Post Number: 1
|Posted on Monday, December 13, 2010 - 07:51 pm: ||
I would like to make some type of keel cooler for a 5hp Du Brie.
The ports on the engine and water pump are 3/8 pipe, the water tank has 3/8 ports and holds about 2 1/2 gals. I would like to hear of some experiences from anyone out there.
The ocean around here seldom gets below 70.
Thanks in advance,
Lou FL. Keys
Post Number: 536
|Posted on Wednesday, December 15, 2010 - 09:55 am: ||
You can go the technical roue and do some estimates using reasonable assumptions.
Here's a link to a heat exchange calculation guide.
Or you can use the experimental approach.
Your 5 HP DuBrie will probably generate 2 to 3 kW of heat that need to be removed. You can think of an air equivalent - roughly 2 electric baseboard heaters.
My estimate would be something like 2 or 3 runs of 1/2 nominal copper piping about 10-12 ft long, with a 2 or 3 gal tank inside the boat.
I recall that one of the guys in LA had a dory with a 2 cylinder (Kermath?) engine in which he used a keel cooler. I don't know what he had in terms of the piping for the cooler, though.
There might be more info from salt water sailors for their auxiliary power units. I haven't done a search on that.
Post Number: 925
|Posted on Wednesday, December 15, 2010 - 12:56 pm: ||
Seems to me I put a note on here some time back describing the keel coolers the working watermen used and they were practical simple approaches.
Remember the cooling surface for air cooling requires a much higher surface area than water for adequate heat transfer. For a typical planked hull say 18 feet over all they would run a single 3/4"copper pipe each side of the keel rubbing strip. Near the bow they would make a return bend using copper pipe fittings obtainable in almost any hardware store. Near the engine end of the boat they would bring the copper pipe up through the bottom each side of the rubbing strip. The typical expansion/supply water tank would simply be a 18" to 24" tall piece of copper pipe approximately 3" dia. The bottom cover would be a copper pipe cap brazed to the vertical pipe the top cap would be another copper pipe cap with an approximately 1/8" breather hole. Just lift the cap off to fill the system with fresh water. Add anti freeze if in a cold climate and you can avoid draining the keel cooling part of the system system in cold weather. The required circulating pump for the keel cooling rsystem can be driven off a V belt pulley mounted on a flywheel hub extension. Don't put the engine cooling circulating pump in the keel return line. Use it to inject sea water into exhaust piping cooling from original through hull intake. Pump output to be directly to exhaust piping just aft of exhaust manifold. Engine jacket/exhaust manifold cooling water outlet route near the top of the expansion tank. This allows one to lift the cap and insure cooling water is flowing. Use hose for connections to the engine to limit vibration transfer. Don't skimp and avoid putting sea cocks in the keel cooler inlet and outlet. The watermen simply painted anti fouling over the keel cooling pipes.
Hopes this give one approach you can try.
Post Number: 20
|Posted on Thursday, December 16, 2010 - 09:14 am: ||
8 HP,2 10 FT. RUNS 3\4 INCH COPPER, 3 GAL TANK.HAD TO INSTALL VALVE TO CONTROL FLOW TO BRING TEMP. UP.IF USING PISTON PUMP INSTALL ON SUCTION SIDE!
Post Number: 2
|Posted on Friday, December 17, 2010 - 03:53 pm: ||
This gave me some direction.