Filling in bolt holes?

I'm being asked to fill in the bolt holes left behind when a Scotty 241 mount was removed.

I believe they're 3/16th inch in diameter bolts.

Would using a plastic welder and welding rods be the best way, or is there another method of filling them (and making them look nice when I'm done)?

I expect I'll only need to do anything like this once.

I used stainless steel round head screws, with a washer and rounded nut.

After I used metal, I saw plastic hole plugs.

I've used plastic (nylon) screws. get a size that will thread themselves into the hole. Screw in with some sort of sealant on the threads then cut the tops off flush with the surface.

Interesting fix - and cheap too!  Thanks for the tip.

I've used plastic (nylon) screws. get a size that will thread themselves into the hole. Screw in with some sort of sealant on the threads then cut the tops off flush with the surface.

You could probably get away with plastic body panel rivets too, just coat with sealant and push into place. I use silicon caulk or rvt when  sealing fittings.

Thanks, Speedy.  This is my kid's kayak and I'm sure she'll insist I make it "look pretty".  The rivets would be fine for me because I'm not as totally anal about stuff as some people I'm related to.  I'm pretty sure I still have some of those rivets out in the garage.  Now I know why I kept them.

You could probably get away with plastic body panel rivets too, just coat with sealant and push into place. I use silicon caulk or rvt when  sealing fittings.

Any correct sized bolt with a dap of silicone will work.  Stainless bolt if you don’t want it to rust over time. 

Any correct sized bolt with a dap of silicone will work.  Stainless bolt if you don’t want it to rust over time.

IMHO, a stainless bolt with silicone or goop is definitely the way to go. It’ll never leak, and if you ever want to install something, it’s easy to re-open the holes. This works (with fender washers) for larger holes too.

You can also use well nuts. They come in different sizes

It seems that, if I'm lucky, the Scotty surface mount might have a Scotty backing plate, and all I'll need to do is remove the mount, then tighten the bolts back into that plate - with a bit of Goop for a good seal.

Simple and not a lot of fussing-around - just the way I like it.

Thank you all.