Keel Cooled Diesel

Discussion in 'Boat Design' started by Capt. Flint, Sep 24, 2018.

  1. Capt. Flint
    Joined: Apr 2018
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    Location: Alabama

    Capt. Flint Junior Member

    I have a 1946 wood downeaster style boat that I’ve bought. I’m currently repairing her, after everything is repaired I’ll be tearing the cabin down and rebuilding it from the ground up. Essentially, I’m building the bought that I want. She’s powered with a 3304 CAT Diesel engine and fitted with wet exhaust. My personal preference is dry exhaust with a dry stack and keel cooling. I have a two part question.
    1) I’ve read about people making their own keel cooler, but I have no idea where to start. Has anyone built their own? What all parts will I need?
    2) Since I’m converting from wet to dry exhaust w/ a stack, how do I need to go about doing this? What parts will I need?

    I’ve looked over forums and can’t find one about DIY keel coolers or wet to dry conversions for diesels. Any help will be GREATLY appreciated!!

    - Flint
     
  2. Capt. Flint
    Joined: Apr 2018
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    Location: Alabama

    Capt. Flint Junior Member

    She is making a 160hp, by the way. If anyone has pictures of their DIY keel coolers and dry exhaust/stack setup please post them!! Thanks in advance!!

    - Flint
     
  3. The Q
    Joined: Feb 2014
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    Location: Norfolk, UK

    The Q Senior Member

    my old engine was only 35 HP, but had a keel cooler. 1 inch-ish copper pipe through hull, Tee'd off into 3, 4 foot long pipes Tee'd back together and back through the hull. It worked very well, and if I could I would have done the same with the generator I now have. ( the genny has a built in wet exhaust I can't change without huge expence)
     
    Last edited: Sep 24, 2018
  4. bajansailor
    Joined: Oct 2007
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    Location: Barbados

    bajansailor Marine Surveyor

    Have a look at the Fernstrum site for some general reference info re keel coolers -
    GRIDCOOLER® Keel Cooler | Fernstrum https://www.fernstrum.com/products/gridcooler-keel-cooler/

    I think that the original 46' Nordhavn has keel cooling for her main propulsion engine (and all of the other long range Nordhavns do as well).
    Welcome to Nordhavn.com - Power Thats Oceans Apart http://www.nordhavn.com/resources/tech/exhaust.php

    A good article in Passagemaker
    https://www.passagemaker.com/technical/a-keel-cooler-retrofit

    Have a look also at post #9 by Angelique in this thread -
    Engine for Antarctica https://www.boatdesign.net/threads/engine-for-antarctica.61029/
     
    Last edited: Sep 24, 2018
  5. Tad
    Joined: Mar 2002
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    Location: Flattop Islands

    Tad Boat Designer

    The variables are heat rejection of the engine, the thermal conductivity of metals, water temperature, and speed. On the BC coast it used to be standard practice to run a long loop of 1" galvanized waterpipe along the keel, pretty much the full length of the boat, as a cooling circuit for a smallish gas engine. Big diesel tugs use multiple runs of steel channel welded to the hull bottom. They spend a lot of time moving at one knot or less. An old rule of thumb requires .333 sq ft per BHP for steel and .167 sq ft per BHP for aluminum. Copper would be lower yet. That may come from the Caterpillar installation guide.
     
  6. Capt. Flint
    Joined: Apr 2018
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    Location: Alabama

    Capt. Flint Junior Member

    I actually just got done reading a few posts of your’s on a similar subject from 2012. I found the math portion to figure out the length and what size to use. I’ll end up using 1-1/2" pipe with the inlet and outlet contained in one thru-hull fitting at one end of cooler 9-1/8" maximum width x 2" deep x 96" overall length. Although, I’m considering running it the length of the boat instead of bending it and keeping it in one area. Now I just need to figure out what other parts I need for the keel cooler, what parts I’ll need for the 3304 CAT engine in order to run keel cooling, how to hook up the keel cooler, & how to convert the exhaust from wet to dry w/ a dry stack. Any ideas?
     
  7. BlueBell
    Joined: May 2017
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    Location: Victoria BC Canada

    BlueBell Ahhhhh...

    Flex hose.

    I would think recessing the tubing in the hull would go a long way in extending it's life.
     
  8. Capt. Flint
    Joined: Apr 2018
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    Location: Alabama

    Capt. Flint Junior Member

    Do you mean recessing the keel cooler tubing into the hull? And what would the use of the flex hose be for? Sorry, I’ve got fifty-leven things on my mind right now :confused:
     
  9. BlueBell
    Joined: May 2017
    Posts: 427
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    Location: Victoria BC Canada

    BlueBell Ahhhhh...

    You asked, "Any ideas?"
    I responded: "Flex hose" referring to the joint between the diesel and through-hull to the tubing.

    Yes, not enclosing it but allowing anything hard like a rock, freighter, 90' deadhead to scrape by without touching the tubing.
    Recessing the tubing, depressing it, if you will, into the hull.
    Or even making the keel hollow and flow through while protecting the tube within.

    What kind of "Ideas" did you have in mind ( when you asked "Any ideas?"?
     
  10. Capt. Flint
    Joined: Apr 2018
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    Location: Alabama

    Capt. Flint Junior Member

    Ah, I see what you meant by flex hose now. I meant any ideas on how to convert the exhaust from wet to dry w/ a dry stack. Since the engine will be keel cooled, and the exhaust and water no longer going out the same pipe, the exhaust pipe should be free to run up through the deck correct?
     
  11. JSL
    Joined: Nov 2012
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    Location: Delta BC

    JSL Senior Member

    Try going to your CAT dealer and asking them. Even an installation book could be handy.
    Fernstrum is a good source for coolers. Making your own... be careful.
     
    Capt. Flint likes this.
  12. Tad
    Joined: Mar 2002
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    Location: Flattop Islands

    Tad Boat Designer

    A '46 downeaster is going to be a wooden boat and recessing anything in the hull is unworkable. The usual thing is to fit big wooden fairing blocks ahead and behind the external cooling pipes. The cooling system will need an expansion tank, the high point of the system. Cat made one that replaced the heat exchanger, you may be able to find one or trade your heat exchanger for one. Or you can just weld up a tank. The Cat installation book can help a bit with the circuit layout. Lobster boats usually built a jacketed exhaust elbow, which will replace the salt water injector elbow. It's just a flanged exhaust elbow welded into a big can that's part of the cooling water circuit. I have a drawing of one somewhere.
     
  13. Capt. Flint
    Joined: Apr 2018
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    Location: Alabama

    Capt. Flint Junior Member

    That’s what I was thinking, I wasn’t even going to try recessing the pipes into the hull. I am going to be using the fairing block method. Would you be so kind to look for that drawing, Tad? I’d appreciate it! No rush, I have plenty of time
     
  14. Capt. Flint
    Joined: Apr 2018
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    Location: Alabama

    Capt. Flint Junior Member

    I found both of these here. The one below is made for my engine.
    Cat 3304 Expansion Tank http://www.surplusman.com/Detail.php?itemid=6340

    I found this other one on eBay. They look to be the same
     

    Attached Files:


  15. Capt. Flint
    Joined: Apr 2018
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    Location: Alabama

    Capt. Flint Junior Member

    If I were to make a tank, what could I make one out of?
     
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