Interesting what Dave is saying, but most A/C units I have seen had baffles after the cooling battery to try and strip droplets of water out of the air flow. Regarding balancing the the recirculation, I have usually set this up with the Fresh Air Damper 100% open, and the recirculation damper open 100% then, assuming that the ship is properly "battened down" for A/C operation, any air not drawn out by the various exhaust / extraction fans will create a positive pressure in the accommodation and push back into the A/C fan suction in preference to fresh air from outside. The system should be self regulating automatically drawing in enough fresh air to replace any drawn out by the exhaust fans. It was my understanding the recirculating % is determined by the capacity of the exhaust fans compared to the supply fans. This has of course changed over the years, I think at one time 80% air re circulation was acceptable, I think it is only 40% now, that is another thing to check in SOLAS, which also lays down the number of air changes per hour in in each type of space, and special rules for Hospitals and smoking areas etc.
Obviously all external doors and windows have to be kept sealed for the A/C to be effective, The main role of the A/C is to strip out water from out of the air and condensing all that steam takes a lot of power, recirculated air from the accommodation has a lower humidity and therefore takes less power to cool down enabling a lower air temperature to be achieved with a lower power consumption.
I think that most Naval ships, built in the last 20 or 30 years have chilled water systems to cool their electronics, the same way as Diesel Electric ships do, with water cooled propulsion motors, Alternators, rectifiers and inverters.
Hope some more people can add their thoughts on thsi, Refrigeration and A?C are not well understood at Sea, and a good discussion on this would be very beneficial to all our readers.
It is always better to ask a stupid question than to do a stupid thing.