Used one on my H31...
here in Annapolis. It struggled in the mid-day heat, but otherwise did ok. I used a small clip on fan on the forward bulkhead to push the cool air on back. No sure how you'd get it into the aft cabin on the 310.I've written this before, but for just a little more money you can get the perm install Mermaid, Marine-Air, etc. I now have that type in my 37.5. If you handy, you can probably install it yourself. You will be FAR happier with the perm install unit. Those port cruise-air units are way over priced and are heavy to move off/on/around the boat.Or, just set a small window unit in the companionway when you want cool air. Easier to move around that the CA unit, cools as well if not better. You can get them for $99.