The perfect Passagemaker III, propulsion

Discussion in 'Boat Design' started by apex1, Aug 26, 2010.

?

Please pick your poison

  1. Trawler: single Mitsubishi

    14 vote(s)
    35.0%
  2. Trawler: twin Luggers

    11 vote(s)
    27.5%
  3. Yacht: single Grenaa Diesel

    13 vote(s)
    32.5%
  4. Yacht: twin Mitsubishi´s

    2 vote(s)
    5.0%
  5. Yacht: twin Luggers

    4 vote(s)
    10.0%
  6. I am fine with less accommodation in favour of a large engine room.

    26 vote(s)
    65.0%
  7. I prefer large accommodation, the engine room is second.

    2 vote(s)
    5.0%
Multiple votes are allowed.
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  1. wardd
    Joined: Apr 2009
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    wardd Senior Member

    would all the fuel in all tanks go bad all at once?

    if it was all bad how would you get out to the middle of the ocean?

    maybe boat fuel system could borrow some ideas from aviation
     
  2. philSweet
    Joined: May 2008
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    Location: Beaufort, SC and H'ville, NC

    philSweet Senior Member

    With a CPP as given, I think that will skew the poll results compared to having left that an open question.
     
  3. apex1

    apex1 Guest

    Ja, that is the common understanding.
    Life is different.

    Apart from menmade issues*, fuel is the main problem with ships engines. Proper polishing solves that completely. A proper separator is between 5000 and 8000$, a low cost device, compared to the saved engine wear and trouble.

    A fouled prop is the second common problem.

    A single prop is much better protected than a twin, very much better! Keel and skeg act as deflectors.
    A twin prop catching a rope or net will in most cases invite his sibling to meet the fete.

    * the people (90% of the boaters) too lazy, stingy, or dumb to replace a impeller every year.
    The yard that installs sea cocks in a position only a octopus can ever access.
    Or the owners (again 90%) never closing a seacock. They have to be operated regularely!
    Pulley belts never checked, never replaced.
    Strainers clogged by hundred years old marine growth.
    Prop shafts and glands inaccessible and never serviced.
    Piping made of junk yard jewels, never pressure tested, never maintained.
    Fully electronically controlled and operated engines with a wiring to 1888 years standards.
    Engine boxes, the size of a rabbit hutch. Warm and cozy in winter, killing the engine in summer. Nothing in reach, nothing to service, nothing to even inspect.
    But a hughe owners stateroom where a football team could sit around a campfire without feeling cramped or bringing the curtains in danger.

    That list could be about 50 positions long! But I don´t want to bother the audience.

    Just one more point.
    Why has the engine to be started in the engine room?


    Right! If that is already a burden, you will NEVER do any service down there.
    So, force the people to survive their lazyness.

    Regards
    Richard
     
  4. apex1

    apex1 Guest

    There is no open question. I build such vessel with a CPP only! Anything else is mad, costly and senseless. Why would one vote for it?
    You did not follow the link provided? No...

    Probably they don´t go bad all at once.
    And you go some hundreds or thousands of miles before you recognize the fuel they sold you was the popular 50/50 mix.

    You would have a range issue than. But a separator tells you (by the water output) that someone sold you that nice stuff.

    It can take a few days before the fuel separates in the tanks, and big Diesels can bear a lot of **** before one does notice whats wrong.

    Regards
    Richard
     
  5. wardd
    Joined: Apr 2009
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    Location: usa

    wardd Senior Member

    aren't there sensors that could detect contaminants in fuel?
     
  6. apex1

    apex1 Guest

    They are not common.

    And one can make a vessel unuseable by installing every affordable gimmick.

    In fact 99% of the boats above some 70ft or 20meter on the market, at present have a severe overload of senseless ****. That makes them a reliable source of income in every marina.
    The average yacht above that line is a permanent construction site, not a boat.

