seam sealing

On my current and first boat build (aluminum). I am learning how much aluminum can warp and how good fit-up needs to be to prevent blow out. Since I'm hand cutting these pieces fit up isn't perfect and I'm already designing work arounds for my next build to "hide" imperfect fitment. The original...

I have to seal two beam socket holes and need a sealant for above WL. I am considering dolphonite or slickseam. Others? there are only two sides for the bond and no backer; the seam is a little bit uneven; not measured, but somewhere around 0.100". tia I thought I posted this question...