You might try to fab a stainless cover plate that will fit with much less clearance.
Maybe one of wood that sheds the water away from the flat stock.
Then use clear silicone to seal the smaller gap.
I use silicone and the boat has not leaked there for 5 years.
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
I am not a prejudice racist sexist bigot. I just hate stupid people.