New plate on the back of the transom?

[Ira C.]

I have just finished putting a new transom in my 1967 Starcraft Mariner.I put a 1/4 in. exterior plywood plate on the back of the transom as was on the origional (three coats of paint - holes pre drilled) but when I bolted it down it cracked in one place beside a bolt & it curves out at the bottom just like the old one did.I am not at all satisfied with this arrangement as it is unlikely to last & is unsightly.
Can I just remove this plate & let the motor rest against the aluminum?
Or, is there a more suitable material than this thin plywood?

 

[SpinnerBait_Nut]

Re: New plate on the back of the transom?

I have seen some with a metal plate there.

 

[Ira C.]

Re: New plate on the back of the transom?

Putting an aluminum plate there makes sense. Is that what they put on the new ones?

 

[Bondo]

Re: New plate on the back of the transom?

Ayuh,.....

The advantage of the wood over the aluminum is,...
The motor can "Bite" into it,+ is less likely to Slip.......

 

[tylerr83]

Re: New plate on the back of the transom?

my '71 starcraft has a plywood transom pad also...i think thats pretty standard...the orignial was 3/8 ply i think on mine...replaced it w/ 1/2 that was scrap from the deck... shouldnt' curve though...most of those old starcrafts are really similar, even different models used some of the same hull styles with slight variation...there should be ten bolts through it...six that go through to the transom brace and four (one on each corner) so it shouldn't be able to curve at all...if you're outboard will fit over it try something a little thicker

 

[Ira C.]

Re: New plate on the back of the transom?

There are 10 bolts that go through the pad.The problem is it extends below a row of rivets which pushes the bottom of the pad out.I could cut the pad off just above the rivets and still have room for the motor. Or, I could go with a 1/2 in. treated plywood-I would have to buy a whole sheet and then longer bolts. I had much rather have the pressure treated!
At this point I have so much effort, pride, and money in this I hate to leave it the way it is. What shall I do...mmm?

 

[tylerr83]

Re: New plate on the back of the transom?

on mine that plate ends just above the rivets ,sounds like thats the problem, all the force/weight of the motor pushing against that area where the wood is bowed out slightly by those rivets. you want that plate to sit flush to the outer skin of the transom

 

[jameskb2]

Re: New plate on the back of the transom?

I wouldn't use pressure treated plywood, it will more than likely be treated with ACQ, and it is well known to eat aluminum FAST.

Every time it gets wet the chemical in the wood will attack the aluminum.

I'm a carpenter, and I have seen it in action. I removed (during a repair from a previous builder on site) aluminum flashing that ran from wall to an exterior deck. The flashing ran down the wall, bent at the ledger board (ACQ treated dimensional lumber) to run under the deck. As soon as we had the decking removed, we laughed....the aluminum flashing was GONE. I mean...eaten away. The edge looked like when you light newspaper on fire and tamp it out. Anywhere the ACQ treatment touched the aluminum was affected. Wicking included...anywhere the chemical came in contact with it.

It wasn't mill finish "tin can" flashing either, but a heavier grade coil stock painted on both sides.

FYI...

 

[TriadSteeler]

Re: New plate on the back of the transom?

Ayuh,.....

The advantage of the wood over the aluminum is,...
The motor can "Bite" into it,+ is less likely to Slip.......

Bond-O is absolutely correct about the slippage issue. If you still would like to use an aluminum plate, you could attach a piece of skateboard grip tape to help combat the slippage issue.

 

[Ira C.]

Re: New plate on the back of the transom?

I have now gone back and replaced my new pt plywood transom with exterior plywood. After reading all the pt and aluminum threads I relented and bought epoxy and started all over!
My original question was concerning the pad which has been resized and redone- it remains 1/4 in. exterior.
If I put an aluminum plate on the front of the transom (to proctect it) will the motor slip even though the pad is plywood.Did that make sense? Maybe I need to get over aluminum plates and put it back as origional!