What Wood or other Material to fix Transom on Alum.Boat

[OptsyEagle]

I have a 70s aluminum boat made by Springbok. The wood on the transom is getting a little rotted. I am wondering what is the best type of wood to replace it. Perhaps they have a plastic material for this now?

Also, the screws that hold the wood to the aluminum boat. Some of them are under the water or close to under the water. Do you fill the threads with sealant. I do have some 3M #847 that I used to seal a lower unit of a 1961 5.5Hp motor. Would that stuff work or is it needed?

Any help is appreciated and any other useful tips. Thanks.

 

[metriccrescentwrench]

Re: What Wood or other Material to fix Transom on Alum.Boat

Usually the correct way to repair a transom is with marine grade plywood, and I use epoxy to seal the wood (West Systems, for instance). There are a few materials out there that people have used in place of wood, I think StarBoard is one, but I don't have any experience with that. It's fairly expensive though, but I believe that it's just HDPE. If it's a relatively small boat with a small engine I'd be comfortable using a sheet of HDPE of the proper thickness, you can buy it from McMaster Carr. (I made my ski locker cover and swim platform out of HDPE, it stands up well to use). If it's not just a small engine I'd do it right with marine plywood.

As far as sealing screws, the proper product to use for that is 3M 5200.

 

[OptsyEagle]

Re: What Wood or other Material to fix Transom on Alum.Boat

Where would one get marine plywood. Is that a product that a home depot or lowes would sell?

 

[JB]

Re: What Wood or other Material to fix Transom on Alum.Boat

I agree with MCW. 3/4" to 1" Marine plywood is probably your best bet for the buck. Seal it with epoxy.

If you are willing to go for the best, regardless of price, look into WhaleBoard, the indestructible stuff used by Boston Whaler. Your transom would probably be worth more than the rest of the boat and last longer, too.

 

[metriccrescentwrench]

Re: What Wood or other Material to fix Transom on Alum.Boat

Where would one get marine plywood. Is that a product that a home depot or lowes would sell?

No, the big box stores don't carry it (at least not the ones in my area). It took me a bit of searching to find a specialty lumber yard that sells it, just start calling the lumber yards nearest your location and work out from there.

 

[jayhanig]

Re: What Wood or other Material to fix Transom on Alum.Boat

Where would one get marine plywood. Is that a product that a home depot or lowes would sell?

I found some at the same place which supplies me with hardwoods for woodworking. When you find the local supplier of cheery, pecan, and mahogany, you've probably found the guys who also sell marine plywood.

You should be aware that marine plywood is no more waterproof than any other plywood. What makes it different is the superior lamination between layers. As others have said, be sure to seal it with an epoxy resin like West Systems 105.

 

[saumon]

Re: What Wood or other Material to fix Transom on Alum.Boat

Where would one get marine plywood. Is that a product that a home depot or lowes would sell?

If your local hardware store doesn't have marine plywood, check if they can order exterior grade BC fir (Douglas fir) plywood. It's not cheap either but it will do the job, covered with epoxy resin.

 

[JB]

Re: What Wood or other Material to fix Transom on Alum.Boat

Do not use any plywood other than Marine Grade or cabinet grade. Exterior grade has voids and too few laminations to compromise its strength.

 

[metriccrescentwrench]

Re: What Wood or other Material to fix Transom on Alum.Boat

Do not use any plywood other than Marine Grade or cabinet grade. Exterior grade has voids and too few laminations to compromise its strength.

EXACTLY. As soon as you work with marine grade plywood you'll understand the difference between that and normal plywood. All the voids are filled during the manufacturing process, whereas for standard plywood it's not at all uncommon to find holes in the interior plies. Those holes/voids are weak spots/stress concentrators which will lead to structural failure long before marine grade plywood would fail.

NOW, with all that, what size boat and what size engine are we talking about here?

 

[OptsyEagle]

Re: What Wood or other Material to fix Transom on Alum.Boat

In my case a 14' aluminum boat and the largest motor would be a 15 Hp.