bertram31.com

Currently trim tabs are mounted to a solid piece of wood (2 x4 in the US) that is cracking and needs to be replaced.
The boat is a 79 and from what I have seen on other boats around that era they used what looks like plywood first then mounted the tab flange to it.
Unsure why the did this other than transom may not be thick enough to handle the load or didn’t want screws poking thru?
Only use the tabs a little when load is uneven or wind and waves kick up other than that boat rides great.
Maybe build up inside of transom or outside with marine plywood, glass or coosa?
Appreciate any suggestions thanks.
https://imgur.com/gallery/qyK3mk7

Jeff
My 28 is a 1983. They are mounted to the transom I don't remember what the inside looks like.

I mounted my tabs directly onto the transom, and on the inside I fitted a 2 x 2 piece of mahogany bedded in BoatLife to the inside of the transom and hull bottom. The backing piece is a little longer than the hinge on the tab.

They probably placed that spacer on the outside of the hull so the tab fit flat. Not sure on the 28, but the 31 transom has a curve to it. It was probably easier to figure out how to make the wood spacer sit flush than play with the Tab. You should be able to make it work without the spacer.

The B28's transom is relatively 'plumb' at the tab mounting areas, not 'cambered' as the B31...……….mounting backers of mahogany for the tabs and cylinder attachment to the transom sealed with epoxy/fiberglass resin and bedded to the transom with 5200 or Boatlife caulk would suffice so as to hold the tab and cylinder fasteners [I use screws for fastening of the tabs and cylinders to the transom, my theory being they would 'shear' out rather than nuts and bolts that would 'tear' out along with part of the transom in the event of any collision mishaps.....]

And looking at the tab photos Jeff those backers are probably 'glassed on to the transoms exterior and look to be in good condition? The 'cracking' looks more like shrinkage of the anti-fouling paint than degradation of the backers? Maybe a close inspection of the backers, removal of the tabs and a strip down and re-work of the backers [re-glass & paint] is all that's needed?

Jeff,

I have a 73 and mine were mounted on a 3/4" thick plastic spacer (starboard i think). Maybe to account for the slight curvature of the transom but not sure.

As Preston says, I would check the backers to ensure that they are properly glassed or sealed (preferably with epoxy). Wood expands/contracts in reaction to moisture, which can cause the paint to crack.


Regards,

Jorge