Drop keel using boatlift

Discussion in 'Sailboats' started by Windvang, Jun 12, 2014.

  1. Windvang
    Joined: Jan 2006
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    Location: Rotterdam,The Netherlands

    Windvang Yacht Designer

    I would like to use a dropkeel without its own lifting system. The boat will always be launched with a boatlift and my idea is to lower the hull over the keel on its trailer using the power of the boatlift and vice versa. It will of course be securely fixed in its lowered position.

    Does anybody have experience with this or know a design that uses the shoreside crane/boatlift to "retract" the keel?
     
  2. laukejas
    Joined: Feb 2012
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    laukejas Senior Member

    Interesting idea - how much would that keel weight? I never seen anything like this, but my first though - if the only way to raise keel is to lower boat on it's trailer again (if I understood correctly), it would limit shallow water sailing possibilities, as well as launching options.

    What if boatlift keel drop would be the prefered way, but the boat would also have auxiliary option to raise/drop keel, for example with winches (with some sort of reduction system)?

    Or at least the keel could be also locked in the raised position, and then dropped slowly when on water.
     
  3. Windvang
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    Windvang Yacht Designer

    This boat will always sail on deep water, it is just for road transport and storage as the owner lives in the middle of Germany. You could however include a stopping device partially raised if you want to sail shallow waters. It is a 730 Kg keel with a T bulb.
     
  4. laukejas
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    laukejas Senior Member

    Well, if that's the case, then I guess it's okay. If I were to do such project, I would consider if trailer should have some kind of padding where the keel bulb touches the trailer. Considering bumpy ride when transporting the boat, as well as the weight of the keel and it's partially loose configuration, I guess something could get damaged.

    Maybe I'm wrong about this, maybe it's not an issue. Let's hear more experienced opinions.
     
  5. gonzo
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    gonzo Senior Member

    It seems like a complicated system for a fixed keel. Also, the interior box necessary to house the keel will take a lot of space. If you have the capability of lifting the boat, a bolted on keel would simpler, take less interior space, less noise (from rattling in the box)
     
  6. Windvang
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    Windvang Yacht Designer

    I agree a fixed simpeler. The owner however has to drive 4 hours with his boot on a trailer to the nearest open water, sometimes trough the mountains. And trailering the boat low in your rearview mirrors is much nicer, safer and less full consuming than 3.5 m up on the trailer.

    The keel will be locked down with stainless bolts and fit between Delrin side plates. Similar constructions we used made no noise at all.
     
  7. SukiSolo
    Joined: Dec 2012
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    SukiSolo Senior Member

    Surely there is a neater solution. Make the trailer itself become the hull hoist ie raise the hull, then place keel underneath and drop on to keel for a bolt up session. As long as the meams to manoevre the keel to somewhere on the trailer that is OK it ought to work. This keeps it independent of any shoreside facilities too. Agreed the trailer is more expensive but simple pivots are almost all that are needed.
     
  8. gonzo
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    gonzo Senior Member

    With a full keel, the boat will need a lift anyway. Otherwise, the trailer needs to be in 5-6 feet of water before the boat floats off.
     
  9. Stumble
    Joined: Oct 2008
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    Stumble Senior Member

    Once you accept the difficulty of being able to lift the keel, it doesn't take that much more to be able to lift it with onboard equipment. Smaller boats like the VX do it with the mast, larger ones like the Melgus 32 use a simple crane bridging the keel sump.

    I am just not sure why you wouldn't make it integral to the boat.
     
  10. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    If not willing to make the keel retractable internally, why not just make it detachable and toss the bother of a case and hoisting system. Using a travel lift as a means of raising or lowering the appendage, isn't especially precise. I can easily see a travel lift snapping off a fin by lowering too fast or not "feeling" a bind, before it jams up tight. Lifts are pretty clumsy in this regard, with binding/jamming a very likely possibility. A lifting keel isn't very easy to engineer and exspect it to work properly every time, unless you have considerable engineering experience, but a detachable fin is a much easier set of problems to solve.

    First of all, what boat is this (year, make and model), so we can know what you're looking at. I agree with Greg, in that an internal lift is just as practical as using a travel lift and certainly much more precise. You do have a case to contend with, but welcome to the compromises of yacht design.
     

  11. messabout
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    messabout Senior Member

    A simple, inexpensive, trailer winch can haul up a considerable weight. Mounted to the case, it can lift the board or let it down if the case is sufficiently robust.

    Sooner or later there will be a circumstance when the ability to lift the board a bit will be a trouble saver.
     
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