Transom repair

[David]

Talk to me in 30 years. My Allison is all composite except the wood in the dash. My new boat will have a wood transom and balsa core.

My my brother has a 1989 boat and the wood transom is sound.

unless you are making a dedicated water ski boat or plan on too heavy a motor, put the gas tank in the rear.

[Ramonepb]

Thanks David
Its going to be a speeder for me but the wife will be going along occasionally!
I want a 12 gallon or maybe a little bigger. This crossflow loves gas!

[tunnels]

Why couldn't you make a transom or stringer out of just glass? It would be heavier than a cored panel, but would as tunnels said last 4 ever. I built many boats with a solid glass stringer system. My V-King has a solid glass stringer (box style) I would go as far as to say the majority of production boats now use a pre formed solid glass stringer grid. When designed correctly, a solid glass transom would be very strong, but also heavy. Hence we use cores to save weight. And money....

The a solid glass transom would in all reality end up lighter than a wood transom and the stringers out of glass also and be hollow NO CORES used and NO WOOD !! Just 100% fiberglass !

[Ramonepb]

Just watched you tube where Ranger is manufacturing with no wood. Very interesting how the build their solid glass transom and braces. Also the stringer system is all glass.

[tunnels]

Just watched you tube where Ranger is manufacturing with no wood. Very interesting how the build their solid glass transom and braces. Also the stringer system is all glass.

Interesting yes and the thought is there ! but what a disgusting mess ! If the splash well and bits that are attached to the transom are well thought out bracing such as knees etc are not necessary
That is not really a stringer as such its a two piece floor grid filled with foam and all that foam will soak water over time as always happens . Interesting yes and the basic idea is ok !, workmanship is highly questionable !!
See the hull is woven roving ?? so the boat will be heavy for sure !!

[Slimm]

Hi Ramonepb. I see you are in Winchester, I am in Lexington. I am not a professional builder but I do have a bit of experience working with fiberglass doing some car audio. If I can be of any help I'll be glad to ride your way.

Slimm

Just watched you tube where Ranger is manufacturing with no wood. Very interesting how the build their solid glass transom and braces. Also the stringer system is all glass.

[Ramonepb]

Tunnels
my thought is that all glass is great but foam puts you right back in the same boat. My belief is NOTHING is waterproof, water resistant maybe but sooner or later water will permeate everything.
just my belief. Wood is a capillary material designed to do so by nature. Sure if I built my transom from wood and do a good job it would outlast me! BUT I want to learn how to use glass structurally to make it light and strong enough for my goals,
1. Make it stronger than needed for the 115 that is on it.
2. Light weight to achieve my 60 mph goal
my boat does not have stringers or balsa core. Watching the glass hull flex in rough water I should not have been in was uncomfortable!

[Ramonepb]

Slimmdaddy
Where do you boat at? We like Cumberland but this boat is a little small for the big water. I have had this one on Cave Run which is close and will probably do some set up testing at the river at Boonsborough.

[tunnels]

Tunnels
my thought is that all glass is great but foam puts you right back in the same boat. My belief is NOTHING is waterproof, water resistant maybe but sooner or later water will permeate everything.
just my belief. Wood is a capillary material designed to do so by nature. Sure if I built my transom from wood and do a good job it would outlast me! BUT I want to learn how to use glass structurally to make it light and strong enough for my goals,
1. Make it stronger than needed for the 115 that is on it.
2. Light weight to achieve my 60 mph goal
my boat does not have stringers or balsa core. Watching the glass hull flex in rough water I should not have been in was uncomfortable!

The only mention of foam is for buoyancy inside the chambers each side and across the back on the ranger boats in the you tube video Its 2 part pour foam !
Wood is ok if you can seal it on all sides including the edges and when you drill holes for bolts etc the need to be sealed as well specially screw holes !!
When you say the hull bottom was flexing by how much was it moving up and down ! 1/4 inch ? 1/2 inch? 3/4 inch ?? how much ?? its always been doing it so why are you worried ?It means you are getting a softer ride !! what are you really worried about ??

[Ramonepb]

The flex was about a half inch. The. Boats I have owned I have never been able to see the hull. A baha sport 240 and the first boat I grew up with was a Hydrodyne and was solid and heavy as a rock!
i have also owned a 15 foot and 16 foot tunnels, but they were Okume wood.
Thanks for your input it is appreciated, if you have any suggestions or thoughts please post!
Jerry

[XstreamVking]

I can offer my opinion for a transom layup schedule. Motor side of trans, 1/4'' thick glass prefer bi-ply or matt/roving. Bond in a pc of 3/4'' core board. Add another 1/4'' of glass. Bi-ply is best. Bond in another 3/4'' core board pc. Cover with 1/4'' of glass. Adds up to 2 and 1/4'' thickness. (standard thickness) Run a beam made from 3/4' core board 3'' wide, the full width of the transom positioned between the motor mounting bolts. Glass this in with 2 layers of bi-ply. Here you have a composite trans that will be flex free and light. Plenty strong for heavy duty use with medium hp. If you want stronger, then make some fwd facing knees that go from the top of the transom, to the floor/stringers constructed from the same 3/4'' core board. Stringers from the same coreboard if needed. Coreboard should be 26# hi-density. Several mfgs. make good coreboard. Expect to pay 200+ bucks at least for a 3/4'' x 4'x8' sheet. Can do same with some good quality marine plywood. Will be cheaper, but heavier. Hope this helps....

