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tgruitt View Drop Down
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    Posted: 06 Jun 13 at 9:34am
Originally posted by Daniel Holman

I suspect that as long as it is made well, more towards the small diameter/thick wall and if 2 part the join is good, that the mast will be fine with kite up and bow burying.


Surely having shrouds and a forestay would do a better job?
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Jack Sparrow View Drop Down
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Posts: 2965 		Post Options Post Options   Quote Jack Sparrow Quote  Post ReplyReply Direct Link To This Post Posted: 06 Jun 13 at 9:46am
Originally posted by tgruitt


Originally posted by Daniel Holman

I suspect that as long as it is made well, more towards the small diameter/thick wall and if 2 part the join is good, that the mast will be fine with kite up and bow burying.
Surely having shrouds and a forestay would do a better job?


Yes Dan, I'm sure thats true, based on what is known on conventional dinghies. But now imagine the repeated strain of wave piercing through steep waves on a long kite leg. As against the more conventional bow down moment on a bear away, or other less regular nose down event.

Im just interested to see what happens in some footage. And yes Tom, maybe shrouds would be a better idea if this is an issue?
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JimC View Drop Down
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Posts: 6662 		Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 06 Jun 13 at 10:11am
Originally posted by Jack Sparrow

But now imagine the repeated strain of wave piercing through steep waves on a long kite leg.

I suppose if its genuinely wave piercing and goes down and up without much increase in drag the loads ought not to be that extreme. That would be their theory anyway.

An interesting effect of lowish wings and a bow that goes down the mine a bit is what happens when the water gets back a bit further. f you aren't quite upright and the bow is well angled down then you can get to a situation where a wing tip digs in. Said wing, of course, is at an appreciable angle of incidence to the water. Either wing is good, but the windward one is especially dramatic because the boat flips straight over on you in what feels like an instant.

I am, you'll gather, speaking from experience here... I remember a mate, who watched such an event, comment that it appeared to him to have been a completely unavoidable capsize with no survival strategy.

Edited by JimC - 06 Jun 13 at 10:19am
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I luv Wight View Drop Down
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Posts: 628 		Post Options Post Options   Quote I luv Wight Quote  Post ReplyReply Direct Link To This Post Posted: 06 Jun 13 at 11:11am
The camera boat appears to be moving - in the opposite direction - to make it look faster  LOL

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Jack Sparrow View Drop Down
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to be fair Andy, the rib is only backing out of the way.
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Daniel Holman View Drop Down
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Posts: 997 		Post Options Post Options   Quote Daniel Holman Quote  Post ReplyReply Direct Link To This Post Posted: 06 Jun 13 at 12:51pm
Originally posted by tgruitt

Originally posted by Daniel Holman

I suspect that as long as it is made well, more towards the small diameter/thick wall and if 2 part the join is good, that the mast will be fine with kite up and bow burying.


Surely having shrouds and a forestay would do a better job?


A different job. A properly engineered unstayed rig will have in the order of 3 x the thickness at the base of the mast when compared to an equivalent stayed mast. That means somewhere near 20 x the inertia, so whilst the deflection at the tip with respect to its undeflected position may be greater, the stress may very well be lower.

When you load up the stayed stick you put compression into it too, which is sometimes a problem with skinny walls.

People need to get their heads around the differences between the deflections of, and stresses experienced by, unstayed masts.

The burying of the bow gives rise to an acceleration, which is what magnifies the static forces. TBH the fine bow will bury more progressively and give rise to lesser load spikes I would have thought.
Going down the mine is probably not a lot differnet to big bearaways or running aground, all events which will have associated acclelrations and load/stress spikes.

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Jack Sparrow View Drop Down
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Posts: 2965 		Post Options Post Options   Quote Jack Sparrow Quote  Post ReplyReply Direct Link To This Post Posted: 06 Jun 13 at 1:07pm
Just to make my self clear... I'm not talking about any deceleration, and that inertia affecting the mast. Im talking about the fact that the foot, kite tack and possible first third of the kite* will be submerge, potentially repeatedly, when wave piercing on a downwind leg. With the resultant repeated inversion force applied to the mast.

*the drag of the kite being submerged may add the undesirable deceleration
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haroosh View Drop Down
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Posts: 521 		Post Options Post Options   Quote haroosh Quote  Post ReplyReply Direct Link To This Post Posted: 06 Jun 13 at 5:30pm
Just watched the video and it seems quite funny to me that while loads of folks are trying to design boats to rise above the waves this boat is looking like its going to go through and under the waves!!!
The video makes it look very nose happy and indeed makes the 300 look positively buoyant in the bow.
Just not convinced about wave piercing in a small single handed craft. Does it come supplied with a snorkel set?
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getafix View Drop Down
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Posts: 2143 		Post Options Post Options   Quote getafix Quote  Post ReplyReply Direct Link To This Post Posted: 06 Jun 13 at 5:40pm
Originally posted by haroosh

Just watched the video and it seems quite funny to me that while loads of folks are trying to design boats to rise above the waves this boat is looking like its going to go through and under the waves!!!
The video makes it look very nose happy and indeed makes the 300 look positively buoyant in the bow.
Just not convinced about wave piercing in a small single handed craft. Does it come supplied with a snorkel set?


I would like to refer the honorable poster to a couple of pages earlier in this thread  Wink
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haroosh View Drop Down
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Posts: 521 		Post Options Post Options   Quote haroosh Quote  Post ReplyReply Direct Link To This Post Posted: 07 Jun 13 at 12:49pm
Ah fair enough. Didn't look back. Too busy keeping up with all the 100 owners post tennis!!!
Keith
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