What wood to use to replace transom?

[SwampYankee]

I used marine ply and jamestown epoxy

 

[cron78]

You could thin it with mineral spirits a little or you could warm the wood by placing it in the sun which will open up the pours some. I put 3 coats of Marine Spar varnish (satin) with a light steel wooling between coats and it has lasted a long time. Now if you use plywood I would say then the fiberglass application is probably a good idea. I live in Florida also so i know all about Hurricane damaged boats..........we got plenty of em down here too on the southwest coast.

Thx. Gonna take your advice and work on the transom this weekend.

The wife and I went down to Cape Coral to volunteer for clean-up after Ian last fall. It was a mess close to the water but just a bit inland there were still plenty of trees and open businesses. Up here after Michael we went three weeks without power. It was humbling helping folks down there that had to strip their homes of all possessions down to bare concrete floors and wall studs, and put it all at the curb to be hauled away. Michael devastated my yard and spent about ten minutes in my living room with me before I got the front doors closed and barricaded with a couch and coffee table. We filled the entire roadside in front of our lot three times with just cut trees and downed fence and only a smattering of possessions. We were still blessed to have minimal damage to the house. Did learn a lesson from having to bath nightly in the pitch dark in our swimming pool...we needed floating soap because when you drop a bar of soap and it's dark and the pool bottom is sloped, you will not find that bar of soap until daylight.

 

[thill]

23/32 BC plywood is what I typically use, soaked in Thompson's Wood Preserver and Waterproofer, once it's cut to size. I've had very good, long-lasting success with it.

 

[Lawless Fishing]

I know it's been a bit for this thread. But have you thought of going with the liquid hardening rout. Where you form it up an pour it in the form and it hardens. It a 2 part mixture with fiber material in it. Can't remember the name but from the looks highly durable.
Just remember it's called Seacast. Ppl are also using it to replace stringers too..

 

[LDUBS]

Yes, I just can’t find any of the exterior grades that are not treated. Unless I’m getting this wrong. At HD and lowes I see “treated” 3/4 BCX plywood. The word treated, is what specifically threw me off since I know not to use “pressure treated”. Are they treated with different chemicals?

The full 3/4" treated stuff at the big box stores appears to use a copper azole treatment. Not to be used in contact with aluminum. Looks like choice is the 23/32" exterior ply. Two layers = 46/32, or 1 7/16", so 1/16 shy of the thickness you need. Just some blue sky on my part, but if you need the full 1 1/2", maybe a filler between layers using cloth & epoxy? However, before going to that trouble I would check with my local lumber store for 3/4 exterior.

But before all that, make sure the 23/32 stuff won't work. See @thill 's post above.

 

[Ghostryder65]

Great thread. We are also getting ready to replace a transom on a ‘61 Lone Star Big Fisherman my son bought on the side of the road this month. What is the reasoning for not using pressure treated wood? I’m not sure that’s what the kid is doing but I’d better make sure & tell him why.

The pressure treatment introduces Copper sulfide among other things to the wood. If it is against the aluminum it will react and eat the aluminum.

 

[thill]

I have used Seacast often and it is an excellent product.

You would probably be best to make a form and pour and level it, then install it into your boat after setting, rather than trying to pour it directly into the transom. Pouring directly would create a huge amount of work, trust me on that one.

 

[LDUBS]

I have used Seacast often and it is an excellent product.

You would probably be best to make a form and pour and level it, then install it into your boat after setting, rather than trying to pour it directly into the transom. Pouring directly would create a huge amount of work, trust me on that one.

I've heard and out of curiousity looked at that product. I like the product. Like most superior products it carries a superior price. I assume it would take 2+ gallons of the stuff to do a typical tin boat transom?

 

[thill]

I've heard and out of curiousity looked at that product. I like the product. Like most superior products it carries a superior price. I assume it would take 2+ gallons of the stuff to do a typical tin boat transom?

Probably a 5 gallon kit, I would think.

I'm pretty sure they have a good calculator on the website. That will make it easier.

For what it's worth, when you mix it, use as much fiberglass as you can for a casting. You don't need it to flow much, you just want it strong. If you form it right, it will be awesome and 100% permanent.

Why have I never thought of this for a tin boat? I've half a bucket sitting in my shop.

 

[Whidbeyboater]

I have been happy working with MDO / HDO plywood. Its commonly used for outdoor signs and reusable concrete forms.

It is similar to marine grade 100% void free but instead of water proof glue it uses a waterproof thermoset resin and comes with a one or 2 sided paper face sheet that looks nicer than plywood.

I sandwiched a piece of 3/4 and 1/2 together for my transom. Oversized all the thru holes and sealed all the edges and holes with 3 layers of epoxy. I haven't finished the project yet so its not water tested but I have heard great things about MDO and so far I think its going to hold up as good or better than anything else.

 

[cron78]

Update on the old Meyers transom I am working on. Work and life got in the way of fixing the transom last August, but it is cut out, sanded, and has the first coat of spar varnish on it today. Lesson learned is that planing white oak is a bear. I worked half an hour on my little Rigid benchtop planer and got nowhere. Didn't get even a sixteenth removed. Swallowed my pride and carried the wood to the millwork shop I bought it at years ago and they planed it down in three passes. The difference is that flat blade benchtop planers are not made to work on white oak. The shop has a 200 tooth planer that is huge and impressive. What else is impressive is that they didn't even charge me for the two minutes of planer time. Got it home and very carefully managed to cut the shapes I needed with my table saw and saber saw. Orbital sander works fine, too on the white oak. Just the planing was the problem.

Will finish the light sanding and varnishing and install for splashdown in two weeks.

 

[LaqueRatt]

I'd have applied a guide coat of paint and then took a belt sander to it. Fast and easy.