Buccaneer 24 Trimaran

Discussion in 'Multihulls' started by Samnz, Dec 1, 2008.

  1. bruceb
    Joined: Nov 2008
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    Location: atlanta,ga

    bruceb Senior Member

    wave making

    A few years ago I was staying on board a 200,000lbs+ motor sailor moored at the end of a dock in Sydney harbor. When one of the fast catamaran ferrys came by, there would only be a few inch high wake on the surface, but a shock wave would hit us and raise us 1-2 inches straight up. The water was displaced, and it had to go somewhere even if you didn't see it. Strange feeling though. Bruce
     
  2. bruceb
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    bruceb Senior Member

    dagger board

    Samnz, What sort of dagger board are you using? Bruce
     
  3. bruceb
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    bruceb Senior Member

    Float volume

    Has anyone calculated the volume of a stock buc 24 float, and what should one weigh when new and dry? Bruce
     
  4. Samnz
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    Samnz Senior Member

    I have never fully calculated it but its approx 1000 L.

    My floats which are fully 4mm ply and cedar stringers with a light dynel cloth weigh 75kg each.

    My centre board is currently 2m x 40mm x 400mm not sure on the foil section as its secondhand and very heavy, around 10 kg.

    Its in a vertical case I think (from another thread) was retrofitted around 1990.
     
  5. bruceb
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    bruceb Senior Member

    Thanks, I think my floats are about 100 kg, they are 1/4 inch fir ply with the decks glassed, and may be a little wet. I had guessed the volume around 1100 L, so we are in the same range. I guess "new" theory would make them 22-24' long and about 1600+ L, but that seems really large to me. Your board is a little larger than the one I am working on, but I would have to change the trunk to use one like yours. 20kg doesn't seem too heavy for that size board. Bruce
     
  6. Samnz
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    Samnz Senior Member

    I have devised a very simple system for airing out the floats, keeps them bone dry inside, will get some pics for you. Its importaint to keep air flow in a timber enclosed space I think to prevent mould and rot. Even tho my floats are fully sealed inside with everdure it still worries me!

    At the bow just in front of the beam there is a 1.5 inch skin fitting with the thread poking upwards. I have two fittings for this thread, a cap, and a 90 degree hose tail. On the mooring I put the hose tail on pointing forward, when sailing I put the cap on.

    At the aft end I just remove the aft most inspection port lid and sit a solar vent in the hole when not sailing.
     
  7. basildog
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    Location: Gold Coast Australia

    basildog basildog

    Samnz
    The centre board in your boat was built by Phil Atkinson in Keri Keri for me when I owned the boat. I feel he just went by feel regards shape etc. The day it was fitted was prior to a Wednesday night race and the performance improvement was huge over the original short aft sloping board
    Tony
     
  8. Samnz
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    Samnz Senior Member

    Hi Tony, thanks for the info, I have been meaning to PM you for more details about the case construction.

    I have actually just replaced the board it came with with a very similer but 10mm narrower slightly smaller chord and slightly longer, with a slightly higher speed foil shape, as the board it came with was in very bad shape when I bought the boat.

    Do you know much about the rudder and case? it self destructed the first time we hit 17 Knots :eek:
     
  9. bruceb
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    bruceb Senior Member

    Boards and rot

    I am interested in any board and rudder info; I am making new ones now, thanks guys. I have just ordered a pair of solar vents- I know I need them, thanks for reminding me. I have found several spots of rot in the upper parts of my floats, the decks are epoxy/glass covered and don't seem to leak, but the condensation is way too much. I already have removable 3" cowl vents fore and aft, but I don't know if the previous owner really used them- the solar vents help almost any boat. Bruce
     
  10. oldsailor7
    Joined: May 2008
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    oldsailor7 Senior Member