[Ramonepb]

A big thanks! The stream in your posts, is that how you did it? It looks great and that is a monster Merc back there!
I am definitely printing your method.

[Slimm]

I hit the KY River in Frankfort and Lawrenceburg when I want to ride and get seat time, and I always take some time to fish. When I am hitting the largemouth hot spots hard I will hit Guist Creek Lake, Cedar Creek Lake and rarely Taylorsville. I have been wanting to ride and fish Cave Run for a while but everyone I mention it to tell me I'll hate it due to the skiers, jet skiers, wake boarders etc. I have set my mind on hitting Dale Hollow, Barkley, Kentucky Lake, Green River and Barren River.

I would have hit them already but the fishing at Cedar Creek Lake is so damn good it's hard to venture elsewhere. Maybe we can hook up and you can show me around Cave Run sometime?

Slimm

Slimmdaddy
Where do you boat at? We like Cumberland but this boat is a little small for the big water. I have had this one on Cave Run which is close and will probably do some set up testing at the river at Boonsborough.

[XstreamVking]

A big thanks! The stream in your posts, is that how you did it? It looks great and that is a monster Merc back there!
I am definitely printing your method.

My stream has a 3'' transom built with 3/4'' coosa 26# board. Floor is 12# 1/2'' board. Mine is a little stronger than I needed with the cross brace and the knees added. Not a creak or crack after many leaps and landings with a 3.0 merc on the back using a 4'' hyd jack plate. No alum plate on the inside either. If I can't break it, it is tough. I boat in salt water and ain't afraid to beat on it. I am confident this boat will easily out last anyone reading this....

[brocluno]

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This is the Kona. The tag on the transom says it was made in Westminster California.

Nice boat. I have almost the same hull with almost the same build-out plan. But we are definitely doing the Bubba Boat build version for the heck of it. We have other family boats with different workmanship

I see that they already "plated" the transom with a piece of aluminum diamond plate. That tells me the core is soft and maybe soggy... I have no beef with a transom plate. But need to go deeper and find out what's in there?

Does your transom inner face have a "strong-back" like a 2x2 glassed in across the face? What sort of work are you willing to take on? Split the hull and lift the deck so you can really get into the transom core?

So can you drill some access points into the transom core on the inside? I'd go about 2" out around the lower motor bolts for sure. Just drill through the glass and stop. Use an Ice Pick probe the core. Is it soft? Is it wet? Does it smell bad? If it's hard out 2" from the bolts it's salvable. If it's soft and/or soggy there, go out another 2" and try again. But 4" out is prolly a lost cause ...

If yes to wet and bad smelling you have to get the core out

If dry, but soft, you have options ... If soft only locally to the bolt holes, you can do a vacuum job with CPES and toughen the bolt hole area. You'll have to plate the inner face too to spread the load, but you still have a core out away from the bolt holes to absorb the loads and take fasteners

As to the floor, it's about what you want out of this in the end ... We are shooting for mile-o-minute. If you want more, you need a different approach.... We just pulled the soggy 1/2" plywood core floor. It was wet and not stinky (anaerobic decomp). We drilled a few holes along the top of the glassed-in stringer, just through the glass. Stringer is rock hard and no water

You'll be taking out the floor panel.I'd cut it out in strips with a skillsaw. Set the blade shallow. Do not cut into the hull or the core top. See if you can find the original tape edge for the factory floor lay-up. Once all that is clean, look at how the floor and the stringer meet the transom. That will give you ideas about how to tackle that and maybe how to get into the transom core if needed...

For the new floor we'll be using 3/8" High Density Overlay (HDO) which I have used on and off in boat work for over 30 years. It's all hardwood with a thermoset resin skin on each side. You've prolly seen it a million times w/o knowing it. It's used on highway billboards to make the flat face and in concrete forms, etc. It's stronger than regular plywood, has no voids, and if you seal the cut edges with CPES, it will not absorb water in any reasonable time-frame for a trailer boat. Because it has a skin on both sides it avoids what the MFG did not, a bottom side of raw exposed wood. I've had a sample wet in water for week with little absorption

Once the landing area is clean, and the board cut to pattern, you can bond it down with PL8X with a perimeter bead and one down the stringer. Or you can make up thickened epoxy and do a bead that way and set the board in place. Weight it down and leave it be. 24 hrs later start your floor fiberglass edge tape and lay-up over the HDO. I'd rough it with a 50 grit disk first, but epoxy or polyester resin bonds well to the skin.

It'll be tough and flat and a good composite compromise to a foam core structure (the lighter option for more speed). We'll be adding #10x2" SS square drive FH screws into the stringer on 10" centers. You don't have to, but I believe in double systems where possible. Bonded and mechanically fastened.

The floor/stringer/hull form a three surface double triangle (viewed in cross section) making them a double box beam to create rigidity and stop hull twist. The stronger this system is the better for rough water use.