfool]

I'm using the same type board that they use for flooring on flatbed and enclosed trailers that you see on the highway every day. This is a laminate oak(usually white and red) that is bonded with some of the strongest adhesives out there. Plus the thickness was exactly the same as the transom board that came out. This stuff is punished every day either hauling 40-50,000 lb. loads for hundreds of miles in all types of weather to having 8-12,000 lb. forklifts flying in and out of trailers loading and unloading and have no special sealants or anything else on them and on average the floor will last at least 7-10 years with just spot replacement some time. And like I said that is without any sealants to protect it. I've made one for my 14 foot john and have it installed already. I coated it with epoxy resin and fiberglass cloth so it should outlast me and the boat. As far as a board for the outside of the boat I'm going to use a heavy plastic cutting board instead of wood. This should give a cushion to the aluminum plus absorb any vibrations from the outboard.

 

[nlester]

I think you will find this interesting.
"Purpleheart stands on its own in the wood species. Purpleheart is an extremely dense and water resistant wood. It is ranked one of the hardest and most stiff of the woods in the world. Some people claim it is so durable that people use it as truck decking."
I don't know how badly it warps but if it is sealed properly it should be okay. You will need to use a sealer with a UV rating or it will turn a chocolate brown with age.

I like almost any solid wood the best as long as it's sealed, with teak being high on the list. It is easy to get varying dimensions out of solid wood on the table saw. Next marine plywood because it is manufactured without voids, the best quality of glue and interior laminations.

I used white pine lumber, covered in fiber glass and sealed with resin. I don't know if this will last but after 2 years, it is still almost like new. I used several strips, reversing the grain on every other piece and glued together to make up each piece. It's the way we use to build table tops.

 

[kfa4303]

Great point on the marine plywood and securing the motor from posters above. My motor has two large safety chains on it to keep it from going down to Davey Jones' locker. It's cheap insurance. There's really nothing "special" about marine plywood either, aside from the fact that it has few if any voids. It sure does cost more though :/ You'll have to decide if it's worth the extra money. Also, while dimensional lumber looks great, and is fine for project this small, laminated transoms are actually stronger and will likely last longer and be less expensive to assemble in the long run. However, if you're going for looks Cypress, Oak, Teak and others would be nice, if not terribly affordable.