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Sea Sprite 23 #110 (20)
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While my current boat does not have an inboard, I am looking at several larger boats to move up to. One of the ones I saw for sale had a keel cooler. I know how they work, it's pretty easy and I can see why it would be easier on the entire cooling system as it keeps salt water out of the boat and intercooler..

My question is thus.. I live in an area with a lot of "growth" on the bottoms of boats.. how do keel coolers cope when covered in a layer of green or a barnacle or two?
 

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One of None
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They need to somewhat clean. the water contact does still absorb most of the heat via transfer. It would take allot of crud to really insulate it from working...But the boat would need bottom cleaning anyway.
 

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For a sail boat a lot of drag ,clean or not. Requires a dry exhaust or a separate raw water pump. Unless the cooling water can be pumped down at idle (depends on pump) idle long time not so good. Well made and properly zinced work well.
 

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Over Hill Sailing Club
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Have had a couple of work boats with keel coolers. They work well and are simple and dependable but those boats, as mentioned, had dry stack exhausts. Unless you're racing, the drag is not all that much if the front casting of the cooler has a good hydrodynamic shape as most do. The drag is not much more really than a depth finder thru-hull unit. As long as the unit is deep enough to stay in the water when heeled over, I don't see any real downside. I can't ever remember a fouling/overheating issue.
 
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Corsair 24
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on a sailboat murphy or on a powerboat, fishing boat etc? dry stacks and keel coolers are really popular in colder waters and certain fishing areas around the world

I briefly had the thought about converting an air cooled diesel down here and dry stack it with some sort of keel cooler system on my boat...but still came out expensive...

not really worth it
 

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Over Hill Sailing Club
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on a sailboat murphy or on a powerboat, fishing boat etc? dry stacks and keel coolers are really popular in colder waters and certain fishing areas around the world

I briefly had the thought about converting an air cooled diesel down here and dry stack it with some sort of keel cooler system on my boat...but still came out expensive...

not really worth it
I had dry exhausts on a fish trapping boat and a clamboat. They work well but you have to deal with surrounding the stack so as to not burn stuff. They are also very noisy if unmuffled. One of my boats had a 440 Chrysler in it...up through a small muffler but it was noisy as all get out. Quite a few lobster boats have dry stacks too. In cold weather it eliminates water freezing solid overnight in an exhaust system. The only engine fluid is anti-freeze, unlike a typical heat exchanger which has salt water sitting in it as well as in the exhaust system parts.
 
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trying to find one(installation) on a sailboat....thanks
 

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We had a dry stack on the boat below. Heap big heat in the engine room. Most of the other commercial boats had keel coolers. Ours didn't & I had to dive, with no wet suit, in low 50 degree water, to pull a big gob of kelp off of the inlet strainer. IIRC, our exhaust manifold was salt water cooled from the downstream side of the heat exchanger. Even with that, the exhaust system radiated a lot of heat. If I was to buy another commercial boat it would have a keel cooler.

However, in the small confines of a sailboat, I think a dry exhaust pipe system, which gets very hot, close to combustible materials, might not be so good? Maybe one of the boat designers/builders could jump in & share their expertise?

Paul T
 

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Master Mariner
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If you have any designs on sailing tropical waters, I wouldn't consider a keel cooled boat. The only place I used them was off the left coast mostly from Frisco to Alaska and the water there rarely get above 60 degrees.
For cruising, as mentioned, they do cause significant drag and you now have added dis-similar metals below the waterline that require paint and maintenance.
 
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Wingnut
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Personally, I don't want any other system.

My boat will be keel cooled, Without any uneccesary drag do to using the hollow skeg as the radiator. It is streamlined, has the prop shaft shoved through it already, and Is also used to hang the rudder. (outboard, of course)

This eleminates the need for an addtional impeller pump, It also Completley eleminates the chance of clogging the water intake, because there isnt one.

It is also just nice thinking that there is no heat exchanger, and no salt water whatsoever anywhere in the engine.

As far as exhaust goes, I choose dry, because its simple. Yes, it gets hot, and you have to wrap it. No big deal tho.
And as far as noise goes, just dump it into the water after exiting the transom. Voila. no noise.
 

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you have a steel boat right? its pretty damn easy to rig on a steel boat, especially of you are in colder waters...

I like the idea if using the hollow skeg as the cooler too

pics?
 

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Wingnut
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I almost have a steel boat.
Still sitting inn the yard.
So, yeah it is easy to do with steel, and evenn easier to do if you are building it yourself from scratch.
Maybe i will upload a bunch of pictures one day, but for now, I dont have time.
 

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Our Isotherm in-water heat exchanger is a coil inside the bronze thru-hull fitting for our galley sink drain. The coil is completely within the hull fitting. The fitting itself looks much like a conventional fitting, but a little wider and notable for the ring of 1/4" perforations, and protrudes perhaps 3/16" so as to produce little disruption in flow over the hull. The first year we used a special zinc, but it proved unnecessary and we haven't used it since (at least 10 years).

We see absolutely no fouling inside the hull fitting and the coil is perfectly clean. My understanding is that the darkness inside the fitting and the heat associated with its function are more than sufficient to eliminate growth.
 

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Here's a picture of the isotherm thru hull. The center is carries the drain from the galley sink. The perforations allow water flow into the cooling coil area. Two of the perforations are threaded to accommodate a special zinc--if you need to use one. The marelon thru hull to the left accommodates a 5/8" raw water intake hose (for scale).

The photo was taken after installing the thru hull 11 years ago. The coil was virtually just as clean prior to launch this year and I have never had to touch it. It just wasn't as shiny as new.

 

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Sea Sprite 23 #110 (20)
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Discussion Starter #15
that is pretty cool (sorry about the pun!) looking
 

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My yacht has keel cooling no external pipes just a tank in the keel it works really well have had no issues.Never gotten hot when the boat has a furry bum.A lot less hassle than a heat exchanger
 

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Over Hill Sailing Club
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Here's a picture of the isotherm thru hull. The center is carries the drain from the galley sink. The perforations allow water flow into the cooling coil area. Two of the perforations are threaded to accommodate a special zinc--if you need to use one. The marelon thru hull to the left accommodates a 5/8" raw water intake hose (for scale).

The photo was taken after installing the thru hull 11 years ago. The coil was virtually just as clean prior to launch this year and I have never had to touch it. It just wasn't as shiny as new.

Ditto here. I have the same thru-hull and spent last winter in very warm, growth-prone water. The inside of the device remained clean.
 

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1974 Cal 29
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In debating my diesel re-power, I've considered some air-cooled diesels. My plan was to cool the oil for the engine. I would use the existing through-hull to let sea-water into a tube, inside which a coil of copper tubing is wound for the oil to run through. A diaphragm pump would pull water out of the other end of the tube and pump it into the exhaust pipe. The only concern is that a broken oil cooler line would lead to seawater in the wrong part of the engine!
 

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Most transmissions are water cooled so there's no problem in cooling engine oil same way but why a 'diaphragm ' pump? go to all the trouble of bringing salt water in and cooling the exhaust and still have to deal with lots of hot air and noise. As for keel cooling, big difference between the needs of a little fridge and a 671 Jimmy.
 

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1974 Cal 29
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It's a small electric 300GPH diaphragm pump. I already have it, and figured it would be the easiest way to rig a pump, as it's just a few hose-clamps to hook up to the heat exchanger.

I'm not really sure of any electric water pump that is rated to run for days at a time....
 
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