Glass plywood for transom on Aluminum boat?

[itiger]

Hi all,

I am working on a project to replace the transom on my 82' Bass Tracker. I plan to glue two sheets of 5/8" plywood to fit the original thickness of 1-1/4" and then apply epoxy on the sides and edges to make it waterproof.

Now I got questions:
1. What glue or resin should I use to glue two sheets together?

2. What epoxy should I use for the outside of the board? I did some research online and people talk about "epoxy". But what exact epoxy are they referring to and where to get it?

3. Do I need to use fiberglass cloth/mat to strengthen the transom? If so, where to apply it?

4. Is pressure treated plywood necessary, considering the board will be epoxy-ed?

Thanks for your patient.

 

[jigngrub]

Re: Glass plywood for transom on Aluminum boat?

1. Tightbond III glue

2. A lot of people here use the 635 resin with the medium 3:1 hardener from here:
http://www.uscomposites.com/epoxy.html

3. You only need to use glass cloth/matt when using polyester resin instead of epoxy, epoxy will work fine by itself.

4. Pressure treated wood in an aluminum boat is a no-no, it will corrode your aluminum.

 

[kfa4303]

Re: Glass plywood for transom on Aluminum boat?

+1. Tightbond III is great, you can also use the epoxy itself to "glue" the two layers together, but the titebond is cheaper, easier to get a hold of and will have a little longer work time. The epoxy is great stuff to seal the transom (or any wooden components with), but it is a little pricey and has a limited work life, so once you make a batch you gotta move pretty quick. If you do go the epoxy route, no need for fiberglass. However, once it's sealed you will need to give it some UV protection in the form of paint. However, if you can't get the epoxy, or the cost is prohibitive, you can use SPAR URETHANE instead. It's available at any lowes/HD, works quite well, does not require an additional top coat like the epoxy and is much cheaper. If do you choose to go the spar urethane route, you'll be able to get virtually everything you need for an entire aluminum boat rebuild from the big box stores. They carry the non-PT exterior grade plywood you'll need for the transom and decking, the Stainless Steel hardware you'll need to use to install it all, as well as the 3M 5200 sealant which should be used on all through-hull fittings just prior to their installation. They also carry and all the various paints and primers for the hull. They even carry aluminum stock and angle from which you can fabricate any braces you might need. Epoxy is great, but it may not be worth the extra time and expense. Keep us posted....

 

[itiger]

Re: Glass plywood for transom on Aluminum boat?

So it's okay if I use the BC sanded pine plywood?

Sounds like the SPAR URETHANE is a perfect choice. I search the HD and found the "Minwax Helmsman 1 qt. Satin Spar Urethane". Is this the right product?

Thanks again.

 

[ondarvr]

Re: Glass plywood for transom on Aluminum boat?

Try for fir plywood instead of pine.

 

[CoffeeHound]

Re: Glass plywood for transom on Aluminum boat?

Sounds like your on the right track !!
Be sure to paint both sides and all edges with 1 to 3 coats of Spar ,,specially the edges . I used CDX 3/4 ply with C side up then sanded one time . Made for a great looking deck. Transome will be done this winter when i set-up for the second motor on my tinny.
Neptune will smile on you for NOT using PT of any sort in your boat or on your trailer !!!

 

[kfa4303]

Re: Glass plywood for transom on Aluminum boat?

That's the stuff. Here's a pic of a different brand, if that helps. The plywood sounds fine too, just make sure it's exterior grade and NON-PRESSURE TREATED. Most folks end up using two layers of 3/4". There is a brand called Aruaco that is very popular. Try to take the old transom out in one piece to use as a template. Once you've got the new one cut, pre-drill all the holes for the new stainless steel mounting hardware, then give if 3-4 coats of spar urethane. After it cures, mount it to the transom using the SS hardware apply some 3M 5200 marine sealant to them, like putting mustard on a hot dog, then install. You should notice the 5200 oozing out from all sides, which is what you want. Wipe of the excess with a bit of acetone and let cure fully. You should be left with a transom that will outlive you.

 

[itiger]

Re: Glass plywood for transom on Aluminum boat?

Thanks for all your advices. I will get some pictures and keep you posted.

 

[Yacht Dr.]

Re: Glass plywood for transom on Aluminum boat?

