Alternative to marvelous Buccaneer 24

Discussion in 'Multihulls' started by Gary Baigent, Apr 18, 2010.

  1. Gary Baigent
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    Gary Baigent Senior Member

    Well Tim, I guess you could build any size and length you would like because the larger the chord, the thicker the section, meaning if you were building 100 foot wing mast, just guessing off top of head, the chord would be around 1.5 metres and the thickness around 400mm - the I beam would have to be 5-6mm ply with carbon box weave both sides, the skin could be 4mm plus carbon uni directionals running over the thickest section. This would end up fairly expensive but not as high as foam/Nomex/glass/carbon but the more exotic laminate would be stiffer and lighter.
    The tallest I've built is 15.5 metre x 510mm chord. I'm sure there have been others built taller/larger but can't think of any; if you're going to the expense and effort to construct such a rig, then you'd play safe and go to all exotics. Meaning that with my smaller boats, if rig comes down it's not a big deal to replace/rebuild.
     
  2. DennisRB
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    DennisRB Senior Member

    How about a rig for say a 49 foot performance cruising catamaran of about 8000kg max displacement? Would it be cheaper and lighter to build a rig like this than to build using a regular alloy extrusion?
     
  3. Gary Baigent
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    Gary Baigent Senior Member

    Yes.
    But don't listen to me about the build.
    However, just a guess and I'm sure any engineer worth his high fees would say this is too light:
    16 metre x 450mm x 150mm and use similar, but a step down materials to the fantasy 100 footer.
    No spreaders but beside the three point main stays also have three point lower shrouds; plus runners attached to mast sides level with the main shrouds beak; runners do a very good job of keeping the rig steady. Also the thick section mast, purely from its shape, makes for a stiff and stable rig.
    Did I say don't listen to me -
    but if I had your cat, that is what I'd do.

    But I warned you.
     
  4. DennisRB
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    DennisRB Senior Member

    hehe. Its not for mine (she is only 43). Its already got a heavy overbuilt alloy rig. But I'm not going to change it as the one on it works. I am always adding to to my imaginary boat I might build some day. :p
     
  5. Marmoset
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    Marmoset Senior Member

    suppose an easy fairing bracket could be formed into trailing edge to allow an eye bolt for a spherical rod end boom mount would work. So let this < relax into this =


    Maybe rod end would allow a bit of under or over travel if sheet and boom angle are not perfectly lined up?


    Barry
     
  6. Gary Baigent
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    Gary Baigent Senior Member

    Perfect sailing day yesterday but had to go to a funeral; today not so good, onshore into the bay, but got the new main up although it took some time because the bolt rope is a very snug fit and snagged at the alloy track junctions (4 metre lengths) - so had to make a wet and dry sanding slide, attach halyard and a pull down rope and saw away until the junctions were smooth. Breeze freshened while completing this so reefed and set off. The sail is much larger than my bodgied up old one and the loads on the main sheet are considerably higher (to get the leech straight) - the result is, after hearing noises and watching the track and base flex upwards, I'll have to reinforce the track attachments to hull, glue a wood and carbon length below deck and carbon wrap it.
     

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  7. DennisRB
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    DennisRB Senior Member

    That looks the part now with the sail. I hope you get some good vids soon.

    Do you think the long pointy stern is doing much benefit in terms of drag reduction?
     
  8. Gary Baigent
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    Gary Baigent Senior Member

    Yes, Dennis, the rocker in the hull is almost non-existent (which is what I wanted) so the stern tends to drag a little because the hull is so narrow - so extended it to a point, main hull is now 8.5 metres and the stern slides through/over the surface with tiny evidence of the passing. Was an experiment (low rocker) but have changed my mind a little. However my broad sterned monohull, Cox's Bay Skimmer is completely flat (also what I wanted) and at slow speed, light wind, there is a carrying disturbance there (we shift forward to lift stern). However a bit more speed and it smooths out. Everything is a compromise, just depends which side you want to go.
     
