Sport Nautique Teak Swim Platform

[Backwashphili]

G‘day!

I’m currently remodeling our wooden swim platform and was hoping for your inputs:

- What kind of glue should I use to glue together the underlying stringer and the wooden top so that I will get an air and water tight composite. Looks like a black kind of silicone has been used by the previous owner.

- Some wooden planks from the top layer look a bit rotten from the underside where the stringer was, is there some kind of treatment I should apply before putting it back together?

- I didn’t want to sand it off too much as the whole platform should stay as strong as possible.

Thanks for your inputs,
Phil