What wood to use to replace transom?

[LaqueRatt]

Airshot is correct! All the cedar I've seen you could break over your knee. I'd use #2 pine before I'd use cedar.

 

[Al U Minium]

Wood boats planked with cedar go to sea in yachts and commercial vessels.



It's very good looking and bugs don't like it

 

[airshot]

I do believe those cedar planks were criss-crossed to give lateral strength not single layers. That is beautifull looking and for a very small motor will be fine, but for bigger motors with power, not sure it would be strong enough unless cross lapped and laminated. Damn nice looking though !!

 

[St.Clair Flatsrat]

Conventional wisdom on these boards is it is perfectly OK to use exterior grade ply. The consensus is that the added benefit of a marine grade, which is basically elimination of voids, adds quite a bit of cost (translate, not worth the extra $$ to many of us).

In my mind sealing the new transom wood has got to be a #1 best practice. I"ve used the Total Boat penetrating epoxy sealer. Like you say, coverage is pretty good. Another product highly recommended by long term member @DaleH is Raka epoxy.

I believe the name of a marine grade material is called Coosa board. Chck out Bloody Decks website. Some of its members have utilized this material

 

[LDUBS]

I believe the name of a marine grade material is called Coosa board. Chck out Bloody Decks website. Some of its members have utilized this material

I've heard of that stuff. It sounds like a superior alternative to marine grade plywood. I also always hear it is pretty pricey.

 

[Lost But Happy]

Never heard of it till today. Cool stuff. Very spendy. 3/4" x 2' x 4' $108.

https://coosacomposites.com/

 

[thill]

That doesn't look like cedar to me. More like Brazilian Cherry, a south american hardwood, or something similar. Very strong stuff.

 

[AlanT]

Never heard of it till today. Cool stuff. Very spendy. 3/4" x 2' x 4' $108.

https://coosacomposites.com/

I used Coosa Board for my deck material. Lighter and stronger than plywood and doesn't absorb water, but doesn't hold screws as well as plywood. You need to take extra steps if you are going to screw something that requires structural strength, such as a leaning post. I did not. I bought it before prices skyrocked and paid a little over $200 for a 4X8 sheet of 5/8" Bluewater 26 due to span between ribs. By comparison 1/2" marine plywood was about $80 a sheet at that time a few years ago. I've seen Coosa used to rebuild transoms and requires fiberglass. The weight savings is significant. I didn't need additional strength on my deck and just painted it with a tread paint.

 

[thill]

Coosa board is great stuff. I use it in fiberglass boats. In fact, I have a center console I'm about to restore, after I finish this Spectrum aluminum boat, and I'm going all Coosa. I also bought it before the prices went crazy.
For a tin boat, if you had a boat that you wanted to keep for the foreseeable future, it would be a good option, if you could justify the cost. There are lots of guides to using Coosa online.

 

[nate665]

I needed 5 feet width for my transom and when you try to get coosa board over 4' it gets insanely pricey was my experience.

 

[thill]

Alabama cedar might be something closer to Cypress, but I'm not sure

 

[LDUBS]

Alabama cedar might be something closer to Cypress, but I'm not sure

I'm not sure either. There seem to be a lot of varieties of both cedar and cypress trees. I have a 50'+ tall Deodar Cedar in my yard. It is a beautiful tree.

 

[AlanT]

I needed 5 feet width for my transom and when you try to get coosa board over 4' it gets insanely pricey was my experience.

The width across my floor boards is 64 1/2". You should have seen me with graph paper laying out each board to the fraction to minimize waste. I was able to do the entire deck with two 4' X 8' sheets. I used some marine plywood treated with penetrating epoxy under the console so I would have all the sizes to to complete the rest of the deck. I only had a few small pieces of coosa left over. I treated it like gold. It was quite the planning effort.

 

[user 33797]

Fiber glass resin without fiberglass cloth will not last long. It will peel off the wood.

Not necessarily true... Curing it to rock hard form, defeats that problem.

 

[user 33797]

What kind of wood do I need to use to replace transom on my 14’ Jon boat? Also do I need to treat it with something to keep it from rotting? And is there a type of wood that will last that requires no treatment?

Honestly, after reviewing the numerous thread additions, there are really great points to consider here. However, I'd offer potentially, a simpler solution to the many well made points, specifically when it comes to cost compensation to the project.

I was really concerned with this subject and mutually digressed into costs to replace such a small transom, even on MY tiny 14' Sea Nymph, though, I wanted it to last for the remainder of its life. I decided to go with REGULAR 3/4" plywood, but apply at least 3-4 coats of fiberglass resin and sanding in between. Note; I live in Tucson, AZ so I accomplished this with dry and very hot conditions and over a two week period giving into extremely quality drying sessions in between. That being said, I have a rock hard application that no doubt, nearly a year later has shown zero deficiencies what so ever. I consistently change out my motors on the transom and it has yet to damage/pierce the epoxy base much less even being concerned about the wood becoming infiltrated. So, the answer to MY questions was answered using leftover 3/4" plywood, non marine grade and less than $40.00 of epoxy resin. Being an amateur, I believe I got the best bang for my buck in my application against cost and for the size of my watercraft. Sometimes we overthink things and Transoms are one component we want done correctly but I do believe this was a success on a nearly half-century old chasis and will likely outlive the rest of it.

 

[airshot]

What is done with the wood after repairs are key!! Some folks just store their boats outside, tipped up to drain, get clogged up with debris, left those new repairs set in water/ moist debris etc. Did a transom repair on my jon boat, over 10 years back and it looks like new today....I just used plain ole plywood and sealed with thompsons and another off brand wood sealer. BUT....it sits under a lean to, upside down, no water contact until it is being used. Have numerous friends that have done similiar repairs with great sucess, the biggest issue is to protect the repair after you finnish it. Mother nature and her sun, can damage the best sealants over time. Lasting a lifetime is not that difficult, if we follow thru after the repair...

 

[LaqueRatt]

I sort of dance to my own drummer at times, but really does it matter? Seems like such a cheap easy project, on most boats anyway. Do I really care if I have to do it again in a few years? Pretty sure if just used whatever plywood I had handy could knock this out in a couple hours for zero money. BUT, if one was willing to coat it with most ANYTHING it may well last a long time. Why wouldn't it? My picnic table sits out all the time. Rain, shine, snow, and I just give it a quick coat of latex every few years. I've replaced a couple boards, but most are still doing just fine after 25 years! My boat lives under a cover much of the time and the transom wood rarely sees more than a small amount of moisture. Outside only.

 

[Al U Minium]

I do believe those cedar planks were criss-crossed to give lateral strength not single layers. That is beautifull looking and for a very small motor will be fine, but for bigger motors with power, not sure it would be strong enough unless cross lapped and laminated. **** nice looking though !!

Thank you !

I spent a long time restoring that boat and I wanted it to outlast me. That boat went through Hurricane Ivan and survived getting ripped away from the dock area and tossed into a field.

 

[thill]

I sort of dance to my own drummer at times, but really does it matter? Seems like such a cheap easy project, on most boats anyway. Do I really care if I have to do it again in a few years?

True with some, but not all of them are easy. I'm doing a Spectrum 17 sport that is a major undertaking. Literally, I have had to cut the boat apart and weld it back together. Definitely don't want to EVER have to do this one again.

https://www.tinboats.net/threads/1994-spectrum-16-sport-rebuild-bouncing-ideas-around.49976

 

[LDUBS]

Oops. Double post.