Aqua-Plas for Transom?

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Sswing
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Aqua-Plas for Transom?

Post by Sswing »

I have been following this form for years, but only soaked in information. Never posted before. I now have a question I can’t seem to find a answer to. Last year I finished a complete rebuild on my Carolina Skiff. Used Okoume for the transom. Recently, my cousin and I acquired a 23’ Glass Pro that is in need of a deck and transom. I am very familiar with glass and wood, but have never used anything else. For our 23 I would like to go with something that will last a very long time. It also has a bracket with a 225 hanging off the back. Therefore I am hesitant to try new things. I saw a post about Aqua-Plas III, but not much was said regarding it and transoms. I would like to know if anyone has used this product with any luck for their transom? :help:

fallguy1000
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Re: Aqua-Plas for Transom?

Post by fallguy1000 »

I did for a very small 30" wide transom. I recommend you stick with coosa bluewater 26.

Otherwise do a side by side comparison for sheer and compressive strength.

Actually, I used core-lite board I think, but same type of stuff.
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wpstarling
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Re: Aqua-Plas for Transom?

Post by wpstarling »

not sure on aqua-plas so my following statement may be worthless but I used nida-core on my small 15' skiff transom but it's only ~48" wide at bottom of transom and I'm only running a 15hp on it. I also wrapped it in 1708 but i don't think i'd be too sure of it with a bigger motor without putting more layers on it inside and out.
Boats restored: 1973 Glastron CV16, 1990 Proline 17 CC, 1993 Bass Boat
Boats built: custom 15ft flat bottom skiff, Soon-to-be-built TX18 (originally dborecky's build)

Sswing
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Re: Aqua-Plas for Transom?

Post by Sswing »

Thank you for the advice. I ended up reaching out to Piedmont Plastics. They said they didn’t have anything they would recommend for a transom. I guess it’s back to the battle between coosa and ply. After pricing out coosa I am leaning hard towards okoume.

Fuzz
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Re: Aqua-Plas for Transom?

Post by Fuzz »

I like nidacore for a lot of things but the transom is not one of them. It is my understanding it is not made for the kind of forces that the transom involves. If you go with plywood in the transom I would look at meranti or even fir. Both will be heavier but they are stiffer. And this is a place for stiffness. Glass covered and any holes dealt with the right way and it should last. What kills plywood transoms is poking holes in them and no proper sealing done.

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Re: Aqua-Plas for Transom?

Post by TomW1 »

Okuma or Meranti ply with the proper number of layers for your motor HP covered in fiberglass and properly tabbed in the corners and on the bottom will last just as long as foam, so that is what I would go with. Okume is lighter than Meranti if you want to save a little weight. The number of layers of wood and fiberglass you will need depends on the HP of your motor.

Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

fallguy1000
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Re: Aqua-Plas for Transom?

Post by fallguy1000 »

Most of the time, improper penetration is the downfall of the plywood transom.

Guy punches a hole in it for a cable clamp for a stern light wire down low, no overbore, no rebore, and it rots.
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TomW1
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Re: Aqua-Plas for Transom?

Post by TomW1 »

fallguy1000 wrote: Mon Aug 22, 2022 8:03 pm Most of the time, improper penetration is the downfall of the plywood transom.

Guy punches a hole in it for a cable clamp for a stern light wire down low, no overbore, no rebore, and it rots.
Yep, any hole you bore in the transom has to be thoroughly coated with resin to prevent rot. Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

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Re: Aqua-Plas for Transom?

Post by Sswing »

I have decided to go with Okoume for the transom. I found a local lumber yard that can get it for a very reasonable price. Also it will hopefully save on some weight. By the time I am done over building it, I will need all the weight savings I can get. After seeing all the pictures of brackets falling off online. I am going to make sure it takes the boat with it. I have looked and looked for a recommended transom thickness. I have a outboard bracket with a single Yamaha 225 hp hanging off the back. Everything I have seen is 2” to 3”. Not much out there that really breaks it down. If I remember correctly, the CS25 transom is 2 1/2”. I believe I am going to go with 4 layers of 3/4” okoume to make it 3”, tab all the way around two or three times, then 3 or 4 layers of 17oz biaxial to cover and tie a few feet into the sides and bottom. Using all Marine Epoxy. Still working out the plan for adding a live well to the transom. I will add two knees on either side of the well. The way the cap and transom meet make things difficult.

fallguy1000
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Re: Aqua-Plas for Transom?

Post by fallguy1000 »

The main thing is to do the interlaminar bonds well. The number one error in ply to ply bonding is failure to precoat the wood. The wood will drysuck the resin from the thickener leaving a weak joint.

The number two error on a ply transom is skipping overboring and reboring holes and believing 4200 or 5200 good enough.

When I did face bonding here; it was all done under 9-10" of mercury under vac. According to my reading, the best bondline is 40 mils or 1 millimeter and I attained it woth the vac and using 1/16" vee trowel on both sides of the panels.

The tops of the vees should not collapse after applying, and of course only on precoated wood.

Make sure to use pins to locate the panels. I like aluminum nails that stay in the panel in drills holes.

Another common error is leaving the top plies exposed; they must be glassed over.

Good luck. It will be strong, done right.
My boat build is here -------->

viewtopic.php?f=12&t=62495

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