Keel Cooled Air Conditioning

[zboss]

Originally Posted by Dave22q

Water cooled less capital investment, at least equal efficiency and as I understand it, more reliable. Cleaning the coolant strainer every few weeks is not much of a burden. Also water temperature does not matter (in the Keys the ocean can go to the mid 80's.

In St. Augustine and in much of Florida, you need to clean them every few days. If you have a big boat, like many of our friends, you are cleaning 3 or 4 of them every three days during the summer.

[mako]

Originally Posted by zboss

In St. Augustine and in much of Florida, you need to clean them every few days. If you have a big boat, like many of our friends, you are cleaning 3 or 4 of them every three days during the summer.

Why? What is wrong with your friends' setups?

[DeborahLee]

Originally Posted by Yahoo

I tried this with disastrous results. I tried to use a Honda 2 kW portable generator to run a 6000 BTU window unit but the starting current required was too great and the Honda went into convulsions, finally vibrating itself overboard. Have you experienced any problems when first starting your window type air conditioner either with the invertor or portable generator?

How old was the unit? In the past couple years they have made great progress in lowering the amps. I use a 650 watt Honda on my 5000 btu with no trouble. You can usually get one and if it won't work return it. No cost trying just time.

[valhalla360]

Originally Posted by makobuilders

Why? What is wrong with your friends' setups?

If you are in an area with a lot of growth and floating debris, they can fill up in a few hours. We had that issue when anchoring near swampy areas and a lot of dead vegetation floating around. Might go a few days, might go a few hours. A real pain in the rear.

Nothing wrong with the setup, it's inherent to the design of raw water cooled air/con.

[zboss]

Originally Posted by makobuilders

Why? What is wrong with your friends' setups?

Nothing... the water in Florida is so full of nutrient runoff from the golf courses, farms, and pristinely curated lawns that the flora in the water is extremely prolific in summer. Lets not forget about the sewer overflows that happen in the rainy season or during high tides. There have been lots of algal blooms also.

You can't leave your A/C running even three days in July/August without the filters becoming completely clogged.

We have been using a window A/C unit the last few years. $100 from walmart and you can donate it at the end of the hot season and sail off.

[Just a Sailor]

Hi guys.
My background is as a Merchant Marine Engineer, so I can tell you, a lot of small ships use the keel coolant aproach, lots of tugboats, Supply ships, etc. and those systems are very very efficient, you avoid the need of pumps and a lot of cleaning of heat exchangers.
Even with the engines running iddle with the ship not moving, there is no overheat problem, water is always moving so there is the requested flow.
Also, there is no drag. The heat echangers are running on the inside side of the hull. Being it in steel, heat transfer is efficient.

So then why not in a Sailboat? there is no metal in the hull, only fiberglass so you would need a complete instalation out of the hull (costly), making it very exposed to any floting debris that may damage it, also having to deal with its regular cleaning, holes in the hull (the less, the better), large hoses to run the gas trough all the circuit (more conections, thus more chances of gas leakages), etc.

The more parts and complexity of any system, the more chance of a failure.

My aproach would be to make it the more simpliest way. The least moving parts, the least maintenance required, so then you will have the lesser costs and risks.
My two cents.

[sailorboy1]

Originally Posted by zboss

Is there a reason why keel cooled air conditioning systems are not more popular? I see boats constantly struggling with keeping their water cooled Air conditioners clean of debris.

I can clean the strainer for my seawater system and drop a disinfection tablet in it pretty easy. How hard it it to go down and clean a keel cooler heat exchanger?

[Outlaw7]

A keel cooler on a sailboat is impractical unless a pocket was fitted during hull layup way to much drag. Your next option is a heat exchanger, which will have a strainer and pump to deal with as well. However it limits the amount of water you are running through your boat, as all you have to deal with is just for the heat exchanger. With multiple self contained units you are running seawater hoses throughout the boat.
Sorry as Flagship Marine says, no free lunches in thermodynamics.

[Pauls]

Keel cooling on a fiberglass sailboat is practical if the boat has an exposed lead keel. The keel is cast with cooling pipes integral, meaning the pipes for the coolant are inserted into the mold before pouring and the lead is poured around them. Very low cost, zero drag, increased reliability, eliminates thru hulls, strainers, etc. But you have to plan for this during the build, something production boat builders do not do.

[zboss]

Originally Posted by sailorboy1

I can clean the strainer for my seawater system and drop a disinfection tablet in it pretty easy. How hard it it to go down and clean a keel cooler heat exchanger?

We get our frigoboat keel cooler cleaned every month when they clean the bottom of the boat.

FYI - a lot of boats have four seawater strainers for their A/C systems. The point of the keel cooler is to not have to worry about the water cooling.

[sailorboy1]

So it is a lot harder!

[zboss]

Originally Posted by sailorboy1

So it is a lot harder!

It is! I think that cleaning four strainers every week would be a real pain in the butt, hence the idea of a keel cooled system. We have to clean the bottom anyway, so why not?

However, I looks like it would take a very large sinter or like a previous poster mentioned, a cooling system built right into the keel itself.

[Cottontop]

Air cooled mini-splits?

[Outlaw7]

No, not mini-splits! They are horrible , freon lines running through the boat, shallow condensate pans, and the unit rust all over the deck!

[thinwater]

The disadvantage seems obvisous to me. You have two heat exchangers in series, which means the water to the AC unit will be warmer.

A normal system, 85F water circulates from the sea to the AC unit. With a keel cooler (or other split system), the 85F water is exchanged against a closed loop in the boat. Depending on HE efficiency, the closed loop may now be 90-95F after cooling. This 5-10 F bump won't matter for an engine if designed correctly, but it may be big trouble for an AC unit, particularly one that has a high cooling water cut off switch. It may not matter in cooler climates. AC cooling and engine cooling are different fish.

Just sayin', there is now some additional engineering required.