Installing Marine AC

[Craig Cook]

After reading over everyone's input on cooling our boat in the summer we have decided that the best way to go is to install actual marine AC. Although the most expensive option, I think in the long run it will be the least amount of hassle to get things cooled down and when we decide to sell the boat having AC will add value.
This will be a DYI project as there is no one within 100 miles that does such things. I am considering two locations, one is under the galley sink behind the electric cooler. There is ready access to the hull for the inlet and outlets plus it is close to the AC panel, it is also close to the aft cabin. The downside is that both the installation and later access to the unit for winterizing and maintenance will be difficult. The other option is under the V-berth. That area is wide open and we don't use the v-berth for anything but storage so noise will not be a factor. There is easy access to the hull but a long run to the AC panel as well as the aft cabin.
I was also looking at new vs lightly used units offered on eBay, any thoughts on that option?
Finally, if anyone has done this project are there any tips you can share? Pitfalls, cautions, anything I need to know.

 

[Gunni]

It won't fit into one of the settees?

 

[Craig Cook]

It will not. The settees are long enough and deep enough on the cabin side but have the curvature of the hull to deal with on the outboard side. I believe a level platform built inside one of those lockers would end up being too shallow. The locker of choice would be the one just forward of the galley. I don't have the exact measurements in front of me to quote numbers though.

 

[Justin_NSA]

FWIW, one of the POs of our boat installed ours under the V berth. There is a port and starboard vent on the v-berth bulkheads and the control panel is also on the stbd bulkhead. This is a heat pump type system, The freshwater pump is under the port settee. We don't have any other ducts. I sleep in the aft berth and it's very comfortable. It gets HOT in Kansas.

 

[Gunni]

Good point Justin. As long as we keep the cabin doors open I can cool and heat an entire 41 ft boat with a forward 12k BTU Cruiseair system. Pop some 12 vdc fans in the boat to make things even.

 

[Justin_NSA]

Good point Justin. As long as we keep the cabin doors open I can cool and heat an entire 41 ft boat with a forward 12k BTU Cruiseair system. Pop some 12 vdc fans in the boat to make things even.

Exactly Gunni. Mine is a Cruisair. I have a couple fans that circulate the air some.

 

[Justin_NSA]

Here is the starboard bulkhead showing a vent and the climate control panel. Excuse the mess. We also get heat with the system.

 

[JRacer]

Mine is also under the deck in the V Berth. While I often whine about the difficulty of doing work on it under there, standing on your head. The alternative is servicing it standing on your head under a sink or something similar. I would put it in the V Berth unless I had a good place that was easily accessible toward the stern. Only problem with mine is that there is not an easy way to duct it to the aft cabin. Ours is ducted into the salon and we use a fan to move the air aft. And Justin is right, we get HOT HOT HOT here. If I were installing a new unit it would be more BTU. Mine is a 12K BTU unit and I'd probably put in a 16K unit if/when I replace. But remember that we are often dealing with 100+ temperatures here.

 

[Craig Cook]

Hmmmm. Thanks for that photo Justin. I have been concentrating on the footprint of the unit and your photo brings up another important thing to consider, ducting. I researched the installation instructions on a few units last night and everyone suggests exactly what you have, an inlet of specific square inches located low, outlets located high. The low inlet would be somewhat of an issue under the v-berth because the fresh water tank is located in the locker just aft of the v-berth taking up the starboard 2/3rds. We could duct around that I suppose. The outlets are a whole other issue, high will not work anyplace on the boat, especially in the v-berth area. The forward bulkhead is more like a room divider, only about 3/4" thick. You could run a duct up on the forward side but that would look like crap and would require modifying the v-berth cushion. Mounting under the galley (about under the flowers) would solve inlet, power and water, but the outlets would be just a few feet off the deck at best. The builders pushed the settee cushions out to the sides of the hull for maximum room in the cabin, you can't run anything behind them.

