Looking for a good deck sealant.

First post. I'm happy to be a member of this forum. I've been pulling information off this forum for a long time and now I'd like to share some to.

What's a good sealant that I can apply to my entire deck that'll fill in small holes and cracks? I'm going to add a layer of plywood to the existing deck because it's getting spongy. I'm looking for a quick fix to prolong the life of this old workboat for another year or two. I have no motivation to get into a deck rebuilding project. I just wanna make it a bit stronger and stop it from leaking.
I'm happy to give more info if needed.
Thanks guys.

 

ROOFING TAR ,

spread it with a notched trowel and screw the ply overlay into the beams below.Pre drill the ply so you know the beam locations

Paint the deck and on the last coat , while wet pour at least an inch of dry sand on.

When dry wash off the mostly unstuck sand and the finish will be no skid and uniform.

 

That's actually a very good idea. As strange as it sounded to me at first I'm thinking that'll work great. If it seals a roof for 10+ years, it's bound to seal a deck atleast two. Not to mention it's cheap and actually worked with it before.
Thanks Fred for the good advice.

 

Sand decks are a little too rough for my feet. An old time recipe I have used is to mix rocksalt into final coat of paint. Yes, the salt quickly washes away, but it leaves a foot friendly texture behind. It is also a lot less troublesome to remove for relocating.