Mounting Stainless Steel Plate on Transom

[PhilDuhs]

Hi,

I will be bolting 2 stainless steel plates to the transom of my fibreglass boat into which I'll slot Weaver snap davits (see Weaver Industries, Inc.: TRANSOM MOUNT DAVIT HEADS FOR INFLATABLE DINGHIES) when I want to raise the tender out of the water for sailing. I have had the plates made in 316 stainless steel (as per the attached picture which was taken part way through the process prior to polishing, etc) and now I'm wanting suggestions for the best way to fix them to the transom of the boat.

Of course they'll be bolted but I'm not sure whether I should have some layer of silicon/other material between the plate and the gel coat or just to bolt them on as-is. The plates are not 100% perfectly flat (although they're pretty good) so an intermediary layer might also reduce pressure-points, etc. It would also prevent any water ingress around the bolt holes...

Is silicon a good material to use? Should I let it "set" before fixing the plates to the boat? Is there some better material? Whatever I use, I want to avoid it compressing later and the plates becoming loose if possible.

Suggestions welcomed.

Rgds,
Phil

[Lancerbye]

I would use a compound like Sikaflex which will also act like an adhesive. Better than silicone. attach the plate without tighten it down too tight until the compound cures. It cures like a rubber and can be painted. There are various types for under water or above water and UV resistant. I don't find silicone seal a good compound to use on a boat.

[timj]

Agree with Sikaflex. We use Sikaflex 261 which is far superior to any silicon.

Generally there is no good application for silicon on the boat.

[kali]

The better solution is butyl tape.

http://m.youtube.com/watch?v=4Upksj19lyU

Karl