buccaneer 40 mods

Discussion in 'Multihulls' started by sailorman282, Jan 18, 2016.

  1. sailorman282
    Joined: Jan 2016
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    sailorman282 Junior Member

    hi I am new to this site am a professional boatbuilder and am completely rebuilding a bucc 40 trimaran,would like to install fixed foils in floats any ideas of some that have worked?thinking of putting a small winglet on the inside of floats above waterline and at an angle of attack of say 2 deg ,winglet approx. 400mm l x 400 mmw and installed at an angle so when the boat is heeled they become level with w/l across with naca foil and angle of attack to give lift.winglet at front beam connection area.any thoughts?
     
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  2. bruceb
    Joined: Nov 2008
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    bruceb Senior Member

    float foils

    Sailor, I am strictly an amateur so consider the source, but I have experimented with float foils on my Buc-24. The hull forms are about the same, and mine seemed to work very well. I put trunks in my floats just behind the forward cross beam and found that a much smaller foil gave the same lift as my high aspect main dagger board, and the helm did not change. Mine were also set at about 2 degrees of attack. I do question if the windward hull will lift enough in lighter conditions to get the foil clear of the water? Mine of course were retractable and needed to be lifted.
    B
     
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  3. sailorman282
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    sailorman282 Junior Member

    hydrofoils

    Thanks for the reply bruceb I should have included a drawing and said hydrofoils, basically I meant fixing half a t foil to the inside of hull above WL around 200mm so when float is depressed it creates more buoyancy as you probably know the bucc 40 floats are meant to be submersible and therein lies the problem as I have rebuilt the cabin and added a large cockpit where aft cabin is I don't want make longer floats as well...
     
  4. bruceb
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    bruceb Senior Member

    lift

    I think I understand what yours would look like. If you are just wanting lift, it doesn't take very much area. I also put mine in to create some lift, I actually got more than I expected and had to reduce the size quite a lot. These photos are of the first set, I had more than enough lift with them half down. They make the boat feel "larger" and at any speed very hard to push the float down more than half way. My are exited more vertical and below the waterline than what you plan. These were my first set and were 280mm x 1000mm below the hull- way too large for my boat. ;)
    Good luck :)
    B
     

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  5. sailorman282
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    sailorman282 Junior Member

    hydrofoils

    thanks for the pics bruceb they look like they would work well ,I was planning on using a similar foil shape but fixed permanently and at a much greater angle about 45 deg so when the boat is heeled they are just lifting up the hull they wont be any deeper than the hull bottom and wedge shaped so as not to snag anything in the water .location will be right on the forward beam bulkhead for strength and I think I should put them in very strong cases perhaps so the cases only are permanent and stick out say 150mm and fin could be changed in case the size too small /too big?If yours work well I think there shouldn,t be a problem except they will need to be strongly attached foam core removed in area etc.cheers Ross
     
  6. Marmoset
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    Marmoset Senior Member

    would love to see pics of boat and work done!


    Barry
     
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  7. sailorman282
    Joined: Jan 2016
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    sailorman282 Junior Member

    bucc 40 modifications

    heres some pics of the work done ,she was a real mess and had an ugly aft cabin that had to go also a real heavy fitout that has now been removed ,new cabin top makes for a roomy brighter and also lighter weight cabin ,foam sandwich top and cockpit floor
     

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  8. sailorman282
    Joined: Jan 2016
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    sailorman282 Junior Member

    bucc 40 mods

    some other pics with new stern and steps to cockpit,the original cockpit on this design was tiny and I found it difficult to work in on wings with rope tails everywhere and nowhere to sit
     

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  9. Corley
    Joined: Oct 2009
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    Corley epoxy coated

    The rebuild looks great, Nice to see the old girl getting some love. I've seen photos of the boat looking pretty ratty for years.
     
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  10. bruceb
    Joined: Nov 2008
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    bruceb Senior Member

    Keep them alive

    Sailor, that is going to be a nice looking Buc. I like the big cockpit- Crowther designed some nice tris, but his cockpits and foils were undersized :mad: It looks like you are addressing both issues.
    I just finished rebuilding a foam cored Buc-33, I understand the size of your 40 project. Of course, I am also jealous :)
    B
     

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  11. warwick
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    warwick Senior Member

    [​IMG]

    sailor man would this be your boat around march last year? near mission bay
     
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  12. Gary Baigent
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    Gary Baigent Senior Member

    Sailorman, Seeing you've stripped some heavy rubbish from your B40 (and hopefully not added any more) then you'll probably find that your lighter boat with its larger floats than the Kraken 40, will not bury the floats under higher wind loads anyway. However foils will definitely stiffen your platform up further. I have fixed foils on Sid and they are set no deeper than the bottom of the main hull when level, see photographs. Or alternatively you could mount liftable foils like on this lengthened B24 - which has no main hull dagger, relies on the float foils for lift and also anti-leeway when beating.
    Setting your proposed foils above waterline I think will tend to allow aeration and erratic platform balance, wobbling - because you'll find the lift is impressive and you leeward float will ride considerably higher than before and then the foils will cavitate/aerate and the lee float will temporarily drop lower.
     

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  13. sailorman282
    Joined: Jan 2016
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    sailorman282 Junior Member

    yes Warwick that would be the boat getting prepared for the film,unfortunately all the paint was acrylic house paint and it has taken weeks of paint stripping to get it off!Thanks for the pics Gary ,I reckon I have removed over 500 kg from the yacht and am trying to replace it all as light as possible the boat has been overbuilt as well so just can,t get rid of enough xtra weight but plan on taking her ocean cruising so not being a super light weight may not be too much of a problem.The foils I wanted to put on are mainly to try and prevent the float deck going under so may not have to be too large ,not sure on how much area would be required for that?
     
  14. bruceb
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    bruceb Senior Member

    size

    Sailor, I realize these are not the same, but at least a guideline. My foils, both the first set and the ones that are still more than enough for my 24 are a N2408 "flat" bottom shape. They provide both lateral and vertical lift and work well. My 24 is about 1100 kg loaded and the foils are about 225 x 800 mm. I used the 2408's as they work fairly well at lower aspect ratios and resist stalling at low speeds. A thicker section at 10% to 12% might even be better, but maybe a little more drag at higher speeds. These foils are operating at or near the surface and don't respond as well to the usual lift/drag models.
    The 2408 have 2% 0 lift angle, so set at 2 degrees, they are quite powerful.
    B
     

  15. sailorman282
    Joined: Jan 2016
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    sailorman282 Junior Member

    thanks Bruce that sounds like a good place to start,mine will have to be a fairly low aspect and tapered also if they are fixed ,I think they will also need wing tips to reduce cavitation ,so how does 400mm base 300mm tip and extending out from the hull say 450mm and 10% thick section and removable like a surfboard fin box[but much stronger] and set off the hull at 45 deg to horizontal,growth on them will be a problem perhaps .
     
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