I donít see the gain in trying to get away with the smallest AC you can.
If you oversized a bit, you can run it in low, which is usually less noisy, and if you wait and decide itís just too hot, Iím turning on the AC, then youíll likely have success cooling
down an already hot boat, but if your AC is just big enough, itís going to get cool about 10 PM at night, cause itís just enough to maintain cool, but not enough to remove all the excess heat from an already overheated boat.
Think about it, if itís already hot, you have to absorb all the excess heat from all the interior furnishings etc., before you really begin to cool the boat.
Multiple, independent units are best I think, because the are less expensive for each, if one goes bad, real easy to replace and you donít break the bank, plus you still have the others to stay cool with, and you only have to run the ones you need to, not cool the portion of the boat that doesnít need it.
We arenít a Cat, but I can run the little one in our stateroom, a 6K off of just a little Honda generator in eco mode. It keeps us cool for sleeping, but we rarely use it.
To run the 16k and the 6K requires the Diesel