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Old dream 07-22-2013 08:37 PM

Keel cooling
 
Is their any reason I shouldn't use keel cooling with my yanmar sb12 on my 29 ft boat. How much drag can I expect to have . No interest in racing just want trouble free cooling. I have set it up on power boats with car engines that we modified but drag was not a issue for just cruising in the local bays and inlets.

rugosa 07-22-2013 09:38 PM

Re: Keel cooling
 
We used Walter Keel Coolers on a series of 34' hydrographic survey launches for Canadian Fisheries and Oceans in the 90's. Since we were laying up hulls on site we built foam blocks as hull recessess so coolers would be flush, reducing drag. Worked great, but drag could be a serious issue for you at sailing speeds. Best to get some serious designer input here.

Bilgewater 07-23-2013 12:13 AM

Re: Keel cooling
 
I've thought of that on occasion. Many of the boats and in particularly fish boats up here use keel coolers. They seem to work very well. This is just a guess but I think you would definitely need one on each side and you would loose half the cooling effect when your heeled over. Even if it's recessed you would get lots of drag.

SlowButSteady 07-23-2013 12:58 AM

Re: Keel cooling
 
Wouldn't using a keel cooler mean that the engine would have a dry exhaust? Not a problem on a larger motorboat, but I would think a dry (and very hot) exhaust on a sailboat could be problematic.

chuck53 07-23-2013 06:46 AM

Re: Keel cooling
 
Quote:

Originally Posted by SlowButSteady (Post 1063282)
Wouldn't using a keel cooler mean that the engine would have a dry exhaust? Not a problem on a larger motorboat, but I would think a dry (and very hot) exhaust on a sailboat could be problematic.

That was my initial thought when I started reading this thread. Thinking about my boat, I don't see anyway to make dry exhaust work.

smurphny 07-23-2013 07:00 AM

Re: Keel cooling
 
I've had keel coolers on workboats but they had exhausts that went up vertically through the deck. A small keel cooler would create very little drag but you'd still need to keep a wet exhaust unless you could devise some sort of exhaust exit that wouldn't melt lines or sails. Fumes might also be a problem. On workboats you're usually in the cabin when motoring and the exhaust pipe is pretty high.

Roger Long 07-23-2013 07:05 AM

Re: Keel cooling
 
Keel cooling is on the list of things I would like to do with my boat since I have a RW cooled engine. It's the least troublesome form of FW cooling there is.

For a sailboat, you would want to use a "Package Cooler" from Fernstrum or Walters instead of a bunch of pipe looped back and forth. You will be surprised how small it is for 20-30 hp. The boundary layer gets so thick towards the back of a boat that the drag won't be significant with a wedge in front of and behind the cooler.

Dry exhaust isn't practical. You will need to install a second water pump belted off the engine to provide exhaust water. You will also need a small header tank.

Raw water cooled engines like mine have a thermostat set to a temperature that is too low for optimum operation. This is necessary to keep salt deposits from quickly building up. One of the main reasons I would like to convert to keel cooling is to get the engine running hotter as well as being able to make domestic hot water.

Yanmar does not sell a thermostat with a higher setting which will fit my engine so I would need to remove the thermostat and replace it with an external one that would keep all the water in the keel cooler loop at the right temperature. As you can see, there are some design and engine specific issue so a keel cooler conversion should be done with some informed professional help.

Old dream 07-23-2013 07:58 AM

Re: Keel cooling
 
I will look into package coolers. I have only used cooling pipes on my power boats. Sailing is new to me takes a different mind set for sure. Still haven't found a good option for the exhaust. Don't like running a extra pump if I can help it back to the same problem I have now. Kelp,sea grass,plastic,jelly fish, all that good stuff plugging the intake. But at least I could throw a bucket of water on the pipe till I was out from the beach. I just love poking about in the little bays and estuaries ware most people don't go.


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