Input on Cabin A/C
 

I'm finishing up my cabin and cockpit upholstery on my scarab flatdeck project and am seriously considering cabin A/C (wife, kids, grandkids etc.:)) I wouldn't consider it but I'm liking this DC powered unit (comes with an inverter). I'd have to run a water inlet from the engine room with probably a pressure regulator, and drain out the sink drain on the port side (don't want any more holes in the hull). This unit is 6000btu but looks like it's more than up to the task. It would be an extra 61lbs not counting any of the plumbing etc.

Am I missing something? Thoughts? Ideas?

Here's the unit..

https://citimarinestore.com/en/ctm-m...er-21601c.html

Wow, i haven't seen this one yet but we are actually working with City Marine specking one of our pumps for his systems.
It doesn't say if there's a pump included with that system or not...it says they recommend a 250gph pump...that places it in our series 2...most common is the LC-2CP-MD
Only thing to keep in mind is battery capacity. Not sure how long you want to be out on the water running the AC on battery power...but you would need to size battery's according to that...

Does your Scarab already have shore power? I'm not quite sure why it's listed as 12v when it actually requires 115v. That's a lot of money for it to run off of an inverter - and it will kill the house battery bank unless its huge (not really possible in an offshore performance boat).

https://www.marinaire.com/Marine-air...-p/msba6k2.htm

Add your pump and ductwork, and a generator (Honda 2k works great) and you'd be set.

I love my AC on my 37 AT and would add it if it wasn't already there. My 30' Panther was not necessary.
I don't understand how that 12V AC would work. I have a AC on a cruiser that can run off 4 1275 Trojan golf cart batteries inverted and that doesn't last long. Shore power or AC/DC would be the only way to go.

Sorry I wasn't clear, I was planning on only using this unit when the engines were running and underway or when plugged into shore power. I wouldn't run it any other time as I'm sure the batteries would be killed pretty quickly. Guess I need to do more research to see if my alternators would be up to the task? I don't want the added weight of a generator or more batteries. If this wouldn't work my passengers would just have to sweat. I want this to be a fast slow boat lol

I had a 5000btu 120v ac unit on my boat. A grp 27 battery would last 2 hrs using an inverter on it.

The holy grail in the marine AC systems is to run in 12v DC only.....only way to do it so far is to run on an inverter....so its still technically a 115v AC system. But they are doing some cool stuff getting closer to make it a reality....battery capacity will always be the limiting factor of this kind of system...
The only thing thats trowing me on the specs of the one you posted is the current consumption f the inverter...it says 38.5Amps but the inverter only has a 15amp fuse???
the AC unit itself is drawing a max of 4.5Amps when cooling and our little pump would be pulling about 1amp at full output...so they system should only be pulling under 6 amps total which is not much....so depending on the inverter you could run for decent amount of time on the batteries.

running it while underway? depending on how fast your running you may be asking for problems. I had a guy once call me cause they were blowing the cooling tube seals out on our pump on his outerlimits when they ran over 80mph! LOL
he solved his issue with a solid sea strainer and a pressure relief valve for any pressure spikes when they launched and re-entered. Also make sure the inlet for the AC system has a scoop type thru-hull. If its flat to the bottom it may siphon the liquid out of the AC system as your running and water is going past the opening. Alot of sail boats have that problem too :D

Yeah I'm dealing with water pressure problems currently and have water pressure gauges at the helm so I keep an eye on the pressure to my motors. I have the transom mounted pickups, and have been slowly trimming them to hopefully get the pressure manageable at higher speeds. My friend with a 42 cigarette has pressure regulators for his motors and I may have to go that route for the motors as well as the a/c if I purchase this unit. Like you said 12 volt dc is the holy grail of boat a/c, you'd think somebody would have figured it out and made it easier by now.

Why underway? The wind isn`t enough??? plus theres this thing called water all around the boat you can cool off in .lol
Forget that idea , you`ll never use it and it won`t work that way anyway.
Right way to do it is a seperate pick up , strainer or plumb into current strainer while at the dock, and while at the dock you have shore power so you can get a unit thats half the cost and without all that extra bull$hit.Converters and all that

I can give you double for probably less. Have her cutting glass in no time. https://www.offshoreonly.com/forums/...u-%241200.html

at least it`s a ton of cooling ... 6,000btu is pretty wimpy, if its too small for the space it`ll freeze up.

6k but will cool your cabin, but you'll need to cool it the night before to get the humidity out. If you keep the cabin door open much during the day it really won't keep up.
10k would be my vote.
BUT if you don't run a generator, you are stick with the 5k or 6k size. You'll need to upgrade your engine alternators to 100Amp minimum.
A 6k AC will require about 1300 watts when running but will surge over 2200 watts on startup.
1300 watts from 12v is 108 amps. Factor in 20% inverter loss, and you're up to 135 amps of running current.
Your engines and trim motors will pull about average 15 amps per side while underway (30A, taking you up to 165A.
Your interior lighting and stereo load can run as much as 50 amps which puts you at 215 amps of "running draw" on your batteries.
If you run a fridge, then that's another 7 to 10 amps of DC.
SO cruising down the lake at 50mph occasionally adjusting tabs and drive angles, listening to"yacht rock" at medium high thumping volumes with the kids at 68 degrees playing Scrabble inside and a fridge full of cold YooHoo you will be pulling 200+ amps from your battery bank and refilling them with whatever your combined alternator output is.

Each full size battery is 90amp-hrs.eans it will provide 90 amps for an hour, or 45 amps for two hours, etc.

If you run 3 batteries, you should isolate one to be used ONLY for engines and trim. That leaves 3 (180 amp hours) for your other goodies.

So if you have 180 amp hours, two 100 amp alternators, and a 225 amp LOAD... then you have a NET loss of 25amps. Running nonstop at cruise speed, you have SEVEN hours before you have 3 dead batteries.
At anchor, assuming you start off with two hot batteries, then you have ONE hour of tunes and AC before they are dead.

Adding batteries is 1/2 hour per battery at full AC, interior lights, and stereo.

This is why people buy generators.

I had a water-cooling-converted window AC unit, 6k btu that I was going to use in my 311. Ended up getting rid of it because the carry-on Cruise Aire that I have is just easier to use - just put it up on the deck over a hatch, plug it in and run it. I might use it once or twice a year, if that - much less a pain in the butt.

I had a sport cruiser with A/C. It would drain two 4d batteries via inverter in about 45 minutes. I want to say it was about 12,000 btu's, but don't actually remember.

FYI!

Steve

What make, model and size boat do you want the a/c in?

I just installed a 12,000 BTU system for a client.

We used 3- 12v 280AH Lipo batteries in parallel, with a 2000-watt inverter/charger to charge from shore power, DC/DC charger to isolate lead house batts from LiPO and charge off alternators.

It was in a small pilothouse type boat, in the end with all the components it took up a lot of space and was heavier than you'd think.