> I don't think I'd trust anything short of epoxy for real waterproofness.
> West Systems makes a "5 minute epoxy" which does need to be
> mixed but uses a forgiving 1 to 1 mixture ratio...very easy to eyeball
> small batches for spot fixes. I've used it for small "fixes"
> here and there and been happy with it. (I'm not sure of the price, but
> it's fairly cheap.)

Actually epoxy is not considered truly waterproof, but is generally good enough. 5 minute, 1:1 mixes are generally less waterproof than the other mixes. Don't use a hardware store type 5-minute, they are not very waterproof. The epoxy itself usually does not fail, but the bond between the wood and the glue.

Thinner epoxies hold up in water better due to better penetration into the wood.