self righting stability

Discussion in 'Stability' started by valvebounce, Jul 1, 2012.

  1. valvebounce
    Joined: Dec 2010
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    valvebounce Senior Member

    That's some design plan PAR.I had no idea the mast could submerge by 5%,and the boat would still self right.Would there be any crew left topside,or would they all be below battened down in watertight cabins?I suppose all hatches would have to be sealed to prevent flooding.At what point would you make a decision to use this procedure?Would you have lost steerage capabilities and sit it out trusting to the boats self righting capabilities?Would you retract all sails or still need to make way?
    If my old Dad was still around he would have been fascinated,he was a chief petty officer in the royal navy during the war,then a design engineer/draughtsman for A.v.roes,british aerospace,english electric,and dunlop.He was even offered a job on the moonshot program in Hollywood.
     
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    That rings a bell Valve, does A.V.Roe = Avro ?
     
  3. valvebounce
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    valvebounce Senior Member

    Hi mr E,
    it certainly does,as in Avro lancaster, Vulcan etc.My Dad started his career there.
    I seem to remember him saying he helped in the design cone on the Bluestreak rocket.
    We worked together at General motors in Salmon st Melbourne for a while,I was an experimental toolmaker apprentice,white overalls etc etc.Haha. Coming back to smokey old Britain saw an end to that.I ended up as a Bricklayer,swapped thou's for 1/16"s.An easy transition apart from the weather.
     
  4. PAR
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    PAR Yacht Designer/Builder

    On that particular boat Valve, the rudder is effectively useless at about 70 degrees of heel and completely out of the water shortly thereafter.

    Of course these aren't angles you try to operate the vessel at. You try to keep the boat "engaged" and making way, but gusts and/or waves can knock you over, past practical angles that you can work with. Naturally, you want tight hatches and secured crew members. MOB drills in sea state conditions that are likely to cause these heeling angles, are usually fruitless efforts to just find a body.

    The skipper can usually tell when it's time to "batten down" and insist on safety harnesses. Things become self evident when conditions deteriorate enough to warrant getting scared.

    Again, the boat I mentioned can be rolled over, so it's mast is pointing nearly straight down and she'll still roll back upright. If this does occur, she'll likely come up with damage, probably without her rig and no one inside the boat is going to be in a good mood, but she'll be upright and likely able to "carry on" under power or jury rig. The ability to get home is a fairly important thing, when farther from shore then you can swim back to. Even if you have to limp.
     
  5. valvebounce
    Joined: Dec 2010
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    valvebounce Senior Member

    Think I'll go by train.Sounds exciting stuff,bet you have to be fit.
    I crept round a motocross track on a 250cr honda a few years ago,It exhausted me completely,just holding onto the bars was a job in itself.On a motocross bike stability is maintained by power,unlike a road bike that can powerslide on corners,you power up,and it digs in.
     
  6. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    The most physically demanding sport is motocross. I use to ride a lot as a kid, but wouldn't even attempt it with my hips and ankles now.
     
  7. valvebounce
    Joined: Dec 2010
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    valvebounce Senior Member

    I'm off on a camping holiday in a fortnight in Anglesea North wales.I am taking a 9ft inflatable with a detachable transom,I am using a 40 plus seagull engine on it.
    It's been a juggle to set it at the right height on the transom,too deep and the back pressure slows the engine,too high it gets nowhere.They are designed for displacement hulls really.This one will push a 16ft boat no problems.The water is cold here,so what happens is when the inflatable has been in the water 15mins or so,it reduces the pressure in the tubes and causes the boat to ride deeper,especially at the engine end.
    So after 15mins or so I re inflate,and it solves the problem.
    Hoping to do a bit of trolling for mackeral and sea bass for the barby.We have 3ft rods designed for kayak fishing.Should be a laugh if nothing else.
     
  8. philSweet
    Joined: May 2008
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    philSweet Senior Member

    Um, reading your post #11, I may have been a bit confused. The material specs I mentioned were for the foredeck and cuddy structure, not the cockpit. PAR gave you those.

    PS. My dad was a flight instructor on Avro Ansons. He wanted to go up in one on his 90th b'day, but I couldn't find one.
     

  9. valvebounce
    Joined: Dec 2010
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    valvebounce Senior Member

    Hi Phil,all the info is digested and appreciated,this boat is a first time project for me,being able to converse on here is invaluable.
    Hope your Dad had a good birthday,please pass on my best regards.
    I went to the 50th anniversary of the Dambusters,they flew a Lancaster, a spitfire and a hurricane,wingtip to wingtip, over the dam near sheffield where they practised during the war.The turnout of people was huge,some of the spectators had to walk 3 miles from where they were parked.
    The Avro Vulcan from the 50's was used as a ferry service in the late Falklands conflict.
     
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