 

[MitchM]

the residual heat from the 'electric cooler' might screw up the air exchange for the install. i'd go with the V berth option. the long AC electric run is not a big deal , ( you don't have the same voltage drop issues as with 12 v .) the raw water pump ends to be below water line submersed to work properly. the water pump is extra, get a god one like a technical not the cheap $90 unit made in china by certain other manufacturers. get a unit with reverse cycle heat too , for erie you'll need it. when you do the install, be sure to allow for access to do winter maintenance on the raw water pump that feeds your compressor and your filter into that pump. (winter maintenance is running some antifreeze through filter and pump , cleaning the filter and and then loosening the face plate screws. if you have room, put in a T with a slew on cap after the pump and before the compressor allowing you to easily bleed the system . on a sailboat, sometimes the raw water Air Con pump loses prime when you're heeled even if you sail with AC inlet seacock closed- ( don't ask me why.) don't expect the 12K compressor to blow cold air through a duct from v berth to a ft berth . though MarineAirr and CruisAirrr do offer a duct splitters off the compressor for this purpose you get 1/2 the air flow into the v berth area by splitting it. such a spot duct system does a poor job IMHO of cooling 2 areas. we had a spot duct system on our 30 , i ended up ripping it out and converting to a single duct serving only the v berth . that system worked great to cool the whole 30 foot boat as long as you did n't sleep with v berth door shut. (if anyone wants a duct splitter for a 10K MareinAirr system just PM me. )

 

[Craig Cook]

Wow, that's a bunch of really good information Mitch, thanks. I spent the weekend doing additional research, this is getting more complicated by the minute. The design of the AC breaker panel is unusual, there is not a traditional panel so I can't add a breaker. I will need to wire in a whole new panel plus do the run to the AC unit. I also need to get a better idea of the depth of the locker under the v-berth and where the thru hull for the intake would go. Looks like this coming weekend is going to be spent measuring down at the boat.
Interesting thought on the heat from the cooler, I never considered that.

 

[Pat]

Our O'Day 272 had very few places we could put the compressor and such so after pondering it for several weeks and doing
drawings for this and that, I decided to put the compressor under the V-Berth....I've been thankful I made that decision....I installed a 12,000 btu Mermaid and everything I did was done after discussing the various options w/ the Mermaid folks in
Florida....It has been a gem.....I stalled 4 inch flexible. ducts...that is maybe the only thing I would do differently....i.e. I think I would use smooth duct as it eliminates disruption of the air-flow thru the ducts....the compressor fit perfectly in the little standing area (which I didn't use) when the v-berth insert is removed....The pres. of Mermaid was nice enough to call the folks at O'Day to verify that I could use the already installed water supply thru-hull for the head....works great and eliminated separate thru hull being installed for the AC...does not at affect the water available at the PHII head.....installing ducts was by far the most difficult part of the installation as I was in no way going to tamper with the awarthship stringers running port to starboard in the bilges as I believed than as I do now, that they provide strength to the hull...not cutting them meant I had to go up with my ducts...so I drew something up...sent it to Mermaid and they answered back almost immediately that what I had drawn would work like a champ....so that is what we did... A good friend at our club helped me do the installation and he and I agreed on every facet of the installation....Your's will likely be different, but this thing is quiet and keeps the boat really cool at night at the slips.. the 12,000 btu unit should have been a 16,000 in hindsight, but who wants to sit below using the AC at 2:00 p.m. in the daylight.. The culprit to the size variation is the quarter berth is big and holds heat built up all day...a bimini would solve this as would an exhaust vent back there......All and all, I would not trade it.....after the fact, I did install a 200
c.f.m. in line duct fan right at the blower exit point from the compressor....is hidden, is quiet and really amped up the air
velocity (cfm) of the entire installation....one of the best things I did....it powers up every duct...There are 3 ducts...One to v-berth and two to main salon...Good luck, Patrick in cold Wichita...sorry if I rambled.

 

[IH82BL8]

Installed a Webasto FCF 16k BTU in our Hunter 31. It's a very quiet unit, so no noise to worry about. I bought the install kit, too. Include raw water strainer, pump, hoses, clamps, duct and vents. I winterize mine at the raw water strainer, don't need access to the unit itself for that.

 

[taylor ward]

Installed a Webasto FCF 16k BTU in our Hunter 31. It's a very quiet unit, so no noise to worry about. I bought the install kit, too. Include raw water strainer, pump, hoses, clamps, duct and vents. I winterize mine at the raw water strainer, don't need access to the unit itself for that.

Where did you install the ac unit on your hunter. I have a 31 1984 hunter
thanks
taylor

 

[IH82BL8]

Port side, dinette, under the aft seat just forward of the galley.