  9. Barnian
    Joined: Jul 2011
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    Barnian Junior Member

    Nice looking sail Gary. Can you tell me who made it please. Ive almost completed a wingmast of the same sort of chord as yours and plan to put a soft sail on it of about the same aspect ratio as that one. I was planning to use slugs, what is your reason for using a boltrope? The mast may be almost competed but alas the boat is a year or two away as Ive just started one of the hulls.

    Ian
     
  10. Gary Baigent
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    Gary Baigent Senior Member

    Welcome to the crazies, Ian.
    North Sails. Josh Tucker handled the measuring (which is perfect) and offered suggestions with the design and build.
    Bolt ropes can be tricky, no doubt about that but I really dislike the slot gap of slugs - although they are certainly easier to hoist.
    But if you're going to the trouble of building a hyper efficient wing mast/soft sail - why have a draggy gap exactly where you want a smooth feeding airflow?
    Just imo of course.
     
  11. HydroNick
    Joined: Apr 2010
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    Location: British Columbia

    HydroNick Nick S

    Gary: That's an interesting comment about the gap behind the mast. I quizzed a sailmaker, who wanted to sell me a mast track, about that some years ago..."doesn't matter it's in the area of turbulence"; then about the track system that they sent me which when installed stuck out about 1.5 cm either side of the bolt rope slot (that's not the right term is it) in the mast.."doesn't matter". At that point I was beginning to disbelieve the responses. In the end, I returned the sailmaker's track system, re-installed a Harken track system that had come unattached with the boat...Farrier F-25c (and I guess despite all those questions to you about mast construction, I won't now need to build one). At least the Harken track is flush with the aft sides of the mast. So, despite my incredulity I have a gap; on the upside, the main is very easy to raise and easier yet to drop.

    One other point, any videos of Sid in action?

    Thanks

    Nick
     
  12. Gary Baigent
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    Gary Baigent Senior Member

    Hi Nick. On wing mast/soft sail connection area, that is where, on the leeward side, because of the wing foil shape to sail, there is increased air movement speed and low pressure. It is a basic, stick a gap in such an area and drag and turbulence will occur.
    Now, vortex generators create a turbulence that retains air flow attachment further toward the exit areas of the mast/sail foil shape, keeps flow attached (and also produces drag) - but the generators are not gaps but spikes - and they are on some aircraft but are useless things to have on a sail boat in terms of snagging gear and so on. But a slot on true full wing sail hard rig (like the C Class and the AC 72s and new AC62s) will never be situated in the forward area section of the wing foil (which is actually smooth and polished and very fair) where the air flow is bent and fast, but more towards the central and after sections, where the slots allow the slowing air flow to remain attached (by windward flowing air "rejuvenating" the leeward flow) for downwind sailing - and those slots are very, very carefully designed to do their job.
    Which is not like some crude gap or protrusions on your average and basic mast (which probably doesn't rotate enough as well). So yes, I disagree with your sailmaker mate.
    There are some short video sequences I GoPro-ed on board Sid earlier in this thread. Will promise more later - when I get the main sheeting base reinforced; am building the box-like frame right now.
     
  13. oldsailor7
    Joined: May 2008
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    oldsailor7 Senior Member

    Yes Gary, I quite agree.
    Lock had a pronounced curve on the trailing edge of his A class "Typhoon" wing mast, to match the natural curve in the sail. It also had a bolt rope track on the edge to seal the join with the sail as smoothly as possible.
    It must have been effective as Ian Turner won all three races, on both elapsed and corrected time, in the 1973 American A class championships in Florida.
    He was sailing one of the only two Typhoons ever built. The other one was destroyed in a car smash. I don't know how many of the standard Crowther A class cats were built.
    I'll see if I can get some pics up. :)
     
  14. HydroNick
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    Location: British Columbia

    HydroNick Nick S

    Thanks for the responses Gary and "oldsailor", they are interesting. So how do you get a boltrope system set-up so that it's easy to use and above all safe? When I got the boat, it was neither.

    Nick
     

  15. oldsailor7
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    oldsailor7 Senior Member

    Nick.
    I don't know what the trailing edge of your mast is like, but we just bought a length of boltrope track and screwed it to back edge of the mast.
    The sail was made with a matching bolt rope on the luff.
     
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