I have tried both a window unit rigged for the companion way and a floor model vented to a portlight and I preferred the floor model because it was a more powerful unit and it cooled very quickly. The floor model is on wheels, so I could roll it next to the mast and bungee strap it fairly securely. The window unit was awkward to step over all of the time and I did try to rig it for an overhead hatch but it seemed to loose a little power.
Here's the floor model:
http://audraswholesaleoutlet.com/store/ ... Path=34_22After discovering the joys of air conditioning when it's 95 degrees outside and no wind, I broke down and installed a central heating/air conditioning system so I don't have to worry about hassling with a portable and storing it. Love it so far!