Transom wood

[oigetit]

Hi all. I need new transom wood. Can somebody with the experience tell me how big the job will be. Weighing the decision to just buy a new boat or replace transom.. Thanks.

 

[Johnny]

Welcome to Water World !!
what size is the boat and how big is the motor ?

first off, replacing the transom wood is not hard at all - IF - you have
some woodworking/handyman skills and the handtools available to do the job ..........
Take your time, go slow, don't cause more damage to the boat hull
than what is already there. Don't use pressure treated wood.
Clean the hull metal behind the wood.... remove and treat all corrosion and prime.
3/4" CDX plywood is the most common replacement wood, preserved accordingly.

second: use the "search" button for transom replacement and dozens
of good threads will become available for you to gain the full perspective.
If you need the visual tutorial, there are several "transom replacement" videos on YouTube.

ask any questions you may have as you go through your project.

In your photo, remove all the fasteners that you can get to.
remove the top cap and corner braces.
the wood "should" come out by lifting straight up.
if it has been caulked or glued into place, you may have some resistance.
use the old piece to make the new piece and install the same way.





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[oigetit]

Thank you Johnny. This makes me feel like it is very doable. I just worry about the welded corners. Lots of tools, lots of diy ability. Thanks again.

 

[oigetit]

Sorry... forgot part of the previous post. The boat is a 12 ft lake jon (wider than standard jon). The motor is 9.9 Merc. I also am trying to decide whether to use ply, wafer, of douglas fir. Cant seem to find any posts about doug fir. It is the best thing to use for house parts that are out in the weather.

 

[Johnny]

there are posts here about using OSB wafer board - NOT a good choice.
most woods will give you good performance if preserved and coated properly.
I made some seats out of douglas fir. sealed, primed and painted as they should be.
I had to replace them 3 years later - on the second set, I used red oak - that also failed in 3 years.
now, I am doing both of my boats in natural Florida Cypress - carefully preserved as this
will be my LAST set of seats !!!! The transoms are all fiberglass panel - so there is no chance of failure.






keep doing your research

the general concensus will be ext grade plywood - properly sealed, primed and painted.






.

 

[DaleH]

the general consensus will be ext grade plywood - properly sealed, primed and painted.

^^ THIS ! ^^^

I have to replace the wood in my 12' tin Starcraft V-hull before next season. I'll make sure to take plenty of pictures and perhaps stitch the story together as a tutorial for one way to approach it.

 

[huntinfool]

Plywood is your friend. Some people use spar urethane. I'm a fiberglass man myself, so I'd either wrap it in glass or just pour a solid transom.
Good luck in whichever way you choose.

Sent from my XT1585 using Tapatalk

 

[oigetit]

Thanks everyone. I am feeling more comfortable about doing this project. I am sure that I will have more pitfalls for you to pull me out of. :lol:

 

[Al U Minium]

I have to do my stern too and looking through the posts, I will go with CDX exterior plywood. I need 2 pieces of 3/4 sandwiched to make my stern thickness. I want to use the 50/50 mix of varnish and mineral spirits to seal because of the humidity here. I was going to glue the 2 pieces together for strength. Do I seal the pieces before I glue them up and if I do can I still glue them up and what glue to use, wood glue or epoxy. I can get native cedar or even oak so is plywood still the best choice? Thanks for letting me tag on to your post.

 

[lckstckn2smknbrls]

Glue the two layers of plywood together first then cut and shape them to size, then seal the plywood.
I also drilled all the holes before sealing the wood.

 

[Johnny]

Dale H. advocates the technique of sealing the holes with epoxy - - -
if you know where the holes are going to be, mark them, drill out a 1" hole
in the wood, masking tape one side and fill the hole with epoxy - let it cure.
then, apply the 50/50 sealing varnish, two or more coats of straight varnish or paint.
after the transom is securely in place, hang your motor and then drill the appropriate
holes through the epoxy plug - that will insure water never gets into your wood from that point.
If you are unsure of the bolt placements, never mind, just fabricate your transom
and go from there....... try to seal the holes the best you can before final assembly.

that transom should last 10 or more good years.

 

[stinkfoot]

If you don't want to ever do it again, use https://www.kingplastic.com/products/king-starboard/ not plywood.

 

[CedarRiverScooter]

I use 3M4200 (or equivalent) marine sealer on any fasteners going into side or bottom of boat. I try to get the inside of the hole coated before fastener goes in, plus coat the fastener. A little messy but it will be waterproof. Just FWIW.

 

[DaleH]

If you don't want to ever do it again, use https://www.kingplastic.com/products/king-starboard/ not plywood.

I'd never use that as a transom material, it has the compressive strength, but flexes FAR MORE than plywood would in a purely 'structural' sense. King Starboard and the like flexes and bends way too much to be an effective transom material.

It also moves with temperature changes, so any fastener hole needs to be up to twiceX that of the fastener diameter, dependent on material thickness and size overall.

I LOVE it for making accessory items, but IMHO it is an extremely poor (and expen$ive) choice for a transom. That said, I have used it to add a 12" square or less 'transom pad' that is centered on the outside of the transom, for the OB mounting, but the transom core itself was plywood, properly coated and sealed of course.

 

[enginerd]

If you don't want to ever do it again, use https://www.kingplastic.com/products/king-starboard/ not plywood.

I'd never use that as a transom material, it has the compressive strength, but flexes FAR MORE than plywood would in a purely 'structural' sense.

I agree; HDPE is great for a lot, but not as structural material.

If you want to go with a composite for longevity, I would look at something like Garolite. My transom is fine, but if I had to replace it I was toying with the idea of buying a sheet of Garolite from McMaster-Carr; mostly because removing the transom from my Lone Star isn't a task I would want to repeat and a Garolite transom would be a permanent solution. Garolite is extremely strong and won't ever rot, but it is also extremely difficult to machine (many machine shops around here refuse to work with it) and it's heavier than plywood would be. I would probably stick with well sealed plywood.

 

[DaleH]

I would probably stick with well sealed plywood.

We took a deep-V center console, one with the large 'U' cut-out in the transom ... cut out the rear INSIDE skin to sub-floor, tied in new supports (knees) to existing stringer system, added new full-width transom of plywood epoxy coated and epoxied in place. Then added a add-on OB bracket that extended well off the stern and bolted a few Suzi DF-250hps on the rear.

That transom wood will OUT LIVE that boat ... for that you can be assured!

 

[oigetit]

I think I will scrap the douglas fir idea and go with marine ply and spar urethane. Local lumber yards have to order the marine grade plywood but only takes a few days. I have all winter :lol: Also thinking about Gorilla Glue All purpose All type waterproof glue for the plywood.

 

[DaleH]

Also thinking about Gorilla Glue All purpose All type waterproof glue for the plywood.

Scrap that idea quick and use Titebond III, see: https://festoolownersgroup.com/other-tools-accessories/titebond-iii-vs-gorilla-glue/

Gorilla glue breaks on the glue line in pull test ... whereas the wood shears at the weakest link in the base wood that is NOT on the glue line.

 

[lckstckn2smknbrls]

Marine plywood will rot just as fast as exterior plywood if not sealed properly.

 

[FishinLite]

This is a very interesting discussion.

Has anyone tried "Baltic Birch" plywood.
About the same cost as marine plywood.
Like marine plywood it has no voids.
Made with exterior glues.
Has more plies for given thickness.

The more plies would mean that it is probably stronger. How much I don't know.

Any input?