6.5 to 7.5 metre performance/cruise multihulls

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

  1. Gary Baigent
    Joined: Jul 2005
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    Gary Baigent Senior Member

    Testing Frog, some good, some not so good but getting the thing sorted. Had to increase foil length, not enough lift before. And here's the new Bill Barry double luff main.
     

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  2. redreuben
    Joined: Jan 2009
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    Location: Beaconsfield Western Australia

    redreuben redreuben

    Gary how’s the double luff main looking ? this idea really interests me
     
  3. Gary Baigent
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    Gary Baigent Senior Member

    Looks and sets fine. I don't attach the batten ends and the two main leeches are only connected at the boom/clew position. Thought this might be dangerous, meaning that when gybing with the wind getting into the sail before swinging across, there might be problems but so far, no problems. The leeches have to move because the windward sail sets shorter on the boom (if you can understand what I mean). The D mast rotation seems to be much the same (actually a little less) as normal teardrop cross section wing, meaning it has to rotate 45 degrees when sailing to windward. I can't get any decent photographs when sailing because the boat is so cramped and small; need someone in a powerboat alongside.
     

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  4. Gary Baigent
    Joined: Jul 2005
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    Gary Baigent Senior Member

    Extended stern so Frog is now 7 metres length, also had to add diagonals from shroud bases to main hull after damaging the cantilever beam/hull section at the hard point, plus extending the lower float foils and adding a brace to stop flexing. The upper foil never, well, very rarely touches water. Slowly figuring the Frog out; taken a while though.
     

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  5. redreuben
    Joined: Jan 2009
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    Location: Beaconsfield Western Australia

    redreuben redreuben

    Living testimony to; "If it breaks it's too light if it doesn't break it's too heavy" :D
     
  6. trip the light fandango
    Joined: Apr 2018
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    Location: Rhyll Phillip Island Victoria Australia

    trip the light fandango Senior Member

    The treatment you've done to your stern , the scoop, is almost identical to what I am considering doing to my Trem, , except your finish looks perfectly faired, and the paint professional [one day], and i'll move the rudder back so I can beach and drag. Have you noticed a difference in performance that can be attributed to the dieters sugar scoop? It looks like it belongs, is it functional, does it really add a little speed, buoyancy and better sea keeping?
     
  7. Gary Baigent
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    Gary Baigent Senior Member

    Added it because I have maybe an unhealthy fixation anti- dragging sterns - and the extra half metre length and slightly lifted exit area has cleaned up the wake. If there is no turbulence there in light airs then have convinced myself the boat is faster. Maybe delusional. Here's the light airs wake of my late lamented Sid (smashed in storm while moored). There is very little rocker in my boat designs, hence the stern extensions.
     

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  8. trip the light fandango
    Joined: Apr 2018
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    Location: Rhyll Phillip Island Victoria Australia

    trip the light fandango Senior Member

    Wow that's an impressive lack of wake .
    No lab test and pages of complex mathematical equations..which I wouldn't comprehend,. drats .
    That is part of my justification too, beacause before I added an extra skin to the bottom of the hull,for buoyancy, extra freeboard ,safety, the trem had very little disturbance in light airs.
    So to see the slight extra turbulence is nagging at me. If extra length adds hull speed, all things being equal[ha] you should have increased the speed by about one 12th..? , a metre being one 6th roughly.as the frog was 6.5... I have to confess no real idea how the wetted surface, drag, length , beam, displacement formula actually works, so I plan to mess with it..and I want a spot for a small LPG bottle.
    I'm tempted to reach for nearly 1metre but it will be clearer what looks ok and works when I'm actually doing it, maybe , ha . I can improve the entry easily by making it pointier, the stern is about 150mm below the surface and a similar width. Anyway your Frog is fascinating and inspiring , thanks for the reply.
     
  9. bjn
    Joined: Jul 2014
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    Location: Stockholm

    bjn Senior Member

    I remember seeing this cool trifoiler on youtube a few years ago. Does anyone have any info/news about it?

    Glen Robert's hydrofoil trimaran
     
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  10. Gary Baigent
    Joined: Jul 2005
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    Location: auckland nz

    Gary Baigent Senior Member

    Very interesting boat. Ahead of the times. Although the Lord of make-believe will dispute this? Have they sailed it with a rig?
     

  11. Doug Lord
    Joined: May 2009
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    Location: Melbourne, Florida

    Doug Lord Flight Ready

    As of the test date this trimaran used manually controlled main foil flaps-moved with pedals. Differential lift for RM would be kind of tricky...... It would be a piece of cake to add dual, independent wands for sailing which would automatically add RM as required.
    ------
    Gary, how about a picture or video of one of your gorgeous boats foiling?

    I may be wrong but I think Dr. Sams 40' Skat was sailing in about 2005?

    Skat bradfield 40.jpg
     
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