Replacing Transom on Pontoon

[Snake334]

I recently purchased a 24' Playmate. It had been left outside and was in bad shape. My wife and I stripped it down to the toons, and completely rebuilt it. It had a blown 50hp Mercury. When I pulled it off, the transom was rotten. It was 2 pieces of 3/4" plywood. I have a 1998 Johnson 50hp 3 cyl. to put back on the boat. I am looking at repairing the transom with a piece of treated 2X12 between 2 sheets of 1/8" aluminum bolted into the transom. The transom is all aluminum except for where the engine mounts, which is wood. Does this sound like it will hold this motor?

 

[lncoop]

Re: Replacing Transom on Pontoon

I'm trying to wrap my brain around your design, but if I'm visualizing it correctly I don't see why it wouldn't be strong enough. Just curious though; when you say the board will be between two sheets of aluminum do you mean it will be sandwiched between them, or they'll be on either edge of the board? Pics of the pod would be helpful.

 

[Snake334]

Re: Replacing Transom on Pontoon

Yes, the board will be sandwiched between 2 sheets of 1/8" aluminum. The rear of the transom has a groove where the old wood was attached. So instead of putting 2 pieces of 3/4" plywood back there, I was thinking the 2X12 with the 2 pieces of aluminum would hold up better.

 

[lncoop]

Re: Replacing Transom on Pontoon

That should be fine.

 

[5150abf]

Re: Replacing Transom on Pontoon

You will still need to seal it at the top and bottom, once water gets in there it will make short work of the 2x12 unless it is treated then the problem is a reaction between the treated and the aluminum, they don't play well together.

I am on the fence with what you want to do, with plywood all the peices are glued together making one thick peice, with yours it is 3 seperate peices and a single peice of wood which is not as strong as the multiple layers in plywood.

It should work but I would personnaly go with the 2 peices of 3/4 ply glued together and sealed well, it is easier, cheaper and I think it will last longer.

You have my 2 pennies now.

 

[Snake334]

Re: Replacing Transom on Pontoon

Ok, I understand what your saying about the plywood. I didn't know the treated wood and the aluminum didn't play well together. I didn't even think about that. As for money, I had the sheets of stainless aluminum layin in my garage so they didn't cost me anything. The reason I thought about the aluminum, I have a ski boat with a 115 Mariner. I noticed a small crack at the top of the transom. When I took it back to the dealer, they repaired the crack and they also put a piece of aluminum inside the transom, top and bottom, to distribute the weight. That's what I was thinking about here. Use the aluminum to even out the weight on the transom. Would it be better to use the plywood and maybe just 1 piece of the aluminum?

 

[5150abf]

Re: Replacing Transom on Pontoon

On mine I have 4''x3'' aluminum pads where the engine bolts are to keep them from pulling through the wood.

The aluminum is pretty flimsy and won't add much if any strength to the transom but it is good for spreading the load of the bolts, your strength comes from the wood and my point was 1 1/2'' of plywood is alot stronger than 1 1/2'' board.

Either one will work, ply or 2x12, and if you glue the aluminum to the board the glue will act as a seperator and keep them from reacting and that is all you need, at work we use a really thin foam tape between the crossmembers and the wood, they just can't touch.

 

[Snake334]

Re: Replacing Transom on Pontoon

How does this sound? Take 2 pieces of 3/4" ply and bond them together, then bond the aluminum sheet on the inside of the transom.

Also, I was planning on using Grade 8 bolts to secure the transom, and SS to mount the engine. Should I use SS all the way around, or will the 8's be good?

 

[5150abf]

Re: Replacing Transom on Pontoon

That sounds like the best of both worlds, it is kind of a pain but drill all your holes then seal the wood, that way it won't start rotting at the bolt holes and should last a really long time.

 

[Snake334]

Re: Replacing Transom on Pontoon

I think I have decided on a different path. After researching this some more, I have decided to get some 4 X 1-1/2 X 1/8" aluminum tubing and cut it to fit my transom. I'm going to take it to the local welding shop and have it welded into a solid piece and then have it welded into my transom to form 1 solid piece. No wood, no rot. My uncle has a 32' Party Hut with this same setup and it has had no issues what so ever.

What do you all think?

 

[5150abf]

Re: Replacing Transom on Pontoon

If it is 1'' thick hollow tube 4'' tall I don't think it would work, it really isn't that strong,we have a similar tube at work and I really don't think it is strong enough to hold the motor on and once you weld it in and it doesn't work you are kinda screwed.

A plywood transom properly done will last for quite a long time, there really isn't a reason to reinvent the wheel here.

Our backboards at work are made from formed 3/16 sheet ad filled with wood to fill the gap, I don't think 1/8 tube will do it.

 

[DJ]

Re: Replacing Transom on Pontoon

For that HP-Good to go.

 

[Snake334]

Re: Replacing Transom on Pontoon

Well, after deciding on my plan for a new transom, I have ran in to another problem. I decided to go with 3/4 ply bonded together. After getting my measurements for the new transom, I cut the ply. The engine I am putting on the boat is an engine I just bought from a dealer that was taken off of another pontoon.

I was going to go ahead and mark my mounting holes on the ply before it was painted and sealed so it would be easier to hang the motor. Well, the motor bracket is 14 1/2" tall but the transom is only 9 1/2" tall.

Will the transom hold if I just extend it another 5 inches, or will I need to rig up some type of support since it's going that high?

 

[Snake334]

Re: Replacing Transom on Pontoon

I am looking at making a jack plate to raise the motor. I have found aluminum T6061 angle. It's 3"x3"x3/8" and I can get it in 4 ft length. If I use this to make me a jack plate, will it hold up? I have found it very cheap verses buying a jack plate.