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On DeckMovable Ballast

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Doug Lord View Drop Down
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Post Options Post Options   Quote Doug Lord Quote  Post ReplyReply Direct Link To This Post Posted: 18 Sep 05 at 3:45pm
Don't focus too much on the electric option-the standard design would be manual-even though the electric system(with manual backup) could be made to work very reliably.
"Movable ballast on the wrong side pinning the boat down" . If you reread the previous post you'll notice the part about more buoyancy in the wing than weight.
But no matter how well designed there are conditions that will be too much for this boat-or any boat. Since the concept works on model boats the next step is to-sometime- build one and test it- the fun potential is there as well as the high performance potential with or without a keel.
I'm interested in seeing what Bethwaite comes up with in his "LAS"-lead assisted skiff- which, as I understand it, is being looked at for the 2008 Paralympic's.
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Stefan Lloyd View Drop Down
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Post Options Post Options   Quote Stefan Lloyd Quote  Post ReplyReply Direct Link To This Post Posted: 18 Sep 05 at 3:16pm

Hm....have you had much actual experience with boat electrics or keelboats?

Electrics fail all the time, even on bigger boats, let alone something as wet as you are proposing.

Anyone who has sailed high performance keelboats for very long has had the experience of them not self-righting, even without the benefit of moveable ballast on the wrong side pinning the boat down.

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Post Options Post Options   Quote Doug Lord Quote  Post ReplyReply Direct Link To This Post Posted: 18 Sep 05 at 2:55pm
This idea won't produce a skiff necessarily -just a high powered dinghy.
In the states the Martin 16 uses electrical components for handicapped assistance very successfully-not to mention all the ocean racers using electric winches or electric based canting keel systems(Schock 40); there have been tremendous advances in making that stuff work extremely well in a harsh environment.
The initial concept includes a weighted daggerboard -the boat would be self righting . In a worse case scenario with the wing fully extended: if the wind quit there is more buoyancy in the wing+ buoyancy pod then there is weight; If the boat was capsized it would right itself. At least when sailed in it's "safest" mode. It could, theoretically, be sailed without the keel weight and still be rightable by an able bodied person.
Whether the ballast is moved electrically or manually it is possible to design a system that moves the weight from max extension to center in one second-faster than a normal "crew" could move.91kg. of ballast with a CG at 2.43m from the CL at max extension is a lot of RM. Further, the ballast is adjustable, is never late, does exactly what you want done when you want it done and, most importantly, MOVES FAST.. A "robocrew" that makes this a potentially exciting singlehander.
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Stefan Lloyd View Drop Down
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Post Options Post Options   Quote Stefan Lloyd Quote  Post ReplyReply Direct Link To This Post Posted: 18 Sep 05 at 8:34am

What happens when you capsize with the ballast on the "down" side (which is going to happen sooner or later)? OK, so you have flotation, so the boat doesn't actually sink, but how do you right it?

You actually need quite a lot of flotation to generate 170-200kg. It would be bulky.

Electric power and dinghies in salt water - sure - that will work for about 5 minutes.

Isis's point about the need for righting moment to be dynamic is also a very good one.

 

 

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Post Options Post Options   Quote *GM* Quote  Post ReplyReply Direct Link To This Post Posted: 18 Sep 05 at 12:15am

Hmmm, the SA discussion was quite amusing....

http://www.sailinganarchy.com/forums/index.php?s=440dddfceb2 6731d34c7d88be63fd538&showtopic=23407

 

What's it rate...........

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ssailor View Drop Down
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Post Options Post Options   Quote ssailor Quote  Post ReplyReply Direct Link To This Post Posted: 17 Sep 05 at 9:14pm
true, not only that, the idea of a high performance boat is that its your weight keeping it flat therefore they dont weigh much, so i feel it wud be good but not quite a skiff!
Any one in need of quality carbon fibre work (tillers etc) at decent prices!

Int 14 Gbr 1244 'Nucking Futs'

The New Port rule!!.
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Isis View Drop Down
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Post Options Post Options   Quote Isis Quote  Post ReplyReply Direct Link To This Post Posted: 16 Sep 05 at 9:53pm
Its a nice idea opening the high performance realm to those who, for whatever reason, just arent agile enough to sail the available boats but for the same reason that they cant sail them at the moment I dont think it would be sucsesfull. High performance boats are very dynamic boats to sail. Thier design means they have very little static stability and you are constantly moving about responding to the boats movement. Whilst the principle obvoisly works on a small scale i dont think you would get enough  responce from the balast to make it sucsessfull in the 'real world'
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Doug Lord View Drop Down
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Post Options Post Options   Quote Doug Lord Quote  Post ReplyReply Direct Link To This Post Posted: 16 Sep 05 at 8:51pm
I've been tossing this around for a while: what about a 16-17' fairly high performance dinghy designed so that the skipper sits down in it like a mini 12 but with a difference: the majority of ballast would be in a"wing" between 6 and 10' long and would slide side to side either by electric power or by the crew using a "bicycle winch":leg power moves the weight(weight about 170-200 pounds). The whole wing would move side to side along with a weight sliding on it so the CG of the movable weight could get up to 8' or so from the CL of the boat.The wing would be supported by "Trapeze" wires. The wing and the crew seat would be somehow tied together so that the crew could slide aft as necessary and/or the boat would be equipped with a rudder t-foil.
There would be a deep daggerboard(retractble) with some weight on it- and the ends of the wing would contain buoyancy pods to help prevent a permanent capsize.The hull would be fairly narrow and the wing would pivot for trailering or stowage.It would have a spinnaker...
These are pictures of an rc model with such a system on it:
http://www.microsail.com/pictures/m24c5.jpg

http://www.microsail.com/pictures/m24c6.jpg

The concept is to allow high performance without the physical requirements of most dinghies in order to open up the thrill of performance dinghy sailing to people that for whatever reason don't want to or physically can't hike or use a trapeze.
I'd really like to hear comments...
=================
Edited to try to determine why the url's here are "live" and the one on my last post is not...

Edited by Doug Lord
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