First Boat: What in the name of all that is holy ?

[Iamnu2boats]

Total novice here but I bought a 14' aluminum boat, perfect in all respects but one: The transom. Removed the non stainless fasteners to see what I had to work with.

OMG: Plywood turned to parchment paper.

Anyway, was able to salvage one piece of the wood to use as a pattern. Thank you iboats, as I read a bunch of info on replacing these transoms but it appears the standard is two pieces of plywood, marine grade (?), glued together, covered in either fiberglass or epoxy, and put back into place.

I am wondering, however, after measuring the "pattern board", why I can't use something like an inorganic decking material (Trux, etc) of the same size, on the inside of the transom and a similar material, size appropriate, on the outside. Some reason to NOT use a poly based product?

Looking for experience and help here.

 

[Isaacm1986]

Re: First Boat: What in the name of all that is holy ?

My experience with trex decking is it is not very strong. I have a deck built with it, and the boards still have a slight flex to them with joist every 16". I would not use it in a transom at all.

If you are looking to save money, just use exterior grade plywood, sealed with epoxy resin. That will last 20+ years.

Good luck on the transom replacement.

 

[NoKlu]

Re: First Boat: What in the name of all that is holy ?

Make sure the ply is good and dry before you seal it up.

 

[mnmike3]

Re: First Boat: What in the name of all that is holy ?

Trex decking is NOT structural at all. I have built a few decks using it and it is great decking but I wouldn't use it for a transom. I can pick up a 16ft trex decking board over my head in the middle and both ends will still touch the ground. I would go with the exterior grade plywood coated in epoxy resin or marine plywood

 

[lckstckn2smknbrls]

Re: First Boat: What in the name of all that is holy ?

Just don't use pressure treated wood. It will cause pitting of the aluminum hull.

 

[Iamnu2boats]

Re: First Boat: What in the name of all that is holy ?

Thanks for all the great comments. I find it interesting that the marine grade or exterior grade plywood is the wood of choice.

Is there a particular resin to use to seal the wood? I have also read that several layers of wood are best. I presume this is to maximize the rigidity of several over one?

Thanks again.

 

[petermarcus]

Re: First Boat: What in the name of all that is holy ?

You can use a poly resin, or an epoxy, and uscomposites.com is a forum favorite for a good ball-park when it comes to supplies.

A lot of transoms, especially for I/O's, have to be a certain thickness, and it's easier to mate two 3/4" plywood pieces together, than it is for the plywood mill to make a 10-12 ply 1.5" plywood thickness in 4x8' pieces and find a market, deal with shipping, the weight, etc. Plus, yeah, there's a structural consideration when epoxying them together with some glass in between. All in all, if you coat it right and take your time with the details, it'll last longer than the boat builder's original attempt.

 

[hotrod53]

Re: First Boat: What in the name of all that is holy ?

I just made a new transom for my '78 Sylvan Sea Master project and went thru the same thing, I had to hammer and chizel mine out, at least that which wasn't mush..here's my advice:

1. Exterior wood is unstable and warps like nobodys buisness before you get it in. Marine stayed straight as an arrow, has more plys, and is stronger. IMO, well worth $75 a sheet for 3/4" for this application.

2. Stear clear of the poly resin, poly resin is not nearly as good as Epoxy resin, check Ebay, I got $20 worth and glued the transom, coated the transom, and had some left over. Here is what I used and it was the bomb, Max Bond brand for boat building, low viscosity:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=280255931847&ssPageName=STRK:MEWNX:IT

I used the epoxy straight to glue the 2 plys and cut the mix with 10% Acetone for sealing the rest. Poly resin STINKS BAD and working time is 15 minutes. Epoxy resin has a milder smell and working time was probably 45 minutes.

3. I used poly resin and ACX for the new floor. In retrospect I would still have used ACX but would have coated it with epoxy.

 

[slogen]

Re: First Boat: What in the name of all that is holy ?

Total novice here but I bought a 14' aluminum boat, perfect in all respects but one: The transom. Removed the non stainless fasteners to see what I had to work with.

OMG: Plywood turned to parchment paper.

Anyway, was able to salvage one piece of the wood to use as a pattern. Thank you iboats, as I read a bunch of info on replacing these transoms but it appears the standard is two pieces of plywood, marine grade (?), glued together, covered in either fiberglass or epoxy, and put back into place.

I am wondering, however, after measuring the "pattern board", why I can't use something like an inorganic decking material (Trux, etc) of the same size, on the inside of the transom and a similar material, size appropriate, on the outside. Some reason to NOT use a poly based product?

Looking for experience and help here.

i just re did my transom i went fiber glass then plywood fiberglass plywood then screws wvry 4" squared then fiberglass a few more times it came out super strong

 

[jonesg]

Re: First Boat: What in the name of all that is holy ?

I just made a new transom for my '78 Sylvan Sea Master project and went thru the same thing, I had to hammer and chizel mine out, at least that which wasn't mush..here's my advice:

1. Exterior wood is unstable and warps like nobodys buisness before you get it in. Marine stayed straight as an arrow, has more plys, and is stronger. IMO, well worth $75 a sheet for 3/4" for this application.

2. Stear clear of the poly resin, poly resin is not nearly as good as Epoxy resin, check Ebay, I got $20 worth and glued the transom, coated the transom, and had some left over. Here is what I used and it was the bomb, Max Bond brand for boat building, low viscosity:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=280255931847&ssPageName=STRK:MEWNX:IT

I used the epoxy straight to glue the 2 plys and cut the mix with 10% Acetone for sealing the rest. Poly resin STINKS BAD and working time is 15 minutes. Epoxy resin has a milder smell and working time was probably 45 minutes.

3. I used poly resin and ACX for the new floor. In retrospect I would still have used ACX but would have coated it with epoxy.

Looks like a homemade re-label of enviro-tex epoxy , get it at ace hardware stores, good stuff.