I have searched this forum with no luck. I am replacing the rotten wood in the transom. I would like to replace it with something other than wood if possible. Any suggestions? Thanks for any advice.
Moving away from plywood is going to cost money. Here is some structural boat building foam:
http://www.jamestowndistributors.com/userportal/show_product.do?pid=1588&familyName=Divinycell
Or if you use plywood, use marine plywood (not treated plywood, “marine plywood” like Meranti or Okoume).
What size motor are you putting on this transom?
It will have a 9.9 on it. Price is not really an issue unless it becomes obscene, I just want to do it right. I am giving this boat to my nephew, therefore I can not afford any issues with it. Thanks again.
I’m not sure how thick you need it to be, but I’ve got some 1/2" white starboard that you could double up to get 1" thick. No rot and you can work it with the same tools you use for wood.
Bob Van Gundy
Marine Designs,Inc.
Custom Aluminum Fabrication
803-727-4069
There’s that “fake wood decking” at Lowes or HD its 1 inch thick ?
26’ Twinvee
Suzuki 175’s
www.creeksidemetalworks.com
There’s nothing wrong with using “Plywood”, if you seal it properly! Cut to fit, seal all edges, install; double if necessary. By seal I mean with a good Resin. Take your time, and it will outlast the rest of the boat!
quote:
Originally posted by Mixed NutzThere’s nothing wrong with using “Plywood”, if you seal it properly! Cut to fit, seal all edges, install; double if necessary. By seal I mean with a good Resin. Take your time, and it will outlast the rest of the boat!
Yep.
I’d like to hear BtY’s rationale for the increase in cost for marine plywood. From what I’ve read, marine plywood is made of the same material as regular exterior (unless, of course you go for something exotic) and uses the same glues. The only difference is that marine plywood has very very minimal voids in each layer of laminate. In regular exterior plywood, you can have knot holes and such that will give you holes in the face of the laminate or hollow spots inside the laminate.
Depending on what you expect the wood to do for you, you might not need the shell out the extra bucks for marine grade materials. Plain ole’ exterior grade stuff may be sufficient (well sealed, as Mixed Nuts says).
17’ Henry O Hornet
26’ Palmer Scott
Is this an aluminum jonboat with the wood to be used only in the area where the outboard attaches? If so, pressure treated plywood like a piece of T1-11 will work. As long as it won’t be continuously submerged it will last a good long time. Marine grade plywood will rot if it is not completely sealed or encapsulated in fiberglass.
Iain Pelto
Edgewater 185CC “Jumpin’ Bean II”
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Originally posted by PalmerScott[quote]Originally posted by Mixed Nutz
I’d like to hear BtY’s rationale for the increase in cost for marine plywood.
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It’s not my rationale. The poster, ceylon, said “cost is not an issue”. So, because cost is not an issue, I didn’t try to make it an issue.But, cost seems to be your issue.
"That Lovett guy blows..." - SLACK_LINE
quote:
Originally posted by BiggerthanYoursquote:
Originally posted by PalmerScott[quote]Originally posted by Mixed Nutz
I’d like to hear BtY’s rationale for the increase in cost for marine plywood.
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It’s not my rationale. The poster, ceylon, said “cost is not an issue”. So, because cost is not an issue, I didn’t try to make it an issue.But, cost seems to be your issue.
"That Lovett guy blows..." - SLACK_LINE <hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote"> I'll have to agree that if cost is not an issue, a nice piece of Okueme would be an attractive addition to any hull. [img]http://www.clcboats.com/images/photos/products/sapelezoom.jpg[/img] --------------------------- 17' Henry O Hornet 26' Palmer Scott
PalmerScott, you and I and MixedNuts would not spend more than what a piece of exterior grade plywood costs. You will gain very little by using more expensive material. But, ceylon seemed like he needed to hear, ‘what else is out there’ kind of information. So, i gave him a synthetic kind of material and (not that he asked for it) what is considered one of the the best wood material in boat building.
If he asked, “what should I replace my jon boat transon with”, I would say, "use treated plywood and it will last a good long time. It’s a jon boat!
The problem with the pretty picture you found of the Okoume, he should cover it with epoxy and paint. And once it’s covered, only he and God would know what was under the paint. 
He should just use good exterior plywood. It will last a long time.
One more point, don’t let the newer grades of “treated” plywood come in direct contact with aluminum! It corrodes it fairly quickly!!!
“Marine grade” plywood is a farce, unless you are going for cosmetics as stated above. One can just fill any voids that appear on the surface of exterior grade plywood and seal it very well with epoxy resin. Built a 28’ sailboat out of exterior ply vs marine ply and saved thousands of dollars by using it.
Didn’t know about the new “treated” ply attacking aluminum, but It makes sense, the new stuff attacks standard galvanizing hence the need in the building industry for “Z max” coating on metal brackets in contact with it and the new coating one finds on screws.
For a john boat, I’d definitly just use a piece of exterior ply coated with epoxy.
Russ B.
God is great, Beer is good, People are crazy
quote:
Originally posted by Top2Bottom1“Marine grade” plywood is a farce… Built a 28’ sailboat out of exterior ply vs marine ply and saved thousands of dollars by using it.
