How to plug a screw hole in a foam cored boat?

[gamayun]

Yes, good to do it right so you never have to do it again (in theory!). I use sealant as both a lubricant and to seal the head so water does not get trapped underneath. I think it's good practice no matter where you're doing this but if inside, then probably not necessary. As for the lubricant, you could also use synthetic grease instead. You just want to make sure that the screw does not bind. If it wants to stick as you're screwing it in (which is why you'll want to use a handheld screwdriver), stop and drill a slightly larger hole with a bit that's still smaller than the thread diameter. Calipers are your best friend here ...