Norminn wrote:

I tried spar varnish only once, and found it very thick and difficult to
brush out. I've used other varnishes countless times, and spar may be
different than what I experienced. The OP seems pretty unfamiliar with
wood finishing, so tips need to be made with that in mind.

I don't think I have ever varnished anything before.

moisture seepage needs to be sealed out.

The door will get soaking wet from rain so this is important!

Power sanders may be overkill for someone without some experience.

I have a Makita belt sander but I can not imagine using it on this
door due to the ins and outs of the molding. I might use it on the
sill but even then it might dig a huge hole before I know it.
I am ok with hand sanding though.

I suspect I start with the heavy grit. And then down to fine.
What is the heavy grit I should start from?
Wikipeidia has a list http://en.wikipedia.org/wiki/Sandpaper

Does P50 look like a good starting point?
And maybe P220 as the final grit on the bare wood?