: I am about ready to coat my kayak, and am trying to find a good product that
: I can pick up locally. I've been searching the archives and see that Zar
: seems to be highly popular. However, I searched the manufacturer's site
: and it looks like there are no suppliers in my area.

Check local paint stores and independent hardware stores. The list on Zar's site may not include businesses that buy it through distributors.

: What are some other good oil based exterior polyurethanes? I am trying to
: finish up the boat in the next week so I can take it with me when I travel
: the following week.

I've tried a couple of others, such as Helmsman, but Zar is considerably better and I won't use anything else.

: Also, if I don't let it cure till its totally hard (for better cohesion with
: the next coat), do I need to sand between coats?

Follow the manufacturer's recommended re-coat times. If you don't allow it to cure properly between coats, it will take forever to cure. This happens because when you coat over uncured varnish, the new coat blocks oxygen from getting to the previous coat, preventing it from curing properly. The more coats you add, the bigger the problem and the slower everything will cure. You cannot rush a varnish finish.