Transom Thickness

saint056

Cadet
Joined
Jun 10, 2011
Messages
14
Does anyone know what the transom thickness is supposed to be on a 1982 Stingray 17 foot open bow with a Mercruiser Strendrive? I want to make sure I make it the correct thickness as the other wood was rotten and swollen. Thanks
 

rickryder

Commander
Joined
Jun 24, 2010
Messages
2,722
Re: Transom Thickness

Welcome to iboats and the Dry Dock!

2" - 2 1/4" I beleive is the thickness for your rig... What kind of damage are you looking at? Do you have some pics so we can help you to the proper repair. :)
 

saint056

Cadet
Joined
Jun 10, 2011
Messages
14
Re: Transom Thickness

I could send pics of the crumbled wood that was a transom at some point. I was just wondering if the thickness I was installing was the correct one. My new transom measure 1.90 inches and the bottom of the transom is .1875 inches. That still puts me at close to 2.25 inches with the inner glass I'm going to be installing. the old one was only 1.75 inches thick for the wood portion. But I thought that wasnt thick enough from reading other posts. But they were Alpha 1 outdrives and mine is a Mercruiser outdrive. Also, I've read that many boat manufacturers don't necessarily install exactly what Mercruiser advises. So if you say 2-2.5 inches is what the book says, I'm going with that. I'll send pics of the transom after the glue dries.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,953
Re: Transom Thickness

So if you say 2-2.5 inches is what the book says, I'm going with that.

Ayuh,.... 2.5" is to thick,... It's 2" to 2.25".... Closer to 2" is Better...

And it's got to be true, flat, 'n even, from top to bottom, side to side...
 

saint056

Cadet
Joined
Jun 10, 2011
Messages
14
Re: Transom Thickness

Ive been told that the manual says there is a 1/8 allowable tolerance from top to bottom. So you are saying that is not true?
 

saint056

Cadet
Joined
Jun 10, 2011
Messages
14
Re: Transom Thickness

Or maybe it was 1/16th? I'll have to check again. What does your manual say? Thanks.
 

rickryder

Commander
Joined
Jun 24, 2010
Messages
2,722
Re: Transom Thickness

Special Information
Transom Specifications
22170
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)
e - Transom Angle-10 to 16
f - Keel (If Equipped)-Remove 4 Ft. (1.2m) Forward To Transom

The flatter the better
 

oops!

Supreme Mariner
Joined
Oct 18, 2007
Messages
12,932
Re: Transom Thickness

this is kinda tricky......
the tolerance is 1/16th.

it is called flatness and parallelism.

what that means ....is around the key hole......it must be the same thickness from any point......that is parallelism.

the flatness means there cannot be any deviation from the parallelism from the inner face or the outer face.

but don't get too worried !......it is crucial, yes.....but at the same time...its no big deal......here is why !

when you remove your transom, take all the wood out, and grind the residual right to the glass hull.
(you will have grinding divots and high spots in the inner skin)

now....build your transom....
i like using a one inch ply and a 3/4 ply......the one inch is really nice to work with and is very stiff.laminate the two together with one layer of csm on each inner side.

after the transom is laminated and cut to shape....and you are ready to install.

use a thickened resin, and screed the stuff onto the skin of the hull.....use a trowel with a smooth edge. this will fill any gaps or un even surfaces left by the grinder.
then glass a single layer of csm on to the skin over the wet filler.

lay a single layer of csm on the inside of your new transom....and install the transom while all the resin is still wet.

you are now, very flat, parallel and darn close to 2 inches thick.

after the transom is in.....use your thickened resin, around the edges to fill any gaps.
tab the transom in with one layer oc csm around the edges over lapping the filler by 3 inches and 3 inches on to the hull.
on the bottom of the transom where the key hole is.....do not let this overlap touch where the key hole will be.
glass the entire surface of the new transom with 2 layers of csm.
each layer should be larger than the last, you also want to cover the tabbing on to the hull.

finally......a full 1708 covers the two csm. you can also use strips of 1708 to further tab a transom to the hull.

this process will give you 2 just over inches of glass and wood and will put you in tolerance range for the transom.

as long as your tabbing does not go into the area where the key hole is... your flatness will be maintained, as well, so will the parallelism!

in the link in my sig. there is a full transom install in an i/o situation. with instructions.

cheers
oops
 

saint056

Cadet
Joined
Jun 10, 2011
Messages
14
Re: Transom Thickness

Wow. Great advice. Thanks. I've also heard of people using polyurethane glue to adhere the transom to the hull. Any thoughts as to that technique?
 
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