First time replacing transom wood

[silvert]

Hello everyone. I have a '99 Rinker 232 open bow that I bought a few months ago for a project. Had a cracked 5.7. Removed engine, also removed transom assembly to replace the gimble ring that had some slop in it. Rebuilt the transom assembly, went to torque it back into place , and the transom plate cracked way before getting to the specd 25ftlbs. After some investigation, I found that the 2 bottom holes in the transom had soft wood all around them. The wood compressed when torquing the plate, causing the plate to bind and then crack.
So far, I made a template of the wood, removed the wood, going to pick up some marine plywood today. Plan on using a place out west called Aeromarineproducts for my fiberglass supplies. Hope to order it all today.
A few things I found that Rinker did. First, they only tabbed the transom in with fiberglass. after about 4 inches, the wood was just painted. The wood does not go to the stringers. Stops a few inches before stringers. I'm lucky here I guess. Next is they did not attempt to protect the bottom of the wood in the bilge area. All it would take is 2 inches or less of water, and the wood was exposed. the rot started here and leached up to the bottom holes of the transom. Great work guys lol.
I plan to fiberglass all the wood. Any and all suggestions are welcome. I've done hours and hours of research here and watched all of friscoboaters videos.

Here is the bottom of the transom wood.

Another pic to show the relation to the drain and all

Wood removed

Thickness of the hull is right at .700"


Original thickness of the wood and hull was 1.73". I've seen that mercruiser wants 1.75" to 2". I plan on being closer to the 2" by going with 1" of plywood, the .7" off hull and then a couple layers if fiberglass.

Wish me luck!

 

[silvert]

By the way, this boat came from mid ohio. Never seen saltwater, was never kept on the water. Sat under a shelter. Has 500 hours on it. Would have never imagined it would have had transom issues.

 

[Woodonglass]

While you're at it, I'd recommend core sampling the motor mounts and stringers to ensure they haven't been compromised as well.

 

[silvert]

I drilled a few 1/4" holes and it all looked good

 

[Bondo]

Ayuh,.... Merc wants 2",..... the Spec is 2" to 2, 1/4",....

 

[silvert]

Got some marine plywood, and cut it to fit. This is 2 pieces of 1/2". Need to glue it all together still.

That place I was hoping to get my fiberglass supplies from is not very good at returning calls. Any suggestions on places to go?

 

[Woodonglass]

Where are you located? I'd recommend rounding the corners of your transom wood and also grinding the areas on the side areas of the transom and the bottom of the hull. I'd recommend tabbing the transom wood all the way around the edges when you install it. You can glue the two plywood pieces together with Gorilla Glue or TiteBond III Wood Glue. Both will do the job really well.

 

[silvert]

I'm in the Cincinnati, Ohio area.

Thanks for the input! Will the gorrila glue also bond the plywood to the hull?
I'm starting to get the game plan. I will round all the edges, use a "peanut butter" mixture to fill in. I guess the grinding will make it so the tabbing of the fiberglass will bond better?
I will use 1708 for the tabbing and covering of the wood. then it looks like a cop strand to cover it all.

 

[Woodonglass]

You should do a lot of research a reading here on the forum. It's ALL here! You will see and read all about exactly how to install your wood transom in your boat. Friscoboater does a good job of it but there are many many others too.

 

[Woodonglass]

You should use PB to glue the transom to the outer skin. Read this...Fabricating Decks, Stringers, and Transoms.

Here's a sample Pic of what a finished transom looks like tabbed into the boat, before the Keyhole is cut out. Notice how the glass is wrapped around the edges of the wood and out onto the sides of the hull and onto the bottom as well. If all you are doing is that transom then I'd think all you'll need is about 3 gallons of Polyester Resin, 2 Yards of 50" 1708 Fabric, 10qts of Cabosil. I'd recommend U S C O M P O S I T E S . C O M

Like Bondo says, It's CRITICAL that you get your transom back to a minimum of 2" thick and it must be Flat and Parallel in order for the Outdrive to mount and seal properly!!

 

[Bondo]

Ayuh,.... I use one of these to redrill the holes,.....

 

[silvert]

Thanks. Ordered all my supplies.

What I dont understand is why the factory transom was only 1.75"?

 

[jbcurt00]

Is that 1 3/4" including the 'horse collar' that's usually right at the outdrive? A small ring of 3/8" ply?

 

[silvert]

Yes 1 3/4" total. Here is the measurement of the wood
you can see it is just shy of 1". There was no fiberglass skin at the hole, it was just tabbed in. You see my pic in a post above that the hull is .700". Had a guy on a rinker Facebook page that said he used to work there say mercruiser wants 1.75 to 2". Everywhere else I read says 2 -2.25. I am shooting for 2 just to be safe

 

[silvert]

Picture of the boat as it sits in my garage. I think it's a great looking boat. hopefully will be out on the water very soon. Have a new engine waiting to go back in

 

[Woodonglass]

Well, I'm going to advise you again to install your new transom with PB glue, and 1708 tabbings and 2 full layers of 1708 fabric. I think I'd make the transom from 3/4" and 5/8" ply wood. That would give you close to 2" transom once it's all glassed in. I really wouldn't want it to be under 2" in thickness. Regardless of what it was previously. Merc' Specs are published and there to be followed. I haven't heard of too many people not following what the factory says to do. And as I state earlier it is very critical that the keyhole area be flat and parallel and the thickness tolerance is all the same so the gimbal ring mounts perfectly and everything will seal correctly.

 

[silvert]

I plan on using pb to attach it, tabbing it and a few layers of 1708. I have 15/32" marune plywood I just bought. Maybe do three layers? I really don't want to go back and buy 2 more sheets at $70 each. I do have enough to make a third layer though. That would get me 1.41" of plywood and then another .700" for the hull Making it 2.11" before the fiberglass. How thick is two layers of 1708? Is it bad to have 3 layers of plywood? Or do I go with what I have at .700 (hull) + .940" (plywood) + thickness of 1708 whatever that is. This would be about the same thickness the factory used.
I'm as confused as ever now. I would imagine that the manufacturer set it up correctly?

 

[Woodonglass]

Ok , Kool!!!! I thought you were going with a 1" core. If you build it as described you'll be absolutely fine!! 3 layers will be Strong!!! You should finish right @ 2.25". Is your outer skin flat and uniform in thickness all around the keyhole?

 

[silvert]

Took my micrometer around the transom hole. Highest was about .730 and the lowest was .620.
What kind of tolerance do they recommend to be parrallel? The lower numbers were on the top of the hole and higher number down low.

 

[Woodonglass]

Here ya go...


Transom Specifications

a - Transom Thickness-to Be 2 In. (51 mm) Minimum To 2-1/4 in. (57 mm) Maximum
b - Transom Surfaces-MUST BE Parallel Within 1/8 in. (3.2 mm) Measured At Top And Bottom Of Cutout Hole
c - Area Covered By Inner Transom Plate-MUST BE Flat Within 1/8 in. (3.2 mm)
d - Area Covered By Gimbal Housing Assembly-MUST BE Flat Within 1/16 in. (1.6 mm)