I'm looking at endless Youtube videos for modifications. I ordered some decks eyes to be able to customize as I want, but what's best? Rivets or screws? I've seen both. Screws seem easier, but rivets may last longer and stay more secure. If using screws, do you add some type of silicone or marine sealant?

I'm not even sure if I'll add any (pick up my kayak on Sunday) but I'm looking forward to making some modifications (within reason).

Just curious to see what the consensus is.

Thanks!

If you can reach the back then stainless screw and nut. If you can't access the back the a tri grip rivet.
If it's load bearing and needs backing look up the " yak attack rigging bullet"

screws. alà Rob.  I'd use a drop of goop too, and wipe up excess if you have to.

Bushy

If you have access from the bottom, screws and goo. If not, rivets and goo.

If you have access from the bottom, use bolts, nuts, and fender washers with goo.  In not, screws or rivets and goo.

If using rivets, always use Blind rivets, similar to standard rivets except that the mandrel is completely enclosed. The result is that the blind rivets are water tight. Example:

      We're talking a good 3/8" of grip range  is needed to attach something like a padeye to a kayak...   That's why we use the tri-fold style rivet.  They also spread out wide preventing pull out.   They come rated for pull strength... but all the ones you see sold for kayaks are usually the same.
     Water intrusion is small through most rivets.   A small dab of sealant applied to the top will help seal it....  never use a rivet at or below the waterline.
     Always best  if you can get a screw / with a backer washer / nut as the fastener...  Rivets make it fast and easy.

screws. alà Rob.  I'd use a drop of goop too, and wipe up excess if you have to.

Bushy

This, plus fender washers.