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Old 13-03-2019, 12:50   #31

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Re: How to run an 18000BTU A/C at Anchor

The "EasyStart" is not just a traditional "soft starter", but it apparently is very effective. There are some YT posts on it, the Wynns used one to make their RV (now boat) AC work.

Ed, you may find the only reasonable (which also means expensive) solution is a massive lithium battery bank with all new matching charging system and gobs of solar or wind power to keep it fed. And if there's enough wind for a wind charger to help...there's probably enough breeze to be of some help too. Which brings you back to needing more solar watts than your AC consumes. If you figure, you may want two or three days of power to get through cloudy humid days...

This is the good lord's way of telling folks that Florida was not and will never be the Garden of Eden.

Although from a Yankee point of view, there's nothing wrong with Florida that a six inch layer of concrete, some good sewers, and a big glass bubble couldn't fix.

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Old 13-03-2019, 13:53   #32
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Re: How to run an 18000BTU A/C at Anchor

The previous owner obviously only used the A/C with dock power. 18,000BTU seems a little much for a 38' (I assume a monohull). My 47 Cat (with two hulls, five cabins and a big solon) has 54,000 and a 9.5kw gen to run them.

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Old 13-03-2019, 14:16   #33
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Re: How to run an 18000BTU A/C at Anchor

Hi Jim yes it is a monohull. Most likely they did use it on shore power. I would like to use it while anchored somewhere on a trip. Thks for the input.
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Old 13-03-2019, 14:19   #34
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Re: How to run an 18000BTU A/C at Anchor

Just because you dont want to pay for a next gen does not mean you will not want one !
In the lazerette or sail locker !
The generator will set you free. Or get a slip and have 110V power !
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Old 13-03-2019, 14:28   #35
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Re: How to run an 18000BTU A/C at Anchor

The reality of the matter is that everything has been taken up by extra water tanks for the water maker and batteries. The cost of a Genset installed is about 20% of the price that I paid for the boat. That doesn't make too much sense. I will not be living on the boat. It is basically for the weekend trips 4 to 6 times a year.
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Old 13-03-2019, 14:33   #36
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How to run an 18000BTU A/C at Anchor

When I installed my AC’s I did so with the idea of being able to sleep with AC on if I wanted to.
I have a 16K in our Salon and a 6K in the Fwd Salon. A Honda will run the 6 k in eco mode, but won’t start this particular 16k, some it will, a Webasto it won’t.
So I can charge batteries and run our bedroom AC and be cool to sleep off one Honda.

Originally my plan was two Honda’s run in parallel as they can provide 26 amps rated, and actually more. Two Honda’s will run a complete 30 amp Boat just like it was on shore power.
What worked best was both Honda’s in the dinghy and connected to the dinghy fuel tank to give them extended run capability, but two Honda’s in the dinghy is a PIA.
I ended up with a 3.5 KW Nexgen, which will make about 27 amps continuously and will run the whole boat.
It burns on average about a quart an hour.
I figure on replacement cost alone, no fuel and no maintenance, it costs $1 an hour to run, double that with fuel and maintenance, repairs, parts etc.
$50 a full day, every day. $1500 a month, and an oil change every four days. The 3.5 Nexgen recommended oil change interval is every 100 hours.
You can see how a slip gets less expensive pretty quick, and a whole lot less aggravation.
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Old 13-03-2019, 14:50   #37
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Re: How to run an 18000BTU A/C at Anchor

I understand about the slip. In S. Florida there is a waitlist of 4 years for a slip where I am. I would also like to use it while I am at anchor somewhere.
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Old 13-03-2019, 15:23   #38
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Re: How to run an 18000BTU A/C at Anchor

We have a similar climate to Florida and so I can understand the temptation for AC. Just remember there is nothing more infuriating than being anchored in a beautiful location on a nice balmy night, hatches open to catch the gentle breeze..... And some Wayne Kerr anchors upwind, cranks up the noisy, smelly generator and then closes all his hatches to keep the cool in and the noise and pollution out.... Instant arsehole! And of course what is the point in being out on the water if you just lock yourself away down in the cabin? Might as well stay at home!
The real problem is that so many boats are designed with insufficient ventilation for a tropical or subtropical climate. Especially European boats. Perhaps understandable when you realise the French Riviera is a similar latitude to New York or Hobart. There are ways to improve ventilation on a boat that are much cheaper, easier and neighbouring-boat-friendly than AC.
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Old 13-03-2019, 16:29   #39
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Re: How to run an 18000BTU A/C at Anchor

Forget batteries completely wrt the aircon.

Size & run the genny to power the aircon.

