What type of wood for a 2x4 transom support brace?

[Roadblock]

I'm redoing my transom on m 1970 Mirrocraft Ski-N-Troll and one of the support is a 2x4 plank.

The actual transom is 2 sheets of stacked 3/4 inch which I'm going to use Roseburg 3/4 Marine Plywood coated with West System for that.

The 2x4 support wouldn't work out of Plywood due to the way the bolts come threw the board sideways.

I'm told you can not get 2x4 plank-wood in Marine grade. What should I use? I have West System to coat all of my Marine grade wood with so it would be nice if the 2x4 would accept a resin.

I've included a pictures so you can see what I'm referring to when I say "support".

 

[rallyart]

Re: What type of wood for a 2x4 transom support brace?

Cedar or Redwood handle moisture. Fir is strong and not expensive. If you coat the board in epoxy it will be sealed and secure whatever it's made of. Of course Teak is wonderful but it is a bit expensive.

 

[kfa4303]

Re: What type of wood for a 2x4 transom support brace?

Cypress is water resistant as well, if you can get it. However, as long as the wood isn't pressure treated you should be fine. IF looks don;t matter, you could even use a regular, non-PT 2"x4" and coat it with the leftover epoxy and/or spar urethane to seal it.

 

[steelespike]

Re: What type of wood for a 2x4 transom support brace?

White oak resists rot and is very strong. But may put you in the poorhouse.
White oak has been used in boat framing since adam was a little boy.
Would a piece of aluminum angle work.The outside dimension would be the same.
Just bolt it in place with short bolts.Of course the aluminum probably would be pricey too.
But no worries about rot.

 

[Scott Danforth]

Re: What type of wood for a 2x4 transom support brace?

why not build a laminate out of the marine ply?

 

[Grub54891]

Re: What type of wood for a 2x4 transom support brace?

why not build a laminate out of the marine ply?

Ya beat me to it^^

 

[jigngrub]

Re: What type of wood for a 2x4 transom support brace?

I would do away with that 2x4 and use aluminum angle instead. 1-1/2" x 1/8" thick angle will be stouter than that 2x4 and it won't rot.

That 2x4 does not look OEM (especially with those rusty bolts and washers sticking through it) and I think a PO jack-legged it.

 

[jbcurt00]

Re: What type of wood for a 2x4 transom support brace?

Jig, I thought of that ^^^, but the knee braces also tie to the bottom of the 2X. A stout C channel maybe?

 

[shaw520]

Re: What type of wood for a 2x4 transom support brace?

Jig, I thought of that ^^^, but the knee braces also tie to the bottom of the 2X. A stout C channel maybe?

...looks oem to me too.... many good woods to choice from,.. but if budget is concerning then redwood/cedar is an affordable choice.

 

[Roadblock]

Re: What type of wood for a 2x4 transom support brace?

I would do away with that 2x4 and use aluminum angle instead. 1-1/2" x 1/8" thick angle will be stouter than that 2x4 and it won't rot.

That 2x4 does not look OEM (especially with those rusty bolts and washers sticking through it) and I think a PO jack-legged it.

I was just speculating based on what I see. This is my first boat and I will be the first to tell you that I know nothing about boats but it sure looks original.

I'll have to take a couple close up picture but there is some foam spray stuff inside of that center brace that squirted out when it was originally built, in the corners where the brace and 2X mate. It's stuck to the 2x4.

Sure looks like original factory foam to me. Looks like the same dry rotted stuff that is in the bow and in the gunwells. It's dried on in such a way that if the board had been replaced, it would have come off with the board. Follow what I'm trying to say?

I actually emailed some pictures to Mirrocraft and the V.P. replied asking me for my serial number. He is going to get me all the info on the boat and original build he can for my restore project.

 

[bigdirty]

Re: What type of wood for a 2x4 transom support brace?

Being a machinist, I'd go for the aluminum angle :lol: and really, you could just cruise around to your local machine and/or welding shops, probably score something out of the short ends or even scrap bins for next to no $$$.... unless you want to do an 'all original' resto, then wood it is, whatever type happens to be in there...

 

[Grandad]

Re: What type of wood for a 2x4 transom support brace?

