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bferry View Drop Down
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Posts: 190 		Post Options Post Options   Quote bferry Quote  Post ReplyReply Direct Link To This Post Topic: V Twin
    Posted: 25 Apr 12 at 12:33pm
How about trying out 2 centre boards, one on each hull side.  Would this help with the righting moment?  Or possibly a longer central board which would create more leverage?
Bernard
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blaze720 View Drop Down
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Posts: 1635 		Post Options Post Options   Quote blaze720 Quote  Post ReplyReply Direct Link To This Post Posted: 25 Apr 12 at 1:11pm
Greame

We all never stop learning ... unless / until we choose not to learn.  There is nothing like trying things for yourself and learning directly rather than accepting second-hand learning. 

There are a lot of cliches that can be used here including 'What does not kill us generally does make us stronger' so keep at it as long as its still teaching you .... despite all the ribbing you will continue get  (but)  if it ever gets to the 'flogging of dead horse' stage .. seriously ...  bite the bullet and move on.   You often need THREE attempts to get to where you hoped to get in one hop.  

Everything learned looks so bloody obvious to everyone else (who tend not to try things themselves) when you try stuff ... and to you of course as well  but only after you've tried something for real !! 

Mike L.
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Mark Antony View Drop Down
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Posts: 34 		Post Options Post Options   Quote Mark Antony Quote  Post ReplyReply Direct Link To This Post Posted: 25 Apr 12 at 2:26pm
Originally posted by simonrh

Didn't the catapult have shrouds that allowed you to leave the rig partially in the water when righting?



That's a clever idea. A ratchet or some sort at the shroud fixing point on the hull to play out 2 0r 3 metres of shroud. This would allow the hull to be got to 45 degrees angle before the drag of the sail plan is encountered. At that leverage point, Grahame's weight ought to be sufficent to do the rest. Even from inverted, the lessening of the drag must be of some assistance in getting the hull back from inverted.
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ASok View Drop Down
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Posts: 739 		Post Options Post Options   Quote ASok Quote  Post ReplyReply Direct Link To This Post Posted: 25 Apr 12 at 2:51pm
Isn't that how the firebird cat a few pages ago worked?
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themeaningoflife View Drop Down
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Posts: 212 		Post Options Post Options   Quote themeaningoflife Quote  Post ReplyReply Direct Link To This Post Posted: 25 Apr 12 at 2:52pm
Exactly what I was going to say: see here  http://www.catapultcats.com/sailtech.capsize.html
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Atrocity View Drop Down
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Posts: 42 		Post Options Post Options   Quote Atrocity Quote  Post ReplyReply Direct Link To This Post Posted: 25 Apr 12 at 3:11pm

There has been much discussion over the past few days regarding getting the thing upright after a capsize, but nothing said about how it was going prior to the incident.  Looking at the photos there was no shortage of wind (looks like a full force 4), and a good range of boats from which to measure against (RS400, 470, Contender, Merlin Rocket, RS Vision and Lasers).  I would be really interested in how the boat was performing relative to the competition. 

The key question is, were you swapping tacks with the RS400 (in which case the project has legs and a solution to the capsize issue is worth pursuing) or swapping tacks with the Vision (in which case it may be time to cut your losses and buy a Vareo, because if it didn't go in that wind then the time and effort making it easily rightable will be to no avail).

Atrocity
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RS400atC View Drop Down
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Posts: 3011 		Post Options Post Options   Quote RS400atC Quote  Post ReplyReply Direct Link To This Post Posted: 25 Apr 12 at 3:28pm
Originally posted by Atrocity


There has been much discussion over the past few days regarding getting the thing upright after a capsize, but nothing said about how it was going prior to the incident.  Looking at the photos there was no shortage of wind (looks like a full force 4), and a good range of boats from which to measure against (RS400, 470, Contender, Merlin Rocket, RS Vision and Lasers).  I would be really interested in how the boat was performing relative to the competition. 

The key question is, were you swapping tacks with the RS400 (in which case the project has legs and a solution to the capsize issue is worth pursuing) or swapping tacks with the Vision (in which case it may be time to cut your losses and buy a Vareo, because if it didn't go in that wind then the time and effort making it easily rightable will be to no avail).

Atrocity

Depends who's sailing the Vision! Those things go all right with a good helm and a crew on the wire.
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sargesail View Drop Down
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Posts: 1459 		Post Options Post Options   Quote sargesail Quote  Post ReplyReply Direct Link To This Post Posted: 25 Apr 12 at 7:29pm
The Catapult was also what I had in mind when I mentioned Teignmouth Electric - the latter was meant to have an auto release on rig/sheets to prevent capsize.

Now if you were to rig lots of Merlin style rig adjustment, but with the option to adjust on a single line, on a single shroud then you have a foolproof method of righting/preventing turtle.  Doesn't help when it's gone all the way tho.

Matt
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zippyRN View Drop Down
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Posts: 437 		Post Options Post Options   Quote zippyRN Quote  Post ReplyReply Direct Link To This Post Posted: 25 Apr 12 at 7:33pm
Originally posted by G.R.F.

A lot to sift through here, some good ideas and excellent hindsite, a skill I'm becoming increasingly expert at.

The boat has bulkheads, I guess it wouldn't be difficult to ensure the side tanks flooded, but then they would both have to flood, then er wouldn't that be called 'sinking?'.

it's only as daft as the  floor 'tank' in some ribs  that fills as you slow or stop to sit the boat 'down' in the water 

does the V twin have 'excess' buoyancy  and if so how much ?  or is  it a case of moving where the buoyancy is 

the design does appear to have the inherent inverted stability  that you'd expect from a cat ... 

I also suspect you can't 'unstick'  by  sinking an aft corner , as seems to help some more conventional dinghies 

The reason all this is taking the time it is, is because I wouldn't dream of taking it out without rescue cover and had already briefed the boys in the boat that it would likely be difficult to right and if I did go over, only sort me out after any or everyone else is sorted.
<snip>
So some conclusions that I now draw from all this.

1) Dinghys are made to go over deliberately easily so they can be easily righted, I wish someone had told me that.


thus is the inherent nature of an unballasted sailing boat with a fixed to it rig 

2) If they do go over it is better that they sink, at least partially, (now I understand the logic behind the Alto, not that it goes over often but if it does it comes up full of water which always irritated me in the past)

while it;s  easy to think you can never have 'too much' buoyancy ...  it;s relatively easy to do this in a dinghy - while some older designs  were marginal at best ( especially  as originally built with all bag  buoyancy e.g Ent ) 

3)Windsurfing rigs that just fall over flat are so much better than these stupid things with wires holding them up, maybe I should just rethink how the mast is held up and fix it so it falls over rather than the whole thing going over, it would also solve the getting away from me problem if I did happen to fall in.

i think the problem there is the case of getting the mast  back to upright and central once you've 'banged out'  through whatever method 
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tickler View Drop Down
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Posts: 895 		Post Options Post Options   Quote tickler Quote  Post ReplyReply Direct Link To This Post Posted: 25 Apr 12 at 7:49pm
I still go with my inflatable bag and hull mounted gas tank. that is a simple and presumably cheap modification which would provide mast head floatation without tying an airbed to it. Mind you sailing in with a deflated giant condom hanging in the shrouds would be a bit like the walk, or rather sail of shame.....
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