Pivoting keel ideas?

Discussion in 'Sailboats' started by Roo2, Sep 8, 2014.

  1. mirkosebastian
    Joined: Feb 2012
    Posts: 21
    Likes: 10, Points: 3, Legacy Rep: 28
    Location: Hamburg

    mirkosebastian Junior Member

    Garage door spring along the comp'way, interesting idea.
    I gunkhole with my cabin dinghy. The wooden centerboard pops up, when hitting a rock or the frame of the trailer going up, a big plus single-handed. But no ballast...
    Before the 40kg steel board would hit hard and stop the boat, things then got out of control.
    A spring loaded ballast-board that pops up say 30cm would do the trick.
  2. mirkosebastian
    Joined: Feb 2012
    Posts: 21
    Likes: 10, Points: 3, Legacy Rep: 28
    Location: Hamburg

    mirkosebastian Junior Member

    Pivoting bulb on a centerboard: one set-up for lake racing (no ballast class-rules) and another for coastal cruising
    Folks with access to a crane have one wooden board and another ballasted, but swapping boards on the trailer?
    Mounting a bulb seems feasible, specially if the board is off-center and the ballast in segments.
    The stress of the pivot on the board edge is not that high, the lift line might vibrate.

    Attached Files:

  3. rnlock
    Joined: Aug 2016
    Posts: 242
    Likes: 66, Points: 28, Legacy Rep: 10
    Location: Massachusetts

    rnlock Senior Member

    Something small wrapped around the cable in a spiral should cut way down on the humming. There is even oceanographic tow cable made like that to prevent humming. The spiral prevents the vortices from breaking free all at the same time along the length of the cable. I don't know if the oceanographic cable is small enough or affordable, though. The same principle works for humming and vibrating ropes holding something on your car's roof. You can also twist flat straps a few times. And I'm pretty sure it would work for round roof rack bars.
  4. sharpii2
    Joined: May 2004
    Posts: 2,229
    Likes: 310, Points: 83, Legacy Rep: 611
    Location: Michigan, USA

    sharpii2 Senior Member

    A swing keel will likely need to be deeper (and its case longer) to get the same stability without a bulb.

    One way around this problem is to make the bottom of the keel longer and increase the amount of ballast in it. But this means a higher case to house it.

    Another potential problem is that it will be hard to lock in place when lowered, especially when it's not lowered all the way.

  5. gggGuest
    Joined: Feb 2005
    Posts: 864
    Likes: 38, Points: 28, Legacy Rep: 76
    Location: UK

    gggGuest ...

    As the current system is apparently fully effective, is it perhaps worth considering whether a radical redesign of the trailer would be a better way of handling launch/retrieve awkwardness? I've seen quite a number of trailers that might have benefited from the same quality of thought that had gone into the boat they were intended to carry.
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.