Gunboat G4 with UptiP Foils

Discussion in 'Multihulls' started by Doug Lord, May 12, 2014.

  1. Doug Lord
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    Doug Lord Flight Ready

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    I don't know: that capsize was not foiling related-it was a mistake by the skipper exacerbated by slow control of the main, in my opinion.
    For "cruising" the boat can be reconfigured with both foils partially down and set at zero degrees AOI and sailed like a "regular" cat-maybe with reefed rig. I don't think it will need a chase boat in that configuration any more than any other cat would. I think it is a "racer/cruiser" and can be completely reconfigured for either role.
    In a way I think it's good that this happened now so that the GB Team can fix the problems.
     
  2. pool
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    pool Junior Member

  3. cavalier mk2
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    cavalier mk2 Senior Member

    Not blaming the foils but any boat with this sort of power curve puts it into the easier to capsize bracket. I think there is a market for this sort of gung ho boat but that the possibilities of disaster should be dealt with. The Gougeon's did it the right way with their production racer cat. " Go ahead and push hard, if you capsize this is how the recovery system works." I think they'd get more buyers that way, these reality checks should be a wake up call for design and marketing to consider the possibilities in the planning stage.
     
  4. cavalier mk2
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    cavalier mk2 Senior Member

    Biggest mistake- not turning down.
     
  5. Doug Lord
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    Doug Lord Flight Ready

    G4 cruiser/racer on foils!

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    On the previous page as well....
     
  6. Doug Lord
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    Doug Lord Flight Ready

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    I agree.....
     
  7. Doug Lord
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    Doug Lord Flight Ready

    G4

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    I think the boat can easily be configured in "race mode" or "cruise mode", foiling or non-foiling....
     
  8. brian eiland
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    brian eiland Senior Member

    Which Sail causes Capsize ?

    I think I agree with you there,...it's just a sailor's most natural tendency to turn upwind in most of these circumstances.

    I would make note of the 'culprit sail' that most contributes to the final capsize.:?:;)
    https://vimeo.com/125378004

    (I don't think its that big reacher that's almost acting like a genoa at these relative wind speeds,....I think its that mainsail,...that's suppose to twist off to relieve that pressure at its head :rolleyes:)
     
  9. P Flados
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    P Flados Senior Member


    The "easier to capsize bracket" statement is probably very wrong spin. The early stretch of the video shows a boat smoking along in lumpy water with the bow slicing through waves. The foils seem to give a lot of protection from stuffing the nose.

    There are lessons to be learned.

    On this run, their speed had shifted the AWA very far forward. The main was sheeted hard down and traveler near mid boat. The boat is very fast this way, but not forgiving if not kept at a low angle of heel.

    Late in the capsize sequence, you can see how the loss of speed brought the wind around to keep pressure on the main.

    Easing off on the traveler earlier (say when the windward rudder came out of the water) would have kept the boat at full speed and not started the whole sequence of the capsize.

    The boat was being sailed like one of the fast "foiling beach cat" style of boats. However, constantly adjusting the main gets harder as you get bigger.

    A less aggressive trim on the main is probably all that would have been needed to keep the boat flatter and much safer while only being a tiny bit slower.

    The real lesson is probably just a repeat of the same learning curve that any full powered racing multi has to deal with.

    If you push real hard, you have to be ready to play out the sails as she heels too much. Then you have to be ready to dump the sails if you missed the chance to sheet out just enough.
     
  10. brian eiland
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    brian eiland Senior Member

    But who really wants to go just 'a tiny bit slower' when you are racing?
     
  11. cavalier mk2
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    cavalier mk2 Senior Member

    Hard to believe they didn't dump the mainsheet as well as the traveler.....I don't think the culprit is a sail, maybe belief in the advertising.

    I don't think that is spin P. More horsepower does increase risk factors. Foils may allow higher horsepower for equivalent risk but it was a in general statement. Obviously thinking they didn't have to sail carefully didn't work out too well.
     
  12. brian eiland
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    brian eiland Senior Member

    What force ultimately took them over?....from what source??
    I was basically making the point that it was the mainsail, NOT the headsail. I had some reasons for doing so that I may inject later.
     
  13. catsketcher
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    catsketcher Senior Member

    Thanks for the link Doug

    They sure pull that main in hard which is what you would have to do with a boat that pulls the apparent so far forward. The guys on Lending Club said that sheet tension was related to speed and it may be the same here.

    I think I can see the helmsman try to bear away but because he must be good he needs to maintain flow - you won't see a big tug but I think there is an attempt to bear off. Also it looks as though the rudder lost bite just as they head up - I see the boat slew slightly to leeward and then head up even with rudder over. Foiling would make it easier to lose flow over the rudders as they get smaller and more aerated. It always seemed to me that reattachent of flow could take a long time - sometimes 15 seconds after loss so ot could be very tricky to sail this boat. Also there is only one rudder in the water so she sure is loading up the lee rudder heavily.

    As for the main, it would be good if they had a dump button on a second part of the mainsheet - hydraulic one end - panic button on rope to clutch or similar other end. Even easing the main will do little as the apparent comes way aft quckly as she slows down. The main was more oversheeted at the end of the capsize because of the apparent moving aft as the boat slowed - you have to dump the whole thing to have a chance - typical skiff or cat problem in death zone sailing. "Blow it! Dump it!" I have heard that a fair bit on race courses not "Ease please" in this situation.

    That being said you can't call this a cruising boat. It is very interesting but you won't find anyone taking it out and pushing hard with their family on board. A cruising boat can go fast but it needs to do so with ease and safety. In winds of over 15 knots I always throttle back as the accelerations get too high, things happen too fast, I could break something but most importantly - my wife will not like it and who cares if we get there a bit later if we are all happy, the washing up gets done enroute and the autopilot steers instead of me.

    Bay racer, Cuddy cabin cat, Day cruiser, Sleep on foiler, party foiler but not cruiser.

    cheers

    Phil
     
  14. ch3oh
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    ch3oh Junior Member

    Is there a need to push it to the limit while cruising? When depowered to fountaine pajot speeds there's no apparent reason why it should be less safe than one. Its wider, cog is lower and overall construction is stronger, bridgedeck clearance has no bulbs that suddenly add volume, added RM of negative aoa foils..
     

  15. P Flados
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    P Flados Senior Member

    The old phrase that pops into my mind is: To finish first, first you have to finish.
     
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