Solar-Powered Air Conditioning ?

[rtbates]

It's not the temperture that's the biggest problem, it's the humidity...

You either learn to at least tolerate it, if not love it, or pick a different life style.

[SeaBungalow]

I agree with the others on this thread about the fans and air-conditioning not a reality while anchored. We are currently cruising in Florida and were anchored out in 90 degree heat with no real uncomfortableness at night when it gets down to maybe 80. If you have enough hatches and ports open you get a good breeze, even better with the wind scoops, and we do use them.

We used to have a problem with the sweaty sheets but we found a solution after trying many different kinds of fabrics on the bed. Fleece. It may sound counter-productive to staying cool but it really works. We have a thick fleece blanket as the bottom sheet and a thinner one for the top sheet. They never feel damp or sticky and enough air flows through them to keep you cool. Much better than high count cotton sheets!

[SaucySailoress]

I gotta say - Skip actually managed to set up a system whereby the solar panels power the the refrigerator - with some power left over - but even with the mega sunn in Kuwait, it's not possible to run A/C off solar, unless we cover entire boat in solar panels!!!

So, with temperatures hitting over 50C during the day now (that's 122F in American speak), we have it run off shore power on a timer, and it's much appreciated when we arrive on the boat!!!

That said - even in the heat of summer, in the depths of the desert, we have not ONCE found a need to run the A/C whilst at sea!!! On our old boat we used to sometimes switch on the fans, but don't have them on this one (sore point), and a combination of shade, wind scoops and swimming works to keep us cool at sea.

[DannySt]

I would add to the wind scoop a boat tent (I would guess any fabric will do) to go over the boom, preferably all the way to the forestay, worked wonders for cruising the med in July/ August. combine that with a wind scoop over the hatch and you have a winning formula.
Plus - it add to the privacy of the cockpit. Minus - you need to be fast on your feet if you need to get out of an anchorage asap.

[clockwork orange]

Anyone tried using the full bow to stern shade covers combined with a small pump pumping seawater to a soak hose at the ridge to try to create evaporative cooling ? i dont know if it would work but it sure worked to provide icy cold water in canvas water bags when i lived in Australia years ago.
Steve.

[yttrill]

I think it would be hard to run AC on solar "all the time", but it is probably possible to take the edge off the mid-day heat. I have 10x80W panels which generates over 50 amps at noon in summer, most of this power is wasted. With 1800Ah batteries I can easily afford 180Ah or 10% of my capacity and still recharge. Still, washing down the steel deck is probably more effective at absorbing excess heat both by transporting away warmed up water and by evaporation. I don't have an aircon though, and don't plan on getting one.. rather use up that energy nuking coffee

[SaucySailoress]

Originally Posted by DannySt

I would add to the wind scoop a boat tent (I would guess any fabric will do) to go over the boom, preferably all the way to the forestay, worked wonders for cruising the med in July/ August. combine that with a wind scoop over the hatch and you have a winning formula.
Plus - it add to the privacy of the cockpit. Minus - you need to be fast on your feet if you need to get out of an anchorage asap.

We have a similar set up on our boat. From the bimini, we have two shades that fold out on stainless steel piping. One forwards and one backwards. We keep those open most of the year to keep the decking a little bit shaded from our 50 deg C summer sun (that's 120F+ for Americans).

THEN - to the opened up canopy, we attach TWO flat sun shades which run forward to the side stays. These clip together in the middle - and can also be clipped together under the loose footed mainsail, so we don't even have to take it down to raise the sails. The only probem - we can't see the wind indicator, but even that's not a problem if we remember to switch on the instruments!!

[wildshore]

I did see, a number of years ago, a livaboard who had rigged up a small solar pump to pump seawater through a disused set of condenser coils over his forward hatch. As long as the water was below ambient air temp (and it usually is) it managed to pump somewhat dryed, cooled air into the cabin.

