Under aft berth
I have an 88 Cat 30 with a tall rig. The prior owner installed the a/c unit under the aft berth. It's easily accessible through the top of the berth. The raw water intake is just aft of the engine with a bleeder valve set into the intake line. (Makes winterizing a snap and bleeding out any air locks.) I'd think that you could use the same through hull opening for the raw water intake for the engine. Unless you're using a generator, my a/c is for dock side use only and is never run when the engine is running. Thus, no competition for the raw water source through one intake. The main air return vent is located on the port side of the aft berth, just under the cockpit. My boat has only two cold air outlets. One is at the end of the aft berth where your feet go and the other is just over the ice box in the galley. All of these spaces were easily accessible for running duct work. My unit also has a heat pump so I can a/c or heat the boat. I've had no trouble getting warm or cool air forward into the v-berth. A small fan located on my starboard hanging locker moves the cool air forward. A friend who has a standard rig Cat 30 ran his duct work under the starborad settee and behind the hanging locker so that he actually has one air vent facing aft on the forward bulkhead and another blowing directly into the v-berth. His unit is also located under the aft berth. Here in TX we experience 100 plus degree weather on a regular basis and these units work great.
