6.5 to 7.5 metre performance/cruise multihulls

Discussion in 'Multihulls' started by Gary Baigent, Feb 27, 2015.

  1. santacruz58
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    santacruz58 Senior Member

    Hi Gary. How is frog coming? Did you get a sail? Hope the weather is better in Auckland. I am still waiting for summer down here in Lower Hutt.
    nelson
     
  2. Gary Baigent
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    Gary Baigent Senior Member

    Frog has been stationary for some time because I've been fooling around with the Cox's Bay Skimmer. Also lowered Sid's mast a couple of days before the 45- 50 knots directly onshore, no protection wind blasts hit last weekend. Pleased I did because mast would have come down for sure.
    Also had a somewhat unwelcome big Piver visitor (broken mooring chain) into the bay; a few more metres (lucky that we were having low 2.8 metre tides) and it would have skittled Frog and a number of boats, not to mention its own destruction against sea wall. Second shot shows the drag trail of the float fins on the papa rock.
     

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  3. Andy
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    Andy Senior Member

    Any more on this Gary? Been a while since the last update - hope its going well
     
  4. Gary Baigent
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    Gary Baigent Senior Member

    Have been very slack regarding finishing the Frog - which is floating on mooring but now has a decent crop of weed growth on bottom; the parore enjoy feeding on it. Worked on the rebuild of Cox's Skimmer and then built a new mast for Groucho which took some time. Weather here has been its usual winter savageness.
     

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  5. cavalier mk2
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    cavalier mk2 Senior Member

    Hey Gary, been wondering about you now that I realize summer is here. Our off season was soggy for the record books, What is this year like for you? I'm taking notes because I think there may be a correlation and want to brace for the worst. Beautiful here, had to go to the slow cure catalyst some time ago. I've decided to work on things now because I'll have the 8 months of rain to sail in.
     
  6. Gary Baigent
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    Gary Baigent Senior Member

    Hi Cav, Dante's Inferno in wetness here at moment although it hasn't been cold - because we've had winds from the north east, coming in from the salubrious Pacific far away over distant horizon, where dancing wahines and swaying palms exist. But not here now that wind has swung west with lightning and thunder.
    Here's another shot of Frog. Had to extend the tiny floats; not enough buoyancy - but need to increase volume even more - will do it later. At the moment I've lashed a tubular fender each side below the low foils. Otherwise the platform nearly tips over in strong winds. The idea (how brilliant?) was that once moving the foils would create lift - doesn't work so well when stationary though.
    Last shot is an old 1970s one of Noel Fuller's tiny 14 foot foiler Sabrina in which he sailed from here to Bay of Islands, 130 odd sea miles.
     

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  7. cavalier mk2
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    cavalier mk2 Senior Member

    Beauty Gary, Lift...it's what the wing decks are for. Looks good, keep it up. I'll brace for the rain again.
     
  8. cavalier mk2
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    cavalier mk2 Senior Member

    Ever think about about a ballast (hate that word) bulb on the dagger end? When they get that close to the fine line might as well borrow from both. By next year I'll have to sail for the vahines, the locals can't use a sander....
     
  9. Gary Baigent
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    Gary Baigent Senior Member

    Lead ballast you say on dagger? What horrors?
    No and seriously I think when I get my a. into g. will build slightly larger and set lower floats - so the upper foil exits at halfway depth mark of the float. So if overpowered the foil will solidify the heeling position. That's the theory anyway.
     
  10. cavalier mk2
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    cavalier mk2 Senior Member

    Sounds interesting, and I can't disagree. When looking at top down- wings/amas or bottom up- ballast it does seem a balance is required. My mono ldb always made me wonder if it would do even better with ama foils upwind as past the beam reach it would fly. It actually caught a few tris.
     
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  11. Gary Baigent
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    Gary Baigent Senior Member

    Chopped off the old and fitted new and enlarged (relatively speaking of course) mini floats to Frog; they are set lower to WL too. Bit of paint and maybe I can bodgey up a sail (Flash Harry's old main) to fit one of the D mast tracks; will give a rough indication how the water reptile will sail. Giving thought to how the new double luff main will be designed.
     

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  12. patzefran
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    patzefran patzefran

    Gary, I am just curious : did you provided any mean to tune the foils AoA (e.g. rotating the whole wing beam), or are they fixed ?
    If not, I assume you aim to control pitch attitude using the rear rudder foil ?
     
  13. Gary Baigent
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    Gary Baigent Senior Member

    I could rotate the main beam to alter foil attack angles, pack leading or trailing section of the central box. But when sailing would be fixed. But then again, you could rig a mechanism to move the beam when underway too. At the moment the lower and main foils are at 3 degrees and the uppers double that. The upper foils are meant to be the safety oh sheet fail/safe parts of the Frog. However I've found with my other foilers that once moving the main foils lock into the water. If Frog works okay I can later add more refinements to foil angle control. The rudder T is at zero AoA. But Frog is a small boat and you could shift weight forward or aft to alter that as well.
     

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  14. patzefran
    Joined: Feb 2011
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    patzefran patzefran

    Thanks, Gary
    I am experimenting curved daggerboards (Naca 2412 from a Bim Zero A cat) on the outriggers of my Strike 15 Tri. I used different AoA on either side.
    3° on starboard side, more on port side ( around 5°). Lower AoA works fine, but not so good the higher (lot of ventilation). My best velocity is consistently 14.8 kt beam reaching with starboard outrigger on lee.
    The gain with the foil is around 1 kt.
     

  15. ALL AT SEA
    Joined: Nov 2013
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    ALL AT SEA Junior Member

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