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Thread: Skookum Maru

  1. #421
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    Sep 2007
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    Default Re: Skookum Maru

    It pumps the expansion tank dry first. Some fluid would by pass the hole, but no water would get sucked in until the pressure dropped below the suction side pressure level.

  2. #422
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    Nov 2014
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    Default Re: Skookum Maru

    Good question. Ok, I haven't really been thinking about this but what I expect to happen is that since the system is under pressure if the cooler is breached underwater it will expel a certain amount of coolant until the system reaches pressure equilibrium with the surrounding water. At that point the pump should continue to circulate raw water unless it loses prime. As Ron notes, I don't think it can actually lose all of the coolant unless there is an opening to let air in. Which can't happen in a sealed system (e.g. one with a pressure cap on the header tank). But this is just coming from my shade tree mechanic experience so I could be entirely wrong.
    Last edited by cstevens; 09-22-2019 at 08:53 PM.
    - Chris

    Life is short. Go boating now!

  3. #423
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    Default Re: Skookum Maru

    Quote Originally Posted by navydog View Post
    It pumps the expansion tank dry first. Some fluid would by pass the hole, but no water would get sucked in until the pressure dropped below the suction side pressure level.
    Ok but how does it pump the tank dry if there is no way for air to get into the tank? At least on Petrel there is a pressure cap on the tank so it is not open to the atmosphere. I think we are saying pretty much the same thing regarding the expulsion of fluid under pressure, I just don't see how it can lose *all* the fluid.
    - Chris

    Life is short. Go boating now!

  4. #424
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    Dec 2009
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    Vancouver Island
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    Default Re: Skookum Maru

    I'm pretty sure the fix would be to repair the broken pipe and flush the system. Should continue to work after rupture until the unfiltered circuit plugs up with debris, perhaps not that long around here, judging from my raw water strainer. / Jim

  5. #425
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    Sep 2007
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    Default Re: Skookum Maru

    Quote Originally Posted by cstevens View Post
    Ok but how does it pump the tank dry if there is no way for air to get into the tank? At least on Petrel there is a pressure cap on the tank so it is not open to the atmosphere. I think we are saying pretty much the same thing regarding the expulsion of fluid under pressure, I just don't see how it can lose *all* the fluid.
    The expansion tank is under pressure from heated air. The low pressure from a hole will let the hot air push the fluid out. Eventually it would pull raw water in, but the system would be pulsating and not very efficient.

  6. #426
    Join Date
    Oct 2014
    Location
    SW Washington/ At Sea
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    286

    Default Re: Skookum Maru

    If the suction side is coming from the keel cooler the head pressure from the water will prime the pump...agreed it isn't an optimum setup but it won't go completely dry. I don't think it's really an issue though...the location of the cooler protects it as mentioned before.

  7. #427
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    Default Re: Skookum Maru

    Well, I think we are generally in agreement that it might continue to cool the engine or it might not depending, but in any event it’s not the most likely way you could ruin your day on the water. Seems like it will just have to remain a thought experiment unless anyone wants to cut a hole in their keel cooler in the spirit of science. No? Thought not. Ok then.
    - Chris

    Life is short. Go boating now!

  8. #428
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    Apr 2010
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    South Australia and Tasmania
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    19,438

    Default

    Guys it will just run like a raw water cooled system. Not rocket surgery.

    Sent from my CPH1851 using Tapatalk

  9. #429
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    Sep 2007
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    Default Re: Skookum Maru

    There is no raw water intake so it will not run the same.

  10. #430
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    Oct 2018
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    lagunitas, ca, usa
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    676

    Default Re: Skookum Maru

    The part that decided me was that, if anything happens to a keel cooler you have to haul the boat to fix it. With the inboard heat exchanger method, just close the seacock and get out the wrenches.

    I think the principle of a keel cooler is better. But in practice, it's real nice to be able to fix stuff anywhere, anytime.

    That's assuming that the seacock doesn't let go, which is something we just have to live with.

  11. #431
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    Jan 2008
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    Lynden, Wa
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    3,586

    Default Re: Skookum Maru

    Quote Originally Posted by cstevens View Post
    Fall has descended in earnest here in the Pacific Northwest. But we had family in town recently for a visit which coincided with a brief break in the weather so we took everyone for a tour around the lake in between rainy days.



    And now that we have Skookum Maru down here in Seattle we are looking forward to fall and winter cruising in Puget Sound. Poulsbo, Gig Harbor, Brownsville and other local destinations are only a couple of hours away. Time to fire up the diesel stove, make up a pot of hot chocolate, and break out the books and board games to while away the hours as the rain patters on the deck.


    That sounds amazing. What a lovely way to spend some time.
    There's the plan, then there's what actually happens.

    Ben Sebens, RN

    15' Welsford Navigator Inconceivable
    16' W. Simmons Mattinicus double ender ​Matty

  12. #432
    Join Date
    Apr 2012
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    San Diego and Gabriola
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    192

    Default Re: Skookum Maru

    Quote Originally Posted by BBSebens View Post
    That sounds amazing. What a lovely way to spend some time.
    Yes! Chris certainly has put together a good winter set up there.

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