Are you so sure that sealing up your Transom wood with Minwax Varnish is a good Idea ?

I would coat the wood with poly .. slurry some poly ( or epoxy if you really want it tanked ) cabosil mix and screw the 2 plys together..( BC ply is not the best for using water based one application Glue in and of itself ).

Prep it and re coat the transom again with as much poly( or epoxy) as it takes for your " BC " PLY to stop drinking the resin. Then re prep again and put your topcoat on if thats what your going to want for your finish.

YD.

 

[kfa4303]

Re: Glass plywood for transom on Aluminum boat?

Sure, for the cost and convenience it can't be beat. The materials you mentioned are great if you have the time, money and experience to deal with them, but they're probably overkill for a small tin boat and a one off application. You can get a gallon of Spar Urethane from any big box store for $30 and it will be more than enough to give several coats to all of the wood in the boat and Titebond III is also readily available and affordable at the same stores. To get a gallon of 2 part epoxy and cabosil, etc...shipped outside of FL from someone like US composites would probably cost about as much as the boat.

 

[itiger]

Re: Glass plywood for transom on Aluminum boat?

Okay I have cut the board and applied the Tightbond. Here are a few pictures:

Old transom:


Newly Cut:


Glue Together:

 

[Yacht Dr.]

Re: Glass plywood for transom on Aluminum boat?

Sure, for the cost and convenience it can't be beat. The materials you mentioned are great if you have the time, money and experience to deal with them, but they're probably overkill for a small tin boat and a one off application. You can get a gallon of Spar Urethane from any big box store for $30 and it will be more than enough to give several coats to all of the wood in the boat and Titebond III is also readily available and affordable at the same stores. To get a gallon of 2 part epoxy and cabosil, etc...shipped outside of FL from someone like US composites would probably cost about as much as the boat.

Titebond III is not waterproof .. moisture will degrade the Glue Bond.
Titebond III has a 50% shrink rate ( meaning any noticeable non-smooth surface will not accept the Bond of the glue ). BC Ply is not that smooth unless properly prepped.

Dont get me wrong here guys .. Im all for saving a buck for the DIY'er .. but it seems lately that its AOK to use the cheapest wood with the cheapest one part wood glue with the cheapest sealer/coatings for replacing a Transom or a stringer etc ...

Im just telling ya .. myself or any reputable shop would be using these materials for something so structural as a transom. We dont go to Home D. or local hardware shops to get our materials. There IS a reason for that .. trust me.

At times there are ways to "repair" something that is less expensive ( sure we have all the resins and glass overflowing at our disposal that make it more cost affective just to use what we have instead of buying a QT of something less expensive ). Its application to application.

I personally dont think Varnish and Woodglue is the answer to rebuilding transoms.

Gettin back to the OP ..

Tiger .. did you have something supporting the underside of your ply ? I saw the clamps sitting on the ground and sandbags etc for pressure. Did you use any other method for clamping ?

Peace and happy boating.

YD.

 

[kfa4303]

Re: Glass plywood for transom on Aluminum boat?

Show me a single transom that has be ruined be titebond III and/or Spar urethane? Using hundreds of dollars in toxic chemicals to seal up the transom for a little 14' tin boat is a bit beyond overkill. Don't get me wrong, if you happen to have the supplies on hand and know how to use them properly, go for it, but most folks don't and never will. Never mind the fact that they're not really necessary. Boats existed before epoxy, believe it or not. To be quite honest, you could probably not put nothing on the wood and in would still last well over a decade. Most old tinboats were made with unsealed plywood to begin with. Besides, the whole reason we're all here on iboats is because we are DIYers. Of course, the answer to every boating question is "go to the best shop and spare no expense." Well, drrrrrr. Yet, there's more than one way to skin a cat, and if I can find a cheaper, quicker, easier way to do it without sacrificing function, or safety then I say "go for it". Do as you like, but you'll be perfectly fine using glue and spar urethane. I promise

 

[itiger]

Re: Glass plywood for transom on Aluminum boat?

There are several 2X4's under the ply. The clamps were not sitting on the ground. The 2X4's are not visible just due to the view angle...

 

[floyd49]

Re: Glass plywood for transom on Aluminum boat?

There is a way to fix any thing ok, better ,best. In other word do i want to have to redo it in a few years or several years from now?