When I silconed the 1st board in, found didnt stay well attched.. moment, sun etc..
And I siliconed in lines...this caused even thu didnt sit right down, mould, alge growth under and around the edges..
Sorted to some extent with a spray on gone in 30 sec alage spray.
Then next attempt was countersunk screw washers.. all good.. better gap to wash out with power hose nozzle.. and the gone in 30 to back up
Down side of that is I knew where the counter sunk screw heads $ where unde the bait fish, but others didnt..
Result the cutting top end of the bait knives not just got blunt but rounded / broken off, and took a lot to get that well used section of the blades back before each trip out
So now it self tapping screws from up under the bait board into the ply / plastic (personal choice) .. thru the insert. Then remove , and cut so the tips of the screws dont go all the way thru... 4 of them... and better cleaning , flushing underneath.
Then later added the draws.. best thing since sliced bread..now 8 screws that also hold them up and 2 in the middle