I'm with steelespike. I'd use oak if staying with wood. If you go aluminum, you might find an extruded rectangular tube that's strong and approximates the dimension you need. - Grandad

 

[jigngrub]

Re: What type of wood for a 2x4 transom support brace?

The 2x may be factory, but I haven't seen that application before.

I'm curious to see what it looks like behind the 2x, namely the lip on the splashwell pan... does the splashwell pan have a lip or is the reason for the 2x to support the pan?

With 3 transom braces, 1-1/2" thick transom, and that Hugh Jass splashwell I'd say your transom is very well supported... you couls dang near hang dual 300s on that sucker.

Depending on what the splashwell looks like behind the 2x I might go with 2 pieces of 1 1/2" angle to make a homemade C channel if that would stick out far enough to catch the holes on top of the transom braces.

If I went with wood, I'd go with a fir 2x4. It's straight, strong, light, and readily available at any lumber store. I would of course quadruple coat it with epoxy resin for preservation.

Post pics and let us know what you find when you get the transom disassembled.

 

[jbcurt00]

Re: What type of wood for a 2x4 transom support brace?

I thought about it some last night, and I can't remember ever seeing a transom w/ multiple knee braces that weren't all the same......

Multiple knee braces are fairly common, but shouldn't they all be the same? Based on your video, that I watched a while ago, I also can't remember seeing foam filled gunwales, like yours, on any other vintage boats, tin or glass.

My fall back is still going to be that there's been extensive work done by someone, and until you peel all the layers back, it may be extremely difficult to tell what was factory & what isn't. Unless someone else has the exact same year & model Mirrocraft, it's still all factory, AND stumbles upon your thread(s) & pix, and posts up detailed info & pix of theirs.

The knee braces just add to the huh? factor........

 

[bassmanhb]

Re: What type of wood for a 2x4 transom support brace?

Jig,

My mirro craft had the same layout for the transom.... I just used another 2x4 with 4 coats of epoxy resin and 3m 5200 in the bolt holes and built it back the way it was... that 2x4 on its side actually adds a lot of strength to the transom.


bass

 

[jigngrub]

Re: What type of wood for a 2x4 transom support brace?

Jig,
that 2x4 on its side actually adds a lot of strength to the transom.


bass

No doubt!

... and I really dig the overkill on the structural design of these transoms!

 

[fishrdan]

Re: What type of wood for a 2x4 transom support brace?

Off subject, but what type of plywood is the deck made of? Looks greenish from the pics. Is it treated plywood?

 

[Roadblock]

Re: What type of wood for a 2x4 transom support brace?

First off I want to thank EVERYONE for there feedback and suggestions. Sorry for being silent the past day or two, I've come down with the stomach flu and I've not even gone into work or touched my MacBook.

Off subject, but what type of plywood is the deck made of? Looks greenish from the pics. Is it treated plywood?

It definitely looks like pressure treated wood. It's actually laid over the factory deck wood which is rotted to hell. I'm replacing that at the same time I do the transom.

I'm taking the boat out on Saturday to go fishing because, well, I wanna go fishing but then Sunday I'm going to start drilling rivets and cutting bolts.

I plan to take a crap ton of before, during each stage of the trip down and after it's call pulled apart. Then during each stage of the rebuild.

As for coating, I'm going to coat everything in West System. I've already got the West System sitting here.

While I'm thinking about it, what type/grade of rivets, bolts etc should I be using?

 

[Roadblock]

Re: What type of wood for a 2x4 transom support brace?

Thread update! OK so the plan is to pull the motor and prep for the rear end tear down. I'm going to do before and after pictures of each stage as posted above. Going to take pictures with the motor on and after it is pulled. Then I'm going to start with the splashwell and once that is off take a bunch of high quality photo's of what I find under there etc.

I have a separate restoration thread going so I will most-likely post the photo's in that thread and link to it from here. I made this post specifically to get input on what type of wood to use for a 2x4 so I kind of what to keep all of the work in the restoration thread!

 

[jbcurt00]

Re: What type of wood for a 2x4 transom support brace?

Straight grain Douglas fir