Will it tack like a catamaran

Discussion in 'Fiberglass and Composite Boat Building' started by gaza, Feb 23, 2020.

  1. gaza
    Joined: Jul 2013
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    Location: queensland

    gaza Junior Member

    I'm building a 8 metre sports sailing boat
    It has a planning hull. The plan shape is like a bullet with a flat bottom . Ill have a 8 ft long by 12 inches deep by 2 inches thick fin keel weighing around 50 kg and a swing keel of it weighing around 70kg to 100 kg. Full headroom cabin to sleep six .Mast is under size 8 metres long. Not trying to brake any speed records. All normalish so far . Here's the kicker. I want to put a narrow 2 ft 6 inches wide x 20ft long x 1 meter deep outrigger displacement hull between 6 and 8 feet away from the main hull on the port side. The outrigger will be light enough for 2 people to pick up and will be able to slip into the main hulls interior so the whole thing is trailerable .the arms to hold the 2 hulls together will also be packed on th boat .
    The outrigger hull will be used for storage of fuel anchors ect . It may even have ballast set up to pump water in and out depending on the direction of the wind. So why am I doing this??
    #1 I plan to coastal hop to the tropics
    #2 i want to sail flatter like a catamaran
    # 3 good for extra storage
    #4 it will dismantle to tow as a trailer sailer
    Any thoughts on the the performance of this concept ,and wether or not the design will tack like a catamaran would be greatly appreciated
    Garry
     
    Last edited: Feb 23, 2020
  2. BlueBell
    Joined: May 2017
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    BlueBell Ahhhhh...

    Sort of. It will sail more like a proa.
    What's a "planning" hull?
    What's the budget and planned completion date?
     
  3. upchurchmr
    Joined: Feb 2011
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    upchurchmr Senior Member

    We need to see your drawing.
    This sounds like a confused mess of ideas that will be very difficult to get to work.
    A keel on the main hull of a trimaran does not really add to the stability because the main hull does not lean over enough to make the keel give extra righting moment. Just adding weight will do the same.
    How much displacement will you have in the outriggers? Compared to the weight of the boat?
     
  4. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    It is what "planing" turns into when the spelling adjusts automatically !
     
    DogCavalry and fallguy like this.
  5. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

    Have you considered making it a 'proper' proa, rather than what might be described as a monohull with an appendage on the side?
    If so, then I think you definitely want to keep the keel weight to a minimum consistent with providing the required surface area to combat leeway.
    Maybe it is a bit ambitious to have a 'planing' (possibly, in a full gale perhaps?) hull form with a wide transom - most proa types tend to be more double ended.
    The 'full headroom cabin to sleep six' also sounds rather ambitious for an 8 metre long boat, even if it were a cruising catamaran.
     
  6. gaza
    Joined: Jul 2013
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    gaza Junior Member

    It's a flat bottom at the back of the boat a bit like getting a piece of a4 paper and pinching it at one end flaring out to the back if that makes any sense. The main hull is already glassed in 2 420gram double bias and 1 layer of 11oz cloth . No chance of shutting like a Proa if I had a duel rudder one on each hull could I possibly tack.i was hoping the weight of the outrigger would compensate for the the healing.
    Thoughts please.
    If I else fail I'll g o back to the mono design
     
  7. upchurchmr
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    upchurchmr Senior Member

    No drawings?
    Already built the hull?

    Pretty late to worry. Just build it and put up with the way it works.
    The time to consider major features is before you start building.
     
  8. Rumars
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    Rumars Senior Member

  9. gaza
    Joined: Jul 2013
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    gaza Junior Member

    Thanks for the input and photos much appreciated. The hull is an 8 metre sports sailing boat. Ill try to download some photos when I able. Plan shape is like a bullet . It is a design by a A proven boat designer here in QLD. As a mono it will perform
    Well there are many of his boats club racing. I just want to sail flatter and have more storage .
     
  10. gaza
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    gaza Junior Member

    My boat will have only one outrigger. A short mast 8 metres on a 8mtere boat.
     
  11. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    Okay, dumb guy here. I am no sailor; not even a whisper of one.

    Does a proa sail in both directions? That is, does an outrigger canoe or sailboat need the outrigger off the wind?

    I always assumed a single outrigger would prevent the main hull from tipping and so run off the wind. I suppose running to the wind; the ama would be a counterweight, but you would still heel.

    So, for a regular hull; how would that work? Like I said, dumb guy here. Be nice, please.
     
  12. Rumars
    Joined: Mar 2013
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    Rumars Senior Member

    @fallguy
    Shunting outrigger: single outrigger always to windward, boat is double ended and exchanges bow for stern instead of tacking. Outrigger is always used as a counterweight.
    Tacking outrigger: boat can have transom or be double ended but there is a definite bow and stern. Single outrigger alternatively to windward and leeward, acting as counterweight or by buoyancy.

    All outriggers can or will heel, when and how much depends on the construction details. One can put outriggers on "conventional" monohulls but most are trimarans.

    @gaza
    A bullet can be a sphere, round nosed, flat nosed, point nosed, the back end can be straight, tapered, etc. If you want some answers you need to provide at least some of the following: plans, photos of the hull with stats, or designer and model.
     
  13. gaza
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    gaza Junior Member

    Ill get some photos and drawings . And keep you posted
    Thanks again for the advice will take it onboard
    Garry
     
  14. gaza
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    gaza Junior Member

    Outrigger dimensions
    20ft long x 2ft 6inches wide x39 inches deep .will also have a dagger board. Weight not loaded 60 to 80 kg
    Plan to have hatches for fuel water anchors ect around 150kg of weight
    Ballast. I was also toying with the idea of pumping 300 litres in and out for more ballast so when the wind comes In from the outrigger side there will be around 500kg to counter balance .then pump it out when the wind blows from the main hull side. If this makes sense. Thanks again
    Garry
     

  15. gaza
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    gaza Junior Member

    Not possible to make a Proa. Completely the wrong hull shape. Main hull is already glassed. The stern is 2.4 metres wide . So if I want an outrigger I will need to know how to make it work .This is the reason I m on the forum. Where I'm sailing to I need at least 6 people on the boat for reasons I won't explain. the Proa Will be to small
     
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