Pocket cruising boats

Discussion in 'Sailboats' started by Guillermo, Apr 30, 2006.

  1. Angélique
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    Angélique aka Angel (only by name)

    The thread started with a much wider view as for only yachts under 8 m and categorised as A or B category within the EU RCD requirements. This narrowing of interest started in post #161 were it was the first time a RCD category was mentioned on this thread.

    For those still interested the original thread intent see the bottom links of this post for a lot of boats from 20' up were most, if not all, are able to qualify as a candidate for the EU RCD requirements in category A or B. Many on the list are under the 30' starting point of the thread, and some of them (the Flicka 20 and Nor'Sea 27) are already discussed on this thread.

    For more see: Blue Water Boats ---> List
     
  2. Guillermo
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    Guillermo Ingeniero Naval

    KOALEN 26 designed by François Vivier, is a B categorized 7.95 m boat:

    http://vivierboats.com/html/stock_classic.html#koalen26

    It is interesting that the first Vivier's design reaching category B is precisely this almost 8 m long boat. Under that length Vivier's designs only reach Category C.

    [​IMG]
     
  3. Guillermo
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    Guillermo Ingeniero Naval

  4. Guillermo
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    Guillermo Ingeniero Naval

  5. Guillermo
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    Guillermo Ingeniero Naval

  6. Guillermo
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    Guillermo Ingeniero Naval

  7. Angélique
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    Angélique aka Angel (only by name)

    What does the addition ‘‘ - 6 ’’ mean in the category . . ? ?

    It looks that like the Wadkrabber (in post #170) the Deltania 25 also can be build in C and B category, and they also use a ballasted centreboard, in their case 100 kg, perhaps this is like the Wadkrabber to move from C to B category . . ? ?
     
  8. Angélique
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    Angélique aka Angel (only by name)

    Also noteworthy is that the daggerboard version (the lightest of the four) reaches the B category, perhaps this one has her ballast in a bulb below the daggerboard, and the heavier centreboard version has her ballast inside on the bottom . . ? ?

    It would be interesting to know what makes the difference in categorization between those two . . :idea:
     
  9. Angélique
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    Angélique aka Angel (only by name)

    BTW, are the calculations for the CE categorization always done with the board down . . ? ?

    If so, then the boat would be in a lower category when a ballasted board is up I think . . :confused:
     
  10. Guillermo
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    Guillermo Ingeniero Naval

    The number after the C and B letters are the allowed crew for that category, I think you have already figured that out.

    Deltania 25 has two versions, one with the 100 kg centerboard and the other with the 385 kg ballasted fixed keel, being this version the one reaching category B.

    A similar thing happens with the Maxus 26, but the daggerboard B categorization looks very unprobable, beinng this version's displacement the lowest of the four.

    Other things being equal, a lower displacement provides lower righting energy than a higher displacement, so the daggerboard version should have more difficulty to reach a higher category than the centerboard one. To reach at least 54.000 kg.m.deg (área under the GZ curve times displacement) is one of the requirements to qualify in B category.

    A much lower CoG, thus affecting the GZ curve and making its area higher, could be an explanation, but it seems to me to be unprobable.

    A typo?
     
  11. Angélique
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    Angélique aka Angel (only by name)

    Guillermo thanks for the info, I didn't figure that out yet . . :)
     
  12. Angélique
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    Angélique aka Angel (only by name)

    That's what I was thinking (in post #188) by my guess for the ballast in a bulb below the daggerboard and the question in post #189, could you have a look at that one ?
     
  13. Guillermo
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    Guillermo Ingeniero Naval

    Tests to be done with centerboard down.
    No way of reaching a higher category with the board up than with it down.
     
  14. sharpii2
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    sharpii2 Senior Member

    It will be definitely slower than it originally was, but lighter L/D boats tend to have bigger rigs, in proportion to their displacement, than heavier D/L boats do.

    The biggest potential problem could be added rigging loads, but that might be debatable too, especially if the lighter boat was designed with the anticipation of lots of crew sitting on the windward rail. As a BW cruiser there will be no large crew to do this, but maybe just two or three people aboard with at least one of them sleeping (or trying to) while off watch.

    Going narrow can cause problems too.

    The main thing you lose then is sail carrying ability per ballast ratio. The narrower boat is going to need more ballast, deeper ballast, or a combination of the two, if it's to have the same initial stability as the wider boat.

    The narrower boat can compensate by having a shorter rig.

    In windy conditions, the narrower boat will probably be faster, even if somewhat under rigged for its displacement. But in average condions, the wider boat may well be faster. Not only that, but it would have more liveaboard space as well.
     

  15. Angélique
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    Angélique aka Angel (only by name)

    I'm afraid we have some miscommunication here, my above second sentence was the other way around, meaning would the boat be in a lower category when the calculations were done with a ballasted board up ?

    If so, then the higher CE categorization calculated with a ballasted board down could be only theoretical when the board is up I think, since the board isn't always down, and there are situations like when lying ahull where it's better to have the board up and slide sideways by the impact of waves rather than trip over the board.
     
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