Capsize Prevention Devices

Discussion in 'Multihulls' started by brian eiland, Jan 16, 2012.

  1. brian eiland
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    brian eiland Senior Member

    Capsize (in slow motion)

    Interesting video of a large tri capsizing (almost appears to be slow motion, but its not)

    https://www.youtube.com/watch?v=YganM4xVTac
    I was looking at this video and the time it took to go over,...and wondering why there was no release of the sheet lines. Don't these vessels have the UpSideUp release systems onboard?

    Then I did notice that the jib appears to have been release, but not the main,...that took her on over.
     
  2. brian eiland
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    brian eiland Senior Member

    Hydraulic Release Systems

    A fellow from France has left this comment on Sailing Anarchy
    Does anyone have more photos and details of these 'hydraulic release systems' ?
     
  3. brian eiland
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    brian eiland Senior Member

    An interesting posting from THIS PAGE
    http://forums.sailinganarchy.com/index.php?showtopic=165151

    ...another observation on that page
     
  4. brian eiland
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    brian eiland Senior Member

    ...from that Sailing Anarchy page again
    http://forums.sailinganarchy.com/index.php?showtopic=165151


    That reference to the Smyth Team system just brought back my old memory cells again. I had forgotten it :eek: :eek:
     
  5. brian eiland
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    brian eiland Senior Member

  6. brian eiland
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    brian eiland Senior Member

  7. Skip JayR
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    Skip JayR Tri Enthusiast

  8. brian eiland
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    brian eiland Senior Member

    ...from Sailing Anarchy

    Just to clear up the misinformation:

    1. the rig cants 9 degrees.

    2. with the rig canted and the mainsheet tight, the traveller will not drop even 1 inch to leeward.

    3. the release mechanism for the main looks slow, but it is plenty fast if it is the first thing that is used.

    4. the Virbac capsize was caused by trying to drop a traveller which would not move, rather than the mainsheet, and the helmsman did not manage to blow the sheet release as the boat was already too high up and he was trying to hang on and drive at the same time.

    5. it is not the size of the hoses which causes the system to be slow, but the ID of the valves. only when the valve is at maximum diameter does it make sense to go to larger hoses.

    6. hydraulic power comes from a pump which is attached to the coffeegrinders

    moving the ram one foot pulls in 6" of mainsheet as it is a 2:1 system. before anyone tries to count the blocks, it looks to be a 4:1 simply because the load is split between two 2:! systems in order to use smaller non custom blocks for the 11 ton load.

    7. no one is dropping the rig to leeward, as touched on above it is the roach of the main which needs to be depowered.

    8. you can be sure that NO ONE will fit an explosive device to cut the clew strap. imagine the damage that the boom would do to the roof, not to mention that the boom would probably break on the traveller track as it recoiled.

    9. the upside up system which uses a computer to monitor heel and pitch and then blows the lines out of the camcleats at preset angles is functional and the choice of all these boats.
     
  9. Skip JayR
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    Skip JayR Tri Enthusiast

    hydraulic pumps, explosive devices.... all sounds too complicated.

    I think a good sensor and processor, and opening the main sail and traveller sheets by time. - Thats it. It must be something very simple, isnt ? A boat is not a car with an airbag. But with the airbag we see, that there are sensors which can react quickly enough.
     
  10. Jim Caldwell
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    Jim Caldwell Senior Member

    I would put them on main sheet and job sheet first, as they blow off the twist would depower the tops first for more righting moment faster.
     
  11. philSweet
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    philSweet Senior Member

    That might work if you are sailing at 50% of your capsize RM and want to handle a doubling of the force. But it won't be good enough if the gust brings a ten fold, or 100 fold increase in load. I've seen what a microburst can do. Trees don't get knocked over, they shear off at ground level and collect in a mile long impenetrable wall of wood 150 feet from the lakeshore, all still standing. I'm talking 150' Douglas firs with 3' diameter trunks.

    In a separate incident, I had the 20' deck-stepped mast on my dink buckle in three places before the boat capsized. The gust was in the 150-200 mph range and the downdraft was about 50' in diameter, leaving a spherical, 5' deep depression in the Florida bay as it wandered around, eventually collecting me.

    I've also been hit by a tiny waterspout. My parrot was in her cage at the front of the cockpit and the cage nearly got thrown overboard. The cage looked like it had been hit by a baseball bat and the poor bird looked like it had been sucked though a vacuum's hose. The sails cracked like coachwhips. I felt nothing at the helm. Not even a whiffle. The parrot's cage had ground corncob litter. The spout sucked it all up and I got a brief look at it. It appeared to pass through the mainsail. Perhaps it got concentrated trying to squeeze under the boom. Fortunately, it chose not to go down the companionway and wreak havoc below. Maybe this is where ghost stories come from.

    The point being, you need to decide what sort of load you are trying to mitigate - 50% increase? 200%? 1000%? 5,000%?

    I've sat on my boat in the Florida bay listening to hundreds of boaters screaming on ch16 that they have 100Mph winds, and NOAA cheerfully broadcasting it's chamber-of-commerce forecast "winds 15 to 20, maybe be higher around thunderstorms" A superyacht delivery captain reported that his wind meter was pegged at 85 knots for fifteen minutes and he had gusts to about 115 knots. Ever seen a roll cloud? Those things have to show up on radar. This squall hit like a switch. 15 knots to 100 knots in less time than it took to swing on the anchor. And I found a dead, frozen solid hammerhead shark on deck when it was over.

    Stock photo, not mine.

    [​IMG]
     
  12. Jim Caldwell
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    Jim Caldwell Senior Member

    Nothing will save you in a really bad Microburst!
    Search for Microburst deaths.

    It works very well racing B cats when you are paying attention, we tried to never let the windward hull get more than 10 degrees but the key is the rate it lifts.
     
  13. hump101
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    hump101 Senior Member

    I've not experienced anything like PhilSweets microbursts, but we had the wind go from F0 to F9 in under a minute in the Adriatic once. Fortunately we were motoring (no wind) but we were instantly gunnel under (monohull keel boat) with bare poles. My F40 would have been capsized in the same conditions, and no sail release capsize prevention device would have helped, other than one that can dump the mast somehow, and I haven't thought of a safe way of doing that.
     
  14. brian eiland
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    brian eiland Senior Member


  15. hump101
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    hump101 Senior Member

    I'm also not saying that a sheet release system is not of value - it clearly is and is essential on my boat with few crew. I'm in the process of working out the best system to use, but I'm also conscious of the fact that it won't cover all eventualities. I'm looking at combining a sheet release system with the autopilot, because when the boat is off the wind it is safer to turn down than release sheets, in fact releasing sheets is worse when combined with turning downwind. Hence the system needs to know the wind direction, wave direction, boat motion (roll, pitch, yaw) and sheet positions, and make an intelligent choice of what to do.
     
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