Help with trim tab install?

[Nomo]

I'm installing Bennett trim tabs on the transom of my Lund Baron tinny. The hardware includes stainless steel screws for fiberglass boats, but the instructions say to use bolts with locking nuts when mounting the plates on aluminum boats. So that means cutting a chunk out of the rear of the deck and digging out flotation foam to access the space from the inside. Before I descend into that level of hell I was wondering if anyone had another solution. Would big pop rivets be too weak? Thanks for the input.

 

[Scott Danforth]

I wouldnt use pop rivets.

my suggestion would be a reinforcing nut plate posibly screwed and 5200'd on the outside if you cant get to the inside. However Tabman will be along shortly

do you have any pictures of the transom and the inside area of the deck?

 

[Watermann]

One option is to use closed end blind rivets on the lower tab mounts that are under the transom wood and back butter the mount with 3M 5200. 5200 is a powerful sealant and adhesive that once set will not leak or come loose. That's what I did for my tabs and have had no issues at all. The upper strut mount you can use the screws provided but I would also use the 5200 on those mounts as well for sealing and strength.

 

[fhhuber]

Or.... Drag stainless blind nuts into the transom using long all-thread
Once the blind nuts seat, you can remove the all thread and put in the stainless screws.

That way you can clear the needed amount of foam (far less) to clear the blind nuts with a long drill bit or a large "star" washer on the all thread and a shop vac.

This depends on straight line access from within appx 3 ft.

Its a modification on how I seat blind nuts in hard to reach places for other applications.

 

[Tabman]

While "officially" I should say dig out the foam and do it the way we recommend, I like Watermann's suggestions and that would likely be the way I would do it if it were my boat.

Does your boat have a small lip where the hull bottom extends past the transom like a lot of aluminum boats have? If so than you are going to need a spacer to extend the hinge plates out to it so that the lip will not interfere with the Tabs range of deflection.