    A sensor would help against the 50/50 mix but condensation (which is not to avoid) makes a separator much more useful.

    Richard
     
  7. dskira

    dskira Previous Member

    Wesphalia, Alfa-Laval

    Daniel
     
  8. RHP
    Joined: Nov 2005
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    Location: Singapore

    RHP Senior Member

    I know noithing on this subject so I would defer to the designer who, after all, has designed the boat to perform a function and should know the ideal power combination and size of engine room.
     
  9. apex1

    apex1 Guest

    He asks these questions.........;)


    Daniel,


    both are equal in all properties.
     
  10. apex1

    apex1 Guest

    Time for some negative feedback
     
  11. DennisRB
    Joined: Sep 2004
    Posts: 1,270
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    Location: Brisbane

    DennisRB Senior Member

    :p

    I voted for large engine room as I want to see what is going on in there and be able to do maintenance easily. Also the engine room would be my most favorite part of the ship. I would probably hang out there with my mates and drink beer and talk about all the awesome gizmo's and how much horsepower it has compared to their boat. :p I would want it to look the the Dashews engine bays bordering on art it is that well thought out. So yeah the engine bay would be very important to me.

    I didn't vote for single or twin as I don't have the knowledge to make a decent choice. But single seems the way to go for costs and space. I agree that if commercial shipping uses a single engine, yachtsmen should not be scared to do so.
     
  12. Pierre R
    Joined: May 2007
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    Location: ohio, USA

    Pierre R Senior Member

    I have but one question that has been bugging me. Since the options call for the possibility of two engines but only a CCP how do you sycronize two CCP's? I have a CCP in my present boat and cannot imagine getting the pitch and rpm the same on two.

    My thoughts are that the engine has to last as long as I figure I am going to use the boat. Not decades after I am gone. At 10 knots 5000 hours is 50,000 miles. Luggers will last three times that long. I will be long gone and have paid to install and haul around all that weight in one of the Geena's. I suppose its the fact that you own one that counts though.
     
  13. Willallison
    Joined: Oct 2001
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    Location: Australia

    Willallison Senior Member

    Hmmm.... an interesting quandry... and one where I find myself at odds with the choices I myself would make....
    Richard, you have quite rightly pointed out that a vessel of this type ought to have completely redundant systems - yet the one that is relied upon the most - the engine - you would happily forgoe that redundancy....
    As I said, I am at odds with myself here, for I too would opt for a single, slow revving screw with CPP, if for no other reason than the increased efficiency.

    I disagree with Daniel in his suggestion that deep draft is preferred. That may be true whilst a vessel is offshore. But even a pleasure craft that will spend a lot of time offshore, will spend a lot more time cruising closer in. Unrestricted draft will certainly restrict potentioal cruising grounds.

    What all three of these threads display above all else, is that there is no one right answer. The correct solution for one SOR will be intirely different to another. It is in many ways a reflection of the Option One thread.... different solutions are required to solve different requirements.
     
  14. tunnels

    tunnels Previous Member

    twin engine , both non turbo , Less things to go wrong the better and more reliable . Turbos have a habit of dieing at the wrong time and if the bits go into and through the motor theres a lot of dammage !! twins very rarely both break down at the same time so you could get to a sheltered anchorage some where . :p
     

  15. Brian@BNE
    Joined: Jan 2010
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    Location: Brisbane, Australia

    Brian@BNE Senior Member

    Just a keen amateur dreaming along with you guys, but if I did have the money...

    1. yacht - twin. As shallow a draft as can be reasonably obtained is important for those wonderful places in the tropics at the end of the passage.

    2. trawler - single, due to Richard pointing out impact of twins on accommodation. I accept that for high latitudes, this is the way to go.

    Given I'd want to be in the tropics quite a bit I might need 1 of each ..... dreams are getting big now!

    Richard, are you able to comment on Pierre's question regarding twin CPP's?

    Thanks - Brian
     
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