A bluewater, ocean going water ballasted matorsailer. Why not?

Discussion in 'Motorsailers' started by xarax, Jul 23, 2009.

  1. apex1

    apex1 Guest


    Be sure it is a photo Stu! And if you go one page back you will find more info.

    And I do´nt think it was only one high scored member to wipe Xarax´s points, when you have followed the thread you could have seen there have been several completely disagreeing. Me included.
     
  2. xarax

    xarax Previous Member

    I was refering to the highest authority on heavens,,,:)
    I agree !
    The hull I see is a semi displacement, beamy, flat aft, quite fast type of hull, and the righting moment of the boat, when upside down, comes from the form instability in this position, instability that is due to the raised deck house.
    Everybody prefers effective, passive, simple systems when is immersed in an unstable environment, such as the surface of the sea. But I think that in a sailing vessel, where we should not ignore windage, we can not achieve self righting by any other means * except a combination of a raised-as-low- as-possible deck house AND water ballast.
    See the righting moment of the 47ft MLB at page 15 of:
    http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA247184&Location=U2&doc=GetTRDoc.pdf
    * ( If we do not want to use even more complicated and unreliable systems, as automatically inflated air bags, for example.)
    Now, if one gives me a self righting system that :
    1. manages to flip the upside down hull in less than, say, 1-2 minutes even with the sails on and centreboard down
    2. does not load the semi displacement hull as much as a lead keel does. and
    3. does not use water ballast,
    I will drink every drop of this dirty water ballast and forget all about it, I promise !:)
     

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  3. ancient kayaker
    Joined: Aug 2006
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    Location: Alliston, Ontario, Canada

    ancient kayaker aka Terry Haines

     
  4. apex1

    apex1 Guest

    Live with it, nice thoughts no result! And that has nothing to do with being overly conservative or thinking oldfashioned.
    (conservative we have to be, we are responsible for the lives at sea, adventureous games have no place in our business)

    It is just a tested and proven fact, water ballast is nonsense in a bluewater boat.

    And you will definetively not change that, no matter how many attempts, no matter which way round you try to solve a non existing problem. See it so:
    Your Porsche is not the best performer, Whooshs Mondeo wins the trophy, when my refrigerator has to be transported.
     
  5. xarax

    xarax Previous Member

    I was replying to a remark of Pierre R. about mathematical equations. I should have said that we do not have complete, mathematical knowledge, not yet, and this is the meaning of the words of Leo Lauzauskas. Knowledge is a very wide word, a truly planning word on the semantic sea! Most of our knowledge still comes from crude experiments, and past experience. This is not the kind of scientific knowledge Pierre R. suggests that is excluding wide semi displacement water ballasted hulls from been used on blue water boats. I am sure that even in the case of testing very sophisticated vessels, as these lifeboats, when they perform their final tests on them, the chief engineers are holding their breath and their fingers crossed! It needs only a frozen O-ring to kill all people aboard a complex vehicle......
     
  6. ancient kayaker
    Joined: Aug 2006
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    Location: Alliston, Ontario, Canada

    ancient kayaker aka Terry Haines

    ... that would be the moderator in this context :)

    -me too!

    I strongly disagree with the entire concept of negative points.
     
  7. Pierre R
    Joined: May 2007
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    Location: ohio, USA

    Pierre R Senior Member

    Xarax the equations may not be exacting science but they do point you in the right direction. I can come pretty darn close on what to expect at semi displacement speeds out of a boat.
     
  8. xarax

    xarax Previous Member

    Well, it looks quite beamy to me, compared with the hull of a traditional motorsailer, or of the slender hull of a motorboat like this :
    http://www.rangeboat.com/index.php
    designed by Nigel Irens. And when I say fast, I mean faster than the pure displacement speed. the 47 ft MLB travels at around 25 knots,
    http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA247184&Location=U2&doc=GetTRDoc.pdf ( see also its righting moment / heel on page 15 )
    so does the 52 ft "trawler" like Beneteau, but the traditional Nordhavn 57 motorsailer, (that costs a fortune), drags its old lead foot at 9 knots !
     
  9. xarax

    xarax Previous Member

    As I have said earlier, if we want specific numbers we have to look at specific existing boats and figure out the market and engineering window.
    The Beneteau Swifttrawler 52, the Nordhavn 56 MS and the 47 ft MLB of the US Coast Guard are completely different vessels, but of similar dimensions of what concerns us here. So :
    1a) Speed under power : This is entirely unknown at this phase. We want a semi displacement, quite beamy hull (with large wetted area compared to a sailboat), to be propelled by a rig of low centre of effort, ( because our water ballast system would be less efficient than a lead keel ), so probably a schooner rig , or any other two mast configuration. Speed under sail and windward ability are of less importance than:
    1b) speed under power. Now THIS is the fill or kill order of the whole idea. The above mentioned fast boats move their 50 ft and 20 tons at around 25 knots.
    2) Range under power : As a motorsailer that can also use its sails, the range under power is of less importance than in the case of a passagemaker, a trawler or any other type of bluewater motorboat. 1000 miles at 9 knots, or 500 at 18 knots would be fine, I guess.
    3) Trans Atlantic voyager, needs to handle conditions that can not be predicted by weather forecast and avoided by sailing away.
    4) Self righting from a rollover in 1-1,5 minutes maximum.
    5) Length : 50-60 ft LOA
    6) Draft : 1.5 m
    7) Beam : 5 m
    Living accommodations for 2 couples,owner + guest, a captain and possibly 1 crew member.
     
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  10. Stumble
    Joined: Oct 2008
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    Stumble Senior Member

    Xarax,

    Buy a Bertram 510 and stick a 30' carbon fiber rig in the boat (Melgeus 24 rig should be about right). Since you don't care about sailing characteristics, then this is just another semi-planing hull power boat with a get home/stabalizing rig onboard. Then add a swing down dagger board and oversized rudder and be done with it.
     
  11. xarax

    xarax Previous Member

    Stumble,
    Would you manage to hold it upright with the 'sail"'of your ( water ballasted AND self righting ) Unterseeboot ( and apex1 on helm ), or do I have to install a little nice water ballasted self righting system on board of my Bertam instead ? :)
     
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  12. Guest62110524

    Guest62110524 Previous Member

    yes was ONE, I posted Xarax,(who got under your skin) pos, he was 26, next second he was 2, I know from where that came, and he should be very ashamed
    XARAX ranks as one of the most intelligent men I have ever met, he was testing you guys and he won hands down, he was never vulgar or rude as you yourself were
    HE may not be the brilliant rocket sci , but he is far better than me or you
    he offered me his beach home, for free, and I have known him a long time
    i feel humbled in his presence, on the other hand many (high pts people) have yet to earn my respect
    Tom Speers, Ric, ancient kyakkerr, Guillermo, Matt, Mike J, all have that respect
     
  13. john.G
    Joined: May 2006
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    Location: australia

    john.G Junior Member

    water ballast ... motor ... sails ... self righting ... easily modified to class 3A requirements ... and I like it!!!

    http://www.dixdesign.com/cargo50.htm

    Oh yeah, it can't be done right?!?!
     
    Last edited: Jul 30, 2009
  14. FAST FRED
    Joined: Oct 2002
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    1000 miles at 9 knots, or 500 at 18 knots would be fine,


    More likely to be 200 miles at 18K, IF that's acceptable , your task is easy.

    FF
     

  15. Pierre R
    Joined: May 2007
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    Location: ohio, USA

    Pierre R Senior Member

    Xarax what kind of speed are you looking for under sail?
     
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