Daggerboards vs keeled hulls

Discussion in 'Multihulls' started by nickvonw, Apr 11, 2011.

  1. CatBuilder

    CatBuilder Previous Member

    This can go in circles for days, but I'd like to point out that a dagger board that hits something and is broken is far better than a keel that is broken the same way. It can be repaired while under way. No haul out even required.

    Michael, it sounds like you are coming at this from a monohull mindset. Things work differently on cats. Dagger trunks have impact absorbing, replaceable, foam crash blocks in the trunk, if built properly. There is no trunk damage.

    The boards are the deepest thing when fully down. Rudders kick up on impact.

    Like the poster above, ill have outboards with this setup. A perfectly workable and better performance setup than keels with no damage to motoring gear possible, as it retracts.

    Only downside is the loss of interior space as we see in that galley layout thread.
     
  2. Steve W
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    Steve W Senior Member

    Catbuilder, you cant pick calm conditions when a boat is on a mooring, its more as Michael described in post#14, and yet i have seen many keel less multis drying out this way through calms and storms,year after year.
    Steve.
     
  3. CatBuilder

    CatBuilder Previous Member

    That's true, Steve.

    I've seen the same, too. I was coming at it from a cruising perspective. Guess we all have a perspective. :)
     
  4. CatBuilder

    CatBuilder Previous Member

    That's true, Steve.

    I've seen the same, too. I was coming at it from a cruising perspective. Guess we all have a perspective. :)
     
  5. michael pierzga
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    michael pierzga Senior Member

    Im not a multi guy but Ive been around long enough to understand that all design features have advantages and disadvantages. If youre aware of them...then as they say... the customer is always right.

    Concerning daggerboards or centreboards...I know them well having spent many nights lying in my bunk, listening to them clonk back and forth at sea. I would gladly retard windward performance to create an easy to use, easy to live with boat.

    Im sure that a daggerboard will give better performance but as I look at the multi hull fleet of cruisers, I see that a majority have long fixed keels.
     
  6. michael pierzga
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    michael pierzga Senior Member

    Oh and Cat...concerning grounding and rudders. Kick ups work as designed when the boat has forward motion. The typical grounding I experience is backing into a stern too, lines ashore to the rocks, anchorage or at anchor in a confined bay. No forward motion. Even when You depth survey the anchorage, set the hook correctly in deep water , you simply do not know the bottom profile in your anchor swing circle. A change in current set or wind direction swings the boat and backs your rudder into the reef. A very good device to alert you that you are swinging into shallow water is a stand alone, aft facing, depth finder with alarm.
     
  7. CatBuilder

    CatBuilder Previous Member

    Uh, smart cat owners kick the rudders up at anchor to avoid growth, so they don't ground Luke that while swinging. However, I can certainly see it being an issue stern to. As an American, I haven't been fortunate enough to cruise your area yet, so haven't ever tied up stern to. Looking forward to it though! Never been to Espana by sea.

     
  8. Alan.M
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    Alan.M Junior Member

    If you hit something going backwards, kick up rudders may not be of much help - but then fixed rudders will be no better will they? Neither will mini-keels help.

    However as stated above - when I'm not sure of the depth of the my entire swinging circle, I lift the rudders.

    Actually, being able to lift rudders and daggers has a few benefits I didn't expect. In current affected anchorages I can lift the rudders and dagger and the boat will lie to the wind moreso than with them down. ThisCan improve ventilation greatly.

    In anchorages where a swell causes slapping under the stern, lifting the cassette mounted rudders will greatly reduce or eliminate it.

    To be honest, having had them, I wouldn't go cruising on a boat where I couldn't lift foils and rudders.
     
  9. rayaldridge
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    rayaldridge Senior Member

    Michael, you may not realize just how important windward ability is to a fast multihull.

    Also, the reason you see so many cats with keels is that many larger cats are built for the charter trade. These boats are not performance-oriented-- they are more concerned with cost and simpliicity of operation-- and keels do win on those points.
     
  10. CatBuilder

    CatBuilder Previous Member

    And really, not to mention the safety issues.

    Most monohull sailors I know would say that it is *very*important for a cruising monohull to be able to claw its way off a lee shore in a gale under sail alone.

    With dagger boards, you'll be able to do that. With mini keels? Maybe... but probably not.
     
  11. hoytedow
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    hoytedow Carbon Based Life Form

    Question; Though a daggerboard is a foil that catches junk, isn't that junk fairly easily released by simply raising the daggerboard?
     
  12. rberrey
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    rberrey Senior Member

    I hope so. rick
     
  13. michael pierzga
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    michael pierzga Senior Member

    Sure.... just pick them up. problem with daggerboards is that they are perpendicular to the hull....they pick up and hold junk and are fragile .

    As far as beating off a lee shore....well...first stay off lee shores and then keep you powerplants in order. I almost always gain searoom by striking the genoa and motor sailing.

    Windward performance is valuable for cruising in confined waters when the ability to hold high gets you to windward of an obstruction allowing you to avoid a few tacks.

    In the end its up to the customer. carry those fragile, intrusive, expensive boards around for the next twenty years or accept reduced windward performance. Everything on boats is a comprimise.
     
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  14. Contorta
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    Contorta Junior Member

    Jim Brown's Searunner series trimarans are/were designed with a replaceable 'wormshoe' around a pivoting centreboard. The 'wormshoe' spanned two main bulkheads and I think the concept merits consideration around daggerboards as well. They could be made thick enough to keep fragile hulls out of harms way.
     

  15. rayaldridge
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    rayaldridge Senior Member

    There's actually no need for daggerboards to be perpendicular to the hulls. In addition, they can be offset from the centerline, and even tilted to slide through a case built against the topsides, so that they take up little interior space. A single daggerboard will suffice for a cat,

    The problem with inferior windward performance for fast multihulls is that such boats are fast enough to bring the apparent wind forward to a much greater degree than is the case with displacement monohulls. This is the reason that windward ability is so important-- much more important than for slower boats. In a breeze and course on which a slower monohull will be reaching, the fast multi will be hard on the wind.

    The extra draft unavoidable with keels is a detriment to the safety of the vessel in more ways than one. For one, in breaking seas, the daggerboard boat will be safer, as it is less apt to trip over its keels. In a daggerboard boat, the boards can be retracted, and in breaking seas, the boat will surf sideways, rather than digging in and potentially capsizing. In seeking shelter from bad weather, the ability to put a shallow draft boat deep into the mangroves, or up shallow creeks, rather than remaining in the more exposed anchorages required for a deeper draft boat... that's a huge safety factor.

    As others have mentioned, reinforcing the hulls so that the boat can safely take the ground is easy to do in a number of satisfactory ways.
     
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