Well, I thought it was clever, anyway

[Skipper Dan]

This is the approach I was thinking. Being in the water busines I know that you can send down a hose as far as you want without any strain on the pump, (It pumps from the level of the water) I would think that 20' down the water is rather cold. You do not even need a fan if the air is coming through the hatch. If you want to dehumidify it close the hatch and recurcualte the air using a fan collecting the condensation with a pan and hose to drain.
The rule of thumb is it is cheaper to transfer energy that to produce it. With a compressor you are producing it. With seawater you are exchanging it. To do it right duct the air from one side of the cabin with a 4" dryer hose blowing through the small heater core radiator.

Dan

[s/v Beth]

Does anyone use a heat pump for air conditioning? One that can be used as a heater during the winter- and probably keel pumbed.

[yttrill]

Skipper Dan said: "The rule of thumb is it is cheaper to transfer energy that to produce it. With a compressor you are producing it"

Of course tihis is not true; it's against the most basic law of physics called "Conservation of Energy" which says energy can neither be created nor destroyed.

Anyhow two more thoughts:

Don't forget colour. A blue canvas spray dodger on my yacht has been measured at over 50C in summer, it is easily cooled with water. Blue was a bad colour for summer shade cloth. My yacht is red which is good for cold climates but since I sail moderate and tropical waters I painted the deck white. [I can't give up the red because it is so easy to identify my boat by just saying "it's the red one" :]

I have a Peltier effect cooler on my yacht, this works using two metals such that passing a current through heats one side and cools the other. It's effective at knocking 5-10C off ambient in a small cool box and drawing about 1a at 12v, however it is only 10% efficient compared with over 60% for a compressor. However it is in theory solid state although my unit has a pair of fans which make more noise than my freezer.

Peltier effect works backwards too. Using a heat pipe and plates in the sun and in the water you can generate electricity silently whenever the external temperature is higher than water temperature. Although is isn't efficient the main cost is the weight and space of the equipment. A 1 amp Peltier generator is enough to run emergency lighting and your depth sounder. Especially useful on a steel boat where the hull is already a good conductor (which is makes steel boats a nightmare for liveable temperature maintenance).

[DotDun]

Originally Posted by s/v Beth

Does anyone use a heat pump for air conditioning? One that can be used as a heater during the winter- and probably keel pumbed.

I assume you mean reverse-cycle air conditioners? Yep, they heat in the winter.

Lots of models available. Mine use raw water, no keel cooling.

The updated version of mine are:
products - Dometic

[roberts]

Reading all the posts on A/C systems, I was looking to see if anyone ever installed the NITE system in the berth. This system puts out 7,500BTU/h 2.2kw and draws 25 to 65 amps at 12 volts, It uses 4 AGM batteries 6 or 12v. and runs for 8 to 10 hours advertised. I have found that they will run longer depending on how hard it is ran.
I have this system in a small feet of trucks for the last 4 years and have only replace the batteries in one truck due to an alternator charging failure charging at 16 volts and smoked the AGM batteries.
The batteries are dedicated to the A/C and heating system but share the same charging system. I maybe just lucky but I have never had a problem in the the 4 years with the A/C systems. The heating is done by an ESPAR so the annual maintenance kit and few fan failures.
The question I have before installing this in a berth would be the charging of the boats plus the NITE systems batteries. Wich could be used for other things if A/C is nt needed. From some of the numbers given above on solar panels it looks doable on the boat. Just curious if anyone else has thought about installing this system. NITE System - The World's Most Efficient No-Idle Thermal Environment

[denverd0n]

The NITE system doesn't appear to me to be anymore efficient than the typical systems usually put in boats. It is just a self-contained version of same.

And you're not going to run that thing exclusively off of solar anymore than you would any other air conditioner. It uses up a good couple of hundred amp/hours per night of running, so you'd need to have a MASSIVE solar panel installation to put all that back and still run all your other electrical needs.

[Sailmonkey]

I don't see replacing typically 650 amphours with a solar array on a boat, also the battery bank to maintain a lifespan would need to be around 1300 AH. On a truck that's going to stay DOT hours of service legal I can see how this would work, but not with solar, only through 14 hours of driving.