Keel cooling

Discussion in 'Diesel Engines' started by forkliftking, Jun 28, 2009.

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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    Thermostats don't work so fast it would cause such problems.

    Come to Florida , you can have a ride on our 6-71 powered 50 ft US Navy Utility , converted to a cruiser.

    The engine runs 180F (two new thermostats) and when the pair open the water drips to 160 , and in 4 or 5 min its back to 180.

    We are in Florida , the water temp is usually over 60F , the keel cooler is 2 lengths of 1 1/2 water pipe 21 ft long .

    Yes over cooling IS a problem. And a bypass thermostat is one solution.

  2. TeddyDiver
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    Location: Finland/Norway

    TeddyDiver Gollywobbler

    :D Maybe 20F lower temp for few minutes is problem for you but that's nothing.. Drill a bit bigger hole on the thermostate plates (hole that allows a bit circ to cooler when the thermostate is closed).. problem solved.
    BR Teddy
  3. Submarine Tom

    Submarine Tom Previous Member

    OR... tandem your thermostats for higher flow rate...

    You may want to try staggering the opening temps: one higher than the other, I don't know...

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    Location: S. California Junior Member

    No formulas, just past experience on a typical 15 K's boat with a 300 HP diesel-- 40 ft of 2" galvanized pipe has no issues keeping the engine right at the 180 F thermostat level in 60F water under varied operating conditions.... Never used the vessel as a tug or push boat (WOT with zero head way), but that's a different set set of calcs.. Maybe 50-100% more pipe??


  5. singleprop
    Joined: Mar 2008
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    Location: Hong Kong

    singleprop Junior Member

    I used John Deere Document AG-24 to calculate the length. I think it is quite conservative (no extra padding needed) and I came up with a total of 150 feet of 3.5" half pipes divided into 3 pipes of 25 feet on each side of the keel..for a 160 HP engine!

    It seem a lot but if JD are using these numbers then I can too......

    The document is quite specific with input data such as pump flow, heat rejection numbers (BTU/MIN), number of half pipes, boat speed, pipe size.

    If anyone has the document can they help me confirm that my calculations are correct, based on a 160 HP engine, 5100 BTU/min, 6 kts and 3 parallel paths???

    I think that I will arrange each run with a manual shut-off valve so that I can finetune the flow to keep the keel cooler return temperature around 20 degree lower.
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