Coosa vs Ply for transom?

[Marcel4t]

71 FB that I am going to close transom in on.  I've been reading and reading on builds, and a lot of you guys are using Coosa for transoms, but others are going old school with ply.   Now, I know some of you guys have money to burn, and I am not going into this with the expectation that my build is going to be cheep, but if I am doing the math, Coosa is WAY more expensive than Ply, like $600+ for 2 sheets of 3/4 Coosa vs $140 for 2 sheets of ply.  Am I right on that? Coosa has amazing benefits over Ply, yes, but I'm hesitant to go that route vs ply, which has been successfully for decades.  Yet I'm feeling compelled to go with Coosa out of fear I would regret it one day and it seems like this is the popular way to go.   

[RickK]

I went with 2 layers of marine plywood (Lowes @ $80 per).  See my rebuild for how I did it.

[Woodeneye]

Coosa has benefits in that it is not as susceptible to water ingress as ply and as such will last a looooong time.. Ply is great as long as water doesn't get into it. Without knowing how long you plan to keep the boat, if it is in the water for long periods, how many holes you plan on drilling through it...etc..etc...it's hard to say. There are definite dollar benefits to ply. But if you still have the boat in 30 years (??) and you have to do the transom again you will be looking for a dog to kick.

Then again......... if you pay pedantic attention to sealing any hole you put in the transom it will be just fine. My transom is over 35 years old and (knock on plywood) is just fine.

I should not have said that ...let alone even thought it....

[theFunsmith]

I do not have money to burn, but I decided on Coosa because I plan on keeping the boat for life and I never want to do this work again. I pulled out so much rotten wood in my deconstruction, that I am totally turned off to it anywhere in the hull where water will be regularly. The price difference when compared the whole cost of the boat rebuild was not so hard to swallow.

[Fish Head]

I used 3 layers of 1/2 inch marine ply from Menards. $50 a sheet and they also give 11% back to spend in store on other stuff. I went with 3 layers because the thinner layers conformed better to the small curve of my 19’6 transom.They bend easier.  Only holes in my transom will be the 4 motor mounts. Those I will drill oversized and reseal with premixed gflex from West System. Then re- drill holes so I will have no exposed wood. I plan on building up a small pad at least a inch thick of 1708 at the bottom for the transducer. Again no exposed wood. Like you said, not interested replacing the transom again. Screwing stuff into the transom wood and sealing with 3M whatever does not seem to be a lasting technique IMHO. Cheers T

[Marcel4t]

Thank you all for input.  One consideration was that using Coosa and composites will have a better resale value. At least that I think so.  So, I'll go with Coosa for transom and figure out what to use for stringers and floor. 

[RickK]

There are plenty of examples of stringers in the rebuild forum.  Some made them from composite board and some from fiberglass.