I haven't tried it (and cant see why you cannot), but cannot see why you would.....

I am curious to what you are thinking for wanting to wet sand varnish......


EDIT: I think I may be on a different page then you

Toph said..
Have a read of this if you haven't already done so www.antiquerestorers.com/Articles/SAL/rub.htm

Having read this, I realised it is a finish I have done (on a homemade coffee table). It was a long, tedious process that looked great when finished. I am not sure if I would put the time and effort in for exterior use. It would look a treat, but I don't think it would make the varnish last any longer.

Have a good read of the link above. It does make mention that standard varnish is hard to rub.....

Because the brush marks in the interior timber work are a discrace! The timber is a real show piece. As I will be living aboard I do not want dust and crap going everywhere so if I could sand it wet I could do a section at a time with out making dust.

So you are are rubbing the interior... I was asuming you where doing the outside...
In that case, it would still be a long and tedious process that would would be worth the time and effort

just the interior Toph .....a few beers over a few nights with a bucket of 120 grit wet rub should do the trick! The only Timber on deck is a teak toe rail....have not been a fan of teak but the quality of workmanship is superior so I will just have to deal with it!

If you look at the saloon table you will see what I'm talking about. Maybe it was just my first impressions but I guess at the end of the day I'm a perfectionist and I need the finest finishes possible.

It depends on what finish you desire....120 grit is pretty coarse, good for flattening the surface, but the end result will be a matt finish.

if you are looking for high gloss 120 to flatten, 400 then 800-1200....then car polish.

or if varnish is good, just a bit dull - skip all the sandpaper... just a cutting polish.

I would do a test with polish first, if it gives required result... it won't damage much. Starting with sandpaper, and not getting required result means there not much varnish cover left.