Charge the bank separately, solar may be enough.
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Old 13-03-2019, 16:54   #40
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Re: How to run an 18000BTU A/C at Anchor

In South Florida in the summer for most sailors the AC is the most important equipment on the vessel, next to the bilge pump. I would add a commercial diesel generator, fuel tank and AC with the capacity to cool the living spaces.
I spent a week in port in Bandar Abbas Iran once in their summer if I remember correctly the sea water was at 90F and the AC could not work correctly. Hopefully it is not that way in South Florida.
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Old 13-03-2019, 18:02   #41
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Re: How to run an 18000BTU A/C at Anchor

We have a Dometic/Cruisair 12,000 BTU system with soft start running off a Xantex PROsine 1800W inverter fed from 3 x Lifeline AGM125AHr batteries when we are at anchor HOWEVER we do not run it for more than 10min intervals unless we start the 12V diesel genset. What we do if we're rafted up and do not wish to disturb our neighbours is turn it on in the evening just before we shower and get ready for bed, we run it for about 10mins, stop it turn it on for 10mins after a 10min break and then same again. With the boat (42ft yacht) closed up we can bring the internal temp down by about 5C to 7C doing this without running the gen set, which makes a difference when you're sweltering! This draws about 55A from the inverter (as 12V) but only for a short time. The trick is not to ramp it up full and make the air con go hard. If you don't ask it to perform miracles it will provide cooling using only about 15A (at 12V). If you run it a bit harder then up to 50A and on full power puts about 75A load @ 12V on the inverter when cooling.
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Old 13-03-2019, 18:59   #42
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Re: How to run an 18000BTU A/C at Anchor

Buy fans. If you cannot live without AC sell the boat.

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Old 14-03-2019, 06:03   #43
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Re: How to run an 18000BTU A/C at Anchor

Instead of AC, consider powerful fans.
I've been very pleased with an option from RYOBI power tools...18V ONE+ Hybrid Fan. Runs for several hours on the 18V battery, or remove the battery and run on 120V extension cord. I use one below, another installed directly over the hatch to push in cooler evening air. About 10x the air circulation of marine 12V fans.
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Old 14-03-2019, 06:50   #44
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Re: How to run an 18000BTU A/C at Anchor

Never had a/c in nearly 40 yrs, on any boat that we have sailed world wide including the caribbean.

Also do not have trash compactors, or generators, etc., and on land we lived in southern calif and kauai island. No a/c in socal at our residences .

1. In the caribbean, on board we open up the hatches, and used wind scoops, and small fans, and the same for coastal sailing and catalina island in socal.

2. As to generators, at night they make one heck of a lot of noise transmitted thru the water from the boats using the generators and the regs are that generators are shut down at 10 pm. The rest of us in the mooring field would like to sleep at night.

3. On kauai Island, it would get pretty hot. We had those near worthless window air conditioners. and the cost of electricity was horrendous. Not to mention the bloody
thing sounded like an overloaded slick departing a hot L.Z.

We would run the window A/c before we went to bed, and took cool showers before hitting the rack. Also , we do not wear any mickey mouse pajamas, at anytime, anywhere. The comfort level lasted long enough for us to get to sleep.

Also, when we got ready to go to sleep we would turn off the window a/c, plus we did have ceiling fans, and that helped .a lot. We also opened the sliders and jaolused windows to let the trades cool us, if they were blowing. That would help to cool us down as best as nature could.

We also use one top sheet, or no top sheet. No blankets or covers. If the trades stopped and the breezed quit, we had the ceiling fan, and open windows and no top sheet or covers .

After 10 yrs on kauai, we have moved back to the southern calif, beach area, dana point, and do not have any A/C ... zero. And no ceiling fans. We now rely on
the prevailing westerlies, but most times the land temps and the ocean temps
equalize in the evening , and the wind stops and we just have to live with the heat.

We love where we live, and chose to live and do our best with what mother nature gives us.

Positive side . For land, You can buy have a portable air conditioning unit that some of the neighbors use in their bedrooms only. Actually, it takes up a bit of room, not sure it would be compatible on boats. That beast works pretty darned well.
Not sure if it would fit on board at a slip.

If it were us, and A/c was imperative, on an anchored boat, we might abandon the hook and would probably find a reasonable slip that had electric shore power, with enough juice to run the a.c.

Yep, to keep life simple and easy, and to our comfort level. At anchor, there seems to be too many watts, volts, solar, batteries, inverters, generators, compressors, open wires, nuclear energy problems etc., and a huge general PIA factor .

Without A/C, We would use the open hatches, sleep in the buff, windscoops, fans, or better yet, that idea of a slip with shore power at a nice friendly marina , with an air conditioned bar and a bevy of beach bunnies a few steps away for the fun factor. might
be a good plan.

Cannot tell the OP what to do, just how we would handle it were it us.

Hope, he can find a solution for r his personal comfort zone, and enjoy manageable living conditions on board.

Moving to Maine, or any cold, ice, snow and blizzards is not in our great plan.
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Old 14-03-2019, 19:33   #45
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Re: How to run an 18000BTU A/C at Anchor

Originally Posted by stormalong View Post
Open the hatches, add a windscoop or two and enjoy the silence.
The windscoops really do make a huge difference.

I had a Hunter Legend 35.5 with 16000BTU A/C. At the dock it was wonderful (plugged into shorepower). At anchor, I never once felt like I needed it. At anchor its usually quite a bit cooler than ashore. I remember often coming into the marina and just feeling the heat increase as we approached.

12 volt fans help too.

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