1982 Galaxy 16 foot bowrider TRANSOM repair questions!!!

[devildogae]

So I have just bought a 1982 Galaxy 16 foot bowrider. It had the entire interior stripped because it has rot from water. I've removed the floor and now the transom. So my question is about the transom. I measured before I removed it. It was very wet and most of the lower wood just crumbled out. Anyway, the total distance from the outside of the hull on most of the upper part was 2 inches. The lower part, and I mean the bottom ledge was 2.5 inches. Does this sound correct for a transom to have that much difference between the bottom and the top?

If this is correct, when I'm making the new transom with ply, how can I get .5 inch more thickness at the bottom? This seems to be a difficult task, and maybe it was a very simple answer. So I hope someone can chime in.

 

[ondarvr]

It's not going to make a difference in strength whether you make it 2" or 2.5".

​There may be some reason they did it, but unless you can identify the reason as you take it apart just go back with 2"

 

[CrazyFinn]

Welcome aboard!

A difference of that much top to bottom doesn't make sense - and even it was like that, just make the new one 2" all the way down. Two sheets of 3/4" plywood laminated together, a few layers of glass on the inside, and you have 2".

Post some pics when you can. You'll get a lot more useful advice!

 

[Woodonglass]

It will take more than 2 layers of 3/4" plywood and a few layers of glass to get to 2" Is this an I/O or Outboard powered boat. Pics would help alot. Whats the measurement at the top of the transom.

 

[ondarvr]

Yes, if it's an I/O you need to make it the correct thickness for that particular outdrive, that could be the reason.

 

[devildogae]

Top Side

 

[devildogae]

Top Side

 

[ondarvr]

You need to use the link in photbucket, copy and paste it here, then the pic will show in the thread.

​You didn't say if it was an I/O or OB

 

[devildogae]

Bottom

 

[devildogae]

It's an O/I and trying to do this on my phone, will get laptop and try and fix

 

[ondarvr]

I/Os have thicker transoms, and they only need it in a small area around where the outdrive bolts through, so it's normal. It makes little difference on the rest of the transom, so thinner is fine.

 

[Woodonglass]

Depending on what outdrive you have, it will tell you exactly how thick the transom should be. Usually + or - about 1/4"

 

[devildogae]

I have a pre-alpha one Mercruiser sterndrive with 120 engine

 

[devildogae]

It will take more than 2 layers of 3/4" plywood and a few layers of glass to get to 2" Is this an I/O or Outboard powered boat. Pics would help alot. Whats the measurement at the top of the transom.

I attached some pics now. Where should the glass layers be to build up thickness?

 

[devildogae]

No Title

 

[ondarvr]

Just get the dimensions required for your outdrive and go with that number, what's there now can be off from being crushed or swollen from water and rot.

 

[devildogae]

Just get the dimensions required for your outdrive and go with that number, what's there now can be off from being crushed or swollen from water and rot.

Thanks! I have the manual for the engine, and I can't find that information anywhere. I don't think they make a manual for the boat.

 

[ondarvr]

Give the make and model of the outdrive and someone here can probably get the info for you.

 

[devildogae]

1982 Mercury Mercruiser Type 1 (Pre Alpha)

 

[CrazyFinn]

1982 Mercury Mercruiser Type 1 (Pre Alpha)

You will need minimum 2" thickness. To be safe, no more than 2 1/4" or the spline might not engage properly. Same thickness all around the hole, flat both sides.

My comment on two layers of 3/4" plywood was based on what I needed on my boat. The outer skin (gelcoat & glass) was at least 1/4" thick, I laminated two sheets of plywood together, added one layer of 18 oz glass between the old skin and the new transom, and then a few layers on the inside to get to 2". This is how the original was as well - but with a thin layer of glass between the two laminated sheets of 3/4" plywood that apparently served to trap moisture really well!