12 Metre design

Discussion in 'Sailboats' started by phum, Oct 14, 2009.

  1. gonzo
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    gonzo Senior Member

    The why is to beat a rule. If you can make a boat that measures slower than it actually is, you beat the rule and win races. It doesn't mean the boat is faster, but that the rule says it is slower.
     
  2. Paul B

    Paul B Previous Member

    Like this one?
     

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  3. Paul Kotzebue

    Paul Kotzebue Previous Member

    That's the one I was thinking of. Designed around 1960 and looks more towards the RORC than the CCA rule. Does not have a bustle at all, which is one of the reasons it is such a nice looking boat. Wouldn't mind owning a boat like that myself.
     
  4. PAR
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    PAR Yacht Designer/Builder

    I've had two, a 1960 copper riveted teak version and a 1968 'glass one. The 'glass version had the bustle, though the pictures from the owners group I just looked at didn't show the same thing, so it must have been a previous owner modification. It surely was very well done if that was the case. I don't remember the rudder port area on the '68, though I remember the teak one, which needed extensive bulkhead repairs. It was one of my favorite sailing boats.
     
  5. Paul Kotzebue

    Paul Kotzebue Previous Member

    Beautiful boats.

    To get back on topic, I still think the only reason for a bustle is to minimize measured length in a rating rule where length is measured between girth stations, such as the IOR and International Rule (meter classes). I am interested to know if designers such as S&S and Bill Tripp, Sr. were using bustles to optimize boats during the CCA era (pre 1970) as was implied in an earlier post.

    Sailing yacht design innovations should be studied in the context of the rule they were measured under.
     
  6. booster
    Joined: Apr 2009
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    booster Senior Member

    2.4mr

    Phum and Kotzebue!

    True, in the context of the rule. The 2.4mr designs can be studied at

    www.24mr.se

    Regards,
    Booster
     
  7. phum
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    phum Junior Member

    Dskira,
    Answers to your questions.
    I have freinds who design, build and sail A. Class radio controlled model yachts.
    It surprises me that with all the variation in underwater profiles there is not much difference in performance.
    I would like to know how bustles affect water flow and performance etc.
    It can't be all cheat, there must be some science behind it.
    Peter
     
  8. phum
    Joined: Apr 2009
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    phum Junior Member

    Booster,
    Thanks, I note the modded one with the Mariner type stern.
    I sent a couple of emails to addresses in that site but no responce.
    Peter
     
  9. apex1

    apex1 Guest

    Yeah it is of course! Did nobody notice that the designer was pretty drunk when he drew the rudder? That rudder does well under sail, under power you nearly have no rudder. Maneuvering with such a hole on the wrong side is a pain in tight quarters.
     
  10. Paul Kotzebue

    Paul Kotzebue Previous Member

    Apex,

    That rudder is typical of auxiliary sailing yachts built from the 1930's through the 1960's. I've sailed on many boats with that type of rudder. They did not maneuver well under power, but you went real slow in tight quarters. It was just about as easy to maneuver those boats under sail as under power. The idea was to hide the propeller behind the keel under sail. The aperture extending into the rudder allowed the propeller shaft to be removed without removing the rudder.

    phum,

    The reason you don't see bustles on every boat is they do not make a boat faster. They are a means of reducing the measured length under certain handicapping rules, and that's it. It can make the difference between winning and losing so it is important. The IOR bustles of the early 1970's all but disappeared by the end of the IOR era in the late 1980's. All the science and tank testing involved with the design of bustles was to optimize actual speed vs. rated speed. For a given rated length, the bustle would decrease wave making resistance at certain speeds. That's the crux of the science.

    Booster,

    Cool stuff on the 2.4m site. Lots of little bustles that end just forward of the aft girth measurement station.
     
  11. Paul B

    Paul B Previous Member

    I've never seen a bustle on any boat that was not there for a rating consideration, as you have pointed out.

    For the supposed bustle on a Lion 35, if it was added as an addition to the outer skin that would be easy to spot as the visible bump on the hull would not have a corresponding void inside the hull. Back in the late 1960s/early 1970s I doubt an addition would have been done this way.

    If it was integrated into the existing glass hull the surgery would have been significant. Probably the last 1/4 to 1/3 of the hull below the WL would have had to have been removed, then rebuilt over new forms. This would have required a significant portion of the interior to be removed and later rebuilt. The surgery would have left visible laminate changes on the inner skin. That's something you couldn't miss.

    I can't imagine anyone spending the time and money to make that sort of a change, one that would not make the boat sail better or rate better. It makes no sense.
     
  12. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    I can and have seen this level of "significant change", the last being a bow extension to compete in the Bermuda race as a 40' yacht with a 37'er. As to the bustle, I just can't remember that portion of the hull, internally, it was about 30 years ago now. I suspect the 'glass version of the Robb design was just a knock off, though the spec's for the two different hulls show different LWL lengths. This suggests displacement was "accommodated" in the 'glass version. If this is the case, other "modifications" could have been incorporated into the mold. My dealings with Choy Lee when I owned the 'glass version of this yacht (mid 1970's) discovered that a fire destroyed most of the records and drawings from earlier production runs. They sent what they had and were surprisingly helpful with what information was available. Of course Robb's wooden drawings were easy to get. I don't even know if Robb drew up the 'glass version or authorized the conversion.
     
  13. Paul B

    Paul B Previous Member

    What boat was it that added to the bow in this way? Of course there was a surely a reason for this, such as length restriction to enter the race? Many boats have significant mods, but there is a reason. Adding a bustle to a Lion 35 has no reason.


    Surely you have photos of that boat?

    I imagine Cheoy Lee produced the glass mold from the same lines as the wood boats. Probably even used a wood hull to splash the mold. Regardless, I can't find any evidence of any glass hull having the bustle described.
     
  14. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    What is it with you, do you find it necessary to call most of the forum member liars or is it that you just are one of those argumentative persons that must find fault with everything.

    Just because you don't understand something, doesn't mean it doesn't exist, it just means you don't understand it.
     

  15. Paul B

    Paul B Previous Member

    Sounds like someone is projecting here. Why do you have lies at the forefront of your thoughts?

    I have not said anything about a lie. You claim something, and I asked if you had a photo, since my recollection and all evidence I can find on the internet don't show anything like it. If we knew things like Hull Number or registration we could look into it further to try and understand it. It would be interesting to see the modification you describe.

    Ditto the question about adding to the bow of a boat. Sounds like an intersting solution to a problem.


    There are many things I don't understand, therefore I ask questions.
     
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