Russ B. God is great, Beer is good, People are crazy.
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Did you sell this boat? If so, did you make it clear to the buyer that you did not use marine plywood? I would consider it a significant question if I was looking at a boat for sale especially a boat like a 28’ sailboat.I hope you don’t take this as a criticism or attack. There is No ill will intended. I am curious about this though.
If you haven’t found what you are looking for yet, drop me a line. I have a boat shop and I carry the compostie material for transons.
Glass
sold it long time back after delivering it to Hawaii from WA state as part of the sale, sold it to a fellow who made furniture for a living and we discussed the pros and cons of marine ply for hours. Consensus was that if money were no object, marine ply would be first choice but in 99% of cases ext. ply coated with epoxy is just as good. My nephew who lives there saw the boat in a anchorage on Kauai last summer.
Boat was a “Thunderbird” which was actually designed at the request of the plywood industry by a Seattle designer.
One thing I did do to the plywood (trick my dad showed me) was to try and find any interior void between the laminates of ply by tapping on each sheet face with a small hammer then once found, drill a 1/8" hole into the void and inject it with thickened epoxy to fill it.
quote:
Originally posted by Top2Bottom1sold it long time back after delivering it to Hawaii from WA state as part of the sale, sold it to a fellow who made furniture for a living and we discussed the pros and cons of marine ply for hours. Consensus was that if money were no object, marine ply would be first choice but in 99% of cases ext. ply coated with epoxy is just as good. My nephew who lives there saw the boat in a anchorage on Kauai last summer.
Boat was a “Thunderbird” which was actually designed at the request of the plywood industry by a Seattle designer.One thing I did do to the plywood (trick my dad showed me) was to try and find any interior void between the laminates of ply by tapping on each sheet face with a small hammer then once found, drill a 1/8" hole into the void and inject it with thickened epoxy to fill it.
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First point; I really appreciate the thorough answer and am relieved you made the boat buyer aware that you did not use 'marine plywood". There are no building permits required to build a boat and the care and quality is left to the builder. This could be dangerous/deadly. Hope you understand my concern.Second point; you looked for and ‘tried to find the interior voids’. I was concerned that people reading this thread might think that “marine plywood” and “exterior plywood” were the same. But, as you pointed out, you looked for voids in the “exterior plywood” you used. “Marine plywood” is specified to have NO VOIDS. There are many differences in the two materials. It is obvious that you know that they are different and know what to do with the “void flaw” of the “exterior plywood” material. I just want to let people know that this is only one or the differences.
For a jon boat, marine plywood is pretty extravagant in my book. For a boat that go
I’d build the same boat tomorow without filling the interior voids and sail it around the world in a heartbeat . I’m sure that I was only able to find maybe 50% of the voids and fill them, the voids I did find were in the second ply down only. It was a matter of I had a lot of time, but little money so I spent hours upon hours going over every sheet. Main reason for filling all the voids close to the surface I could find was I didn’t want to run the chance of “popping” one after the boat was finished by hitting the hull lightly with a dinghy,anchor, etc.
Correct me if I’m wrong here but I thought the only difference between marine ply and ext ply is the lack of voids in marine ply and it is usually more available in long lengths. Pretty sure both use waterproof adhesive.
I will say tho that my knowledge of “marine” ply came a long time back, I’m sure there has been tremendous improvements in both grades of plywood since then.
(no criticism or attack taken whatsoever! I can talk about boat building stuff all day long and I’m never too old or proud to learn something new or a better way to do something!) 
Russ B.
God is great, Beer is good, People are crazy
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Originally posted by Top2Bottom1Correct me if I’m wrong here but I thought the only difference between marine ply and ext ply is the lack of voids in marine ply and it is usually more available in long lengths.
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The only reason I have participated in this thread is the civility of the discussion of all who have contributed. Thanks.As far as what I have seen about the production and specifications of exterior grade plywood and marine plywood, the only thing that they both have in common is that they both use waterproof glue. The shear strength of marine plywood is higher, the exterior veneer is thicker, the interior layers are of equal quality to the exterior layers, there are no hidden voids, etc…
Many people look at how pretty it looks and seen to think that this is why it’s made. Actually, the reason it looks so pretty is because, quality wood just happens to look pretty. It is almost always covered up. So much for the pretty factor.
I don’t build boats. I don’t sell wood and I have never bought marine plywood. My interest in knowing about the material is a result of my deep appreciation of all quality construction; boats, airplanes, houses, furniture, fly rods, etc. And I was fishing ALL day today so, wood is not my passion.
Amen to that! my kind of discussion here, civil, about boat related stuff and the likehood of learning something new! (maybe we’ll start a trend) Looked like an awesome day to be out on the water fishing, unfortunantly I spent most my day working on boat motor:(
I was under the understanding tho that marine ply actually had thinner veneers yet more of them, thus giving it the higher shear strength or maybe it is just the middle veneers that are thinner??
Date with my pillow now. zzzzzzzzzzz
Russ B.
God is great, Beer is good, People are crazy