    When I removed the fixed fin from the bottom of my Buc 24 in the spring of 1972, I replaced it with a daggerboard.
    I can't remember the exact dimensions,--but it had a rectangular planform with an accurately shaped 8% supersonic airfoil section.
    The bottom end was blunt, so that when the board was fully retracted it faired with the bottom of the keel.
    Top and bottom of the box was masked with a fibreglass seal which closely followed the section shape of the board.
    I do remember that when the board was fully down the exposed blade had an aspect ratio of 3:1, so it was probably something like 300 x 900mm and about 25mm thick.
    It was very quick and close winded, not just because of the board, but also because I built the boat with the MK2 Cabin length--but the MK1 cabin width.
    This enabled narrower jib sheeting angles, which combined with the new board made the boat so good on windward courses. :D
     
  11. bruceb
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    bruceb Senior Member

    daggerboard

    Oldsailor, I am building a new board this winter and planing on using it in the existing trunk so I am limited to about 30 mm thick and a cord of 350 mm. I will make it long with tapered tip. (I have made a blank so I know it fits). I have naca 8.5% pattern that looks about right. I may change the trunk later, but right now I am only making a board and rudder. Did your board retract through the cabin top? If I have more time I am going to "mess" with the floats, mine need some work and I think I will get the most gain with them. Bruce
     
  12. tatoski
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    Location: Manila, Philippines

    tatoski Junior Member

    Daggerboard

    Is it possible to do it like the arrangement of the Farrier 22. The board goes out of the cabin. For the Buc 24 is it possible or will it hit the mast or step. I believe it'll be easier to pull it out from the cabin top compared to from the inside because of better leverage. I also get a little seasick when I'm belowdecks.:eek: A daggerboard operated from the cabin top will also allow the board to dimensioned optimally because of the freedom in length not being limited by the cabin height. But I guess this might make it heavier. Well, design is really a compromise.
     
  13. bruceb
    Joined: Nov 2008
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    Location: atlanta,ga

    bruceb Senior Member

    Raising the board

    The way the buc 24 is designed, the mast step gets in the way of the board forward, and would require major mods to change, but easy enough if building new. A long board would have to exit through the cabin top and is only limited by boom clearance if you want to sail with the board up. I don't have a cabin, so it is not a problem for me. I just wondered how other boats were dealing with it. The daggerboard I am building will be just over 7' total with 5.5' exposed with it all the way down. I have done quite a few calculations on shape and size, but the final size was determined by the nice cedar board I found. Bruce
     
  14. tatoski
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    Location: Manila, Philippines

    tatoski Junior Member

    Thanks for the advice Oldsailor. Normally I build the boats according to plans but in the case of Buc 24 with the known and proven mods I guess I'll incorporate a few of these mods for a little more performance. On the other hand I'll be sailing her on a lake and do occasional coastal cruising with my wife and kids and might not require these mods. Is the Buc24 originally designed as a racer or as a cruiser or both? Thanks

    Tatoski
     

  15. oldsailor7
    Joined: May 2008
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    oldsailor7 Senior Member

    The board I described in my post#40 above, was arranged vertically with its centre of area in the same horizontal position as the board shown on the plans. This takes the top of the board box well away from the mast bulkhead and further back in line with frame #5. The top of the board box was inline with the top of the cabin seat and stoutly braced to the mid stringer on each side. I used two pieces of 1" x 12" which then forms a convenient seat for the cook facing the galley. The board had a cap on it so it can't go any further down the boardbox than designed. When the board is down (which it is most of the time) it is quite unobtrousive.

    Bruce, I have to ask you. Why are you making your board so long.:?:
    It is only necessary for the exposed part of the board to have an area of 2% of the projected sail area, (main + foretriangle). More is unnecessary drag and weight. The board section shown on the plans aproximates to NACA 63-010--with a slightly thicker trailing edge (for strength).
    A rectangular plan form is simple and effective on a small boat like this.
    An elliptical planform is a little more efficient, but the board has then to be tapered in thickness toward the tip to maintain the T:C ratio, otherwise the extra efficiency is not realised. Also when sailing with the board in a partly retracted position, board box turbulence occurs. :eek:
     
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