I did my h34 for years ago.
Did a lot of research and layout for unit and ductwork.
The perfect unit I found was manufactured by mermaid
The M16 16000 btu unit fits perfectly underneath the larger seating area starboard side alongside the hot water heater. It's a tight fit but it will fit.
1) All the wires can be run from the main panel alongside the port water tank through the fiberglass cross beam which are hollow and then into the bildge and then up into the settee area to the unit.
2) Cut the air intake vent thru the side of the settee which will allow good air flow to the unit and also good access to the units air filter.
3) cut 6inch hole through the back wall of the sink cabinet to allow for the main ducting. Note you will have to sacrifice one of the chart tube holders.
4) run the 6 inch duct behind the sink plumbing to the cabinet shelf alongside the sink.
5) go to lowes and 5 get a transition junction box 12" X 12" plus qty of 5 round 4inch conector and 5 dampeners. And qty 1 round 6inch conector. Also get a 4x6 vent and 4x6 vent box.
Cut six inch round hole in the back of the transition junction box for the supply duct and four 4inch round holes for the four supply ducts and one 4inch round holes into the top of the transition junction box. You now have a total of five 4inch supplies now to run the ducting throughout the cabin.
6) run ductwork inside the cubbies underneath the plexiglass storage areas along the cabin. Three supply ducts have to feed the main cabin. run one of the three supply ducts to the corner of the bulkhead main cabin, the second mid ships of the cabin, and the third to the countertop alongside the sink. This will be sufficient to supply the main cabin.
7) supply number four needs to be run though the cabin bulkhead into and through the head shower cabinet. Then into the v berth starboard locker. This will supply the v berth with cool air however I found that the air supply was extremely weak due to the length of the run and had to install an inline duct fan to increase the cfm.
8) run the fifth supply duct behind the stove and into the aft starboard lazarette and cut a hole into the quarter berth bulkhead.
This should have another inline duct fan To increase the cfm.
Note that if you don't have three cabin supplies and one in the v berth along with one in the quarter berth the unit will ice up.
The unit needs to have more then enough supplies and the air filter needs to be clean at all times.
Also note that the unit takes up a lot of power from the main Ac panel. So budgeting your power use is critical, example hot water heater on with your air conditioner along with anything else will trip the breaker. I installed a second panel and shore power supply just for this unit.
This unit works really well, however on really hot and humid days it struggles. Keeps cabin comfortable but can't preform miracles.
Like someone else mentioned sunlight on the decks and no insulation on the boat, the unit can only do some much.
Overall I'm very happy with my unit.
If I could do it again I might want to install a smaller 5k unit in the aft lazarette to use on the really hot days so that the main unit would not have to work so hard.
Hopefully this helps.
