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catty · 21-11-2011, 02:41

Quote:

Originally Posted by estarzinger

True in theory . . . but the wind direction is not constant,

There was a previous wing sail cat - walker wing sail - they also found this (more lift and drag when feathering than expected).

Yes, years ago we shared a marina with a tri equipped with a walker wing sail.
It was interesting watching the whole shooting match responding to the wind shifts generated by the tall surrounding apartment buildings.

It certainly generated some discussion amongst us on the outcome in a blow, whilst watching it tugging at its mooring lines.

I suppose if Chris keeps the lubricants up to the foil bearings the perpetual foil movement won't drive him totally nuts.

Regards

H.S.Hemingway · 21-11-2011, 09:39

I remember the Walker Wing-sail, but what I think the big draw back of that and the modern Amercas cup designs is the momentum of the wing to react to changing wind directions.

the mass of this big wing-sails is much higher and much more off the center of rotation => bigger momentum

as from an engineer background i would expect the wing-sail of the A47 to react much quicker and with much less drag and lift.
as far as i have understood it from Chris' site there must be some bearings to allow the wing to freely move around a non rotating mast.

to me this really looks good as a simple cruising rig which my wife could handle easily without help of hoisting/reefing the main sail

therefore more sleep for me during the night

colemj · 21-11-2011, 14:40

Quote:

Originally Posted by H.S.Hemingway

therefore more sleep for me during the night

Maybe not - depends on how quiet this can be made. The smallest movement of a conventional boom can cause "squeak, squeak, squeak" and keep you up all night.

Mark

H.S.Hemingway · 21-11-2011, 20:13

Quote:

Originally Posted by colemj

Maybe not - depends on how quiet this can be made. The smallest movement of a conventional boom can cause "squeak, squeak, squeak" and keep you up all night.

Mark

Hei Mark, yes I know what you mean and I was not referring while anchoring. But anyway I will love those sounds

as compared to the traffic noise I have hear in Nairobi in front of my windows.

What I meant is the easy principle of reefing/furling the jibs and de-powering/ powering the foils.
This will be easily possible to be done by my wife. In a larger boat she has just not the physical strength to deal with all that. And while on nigh watch I would need much less to worry about the right amount of canvas up in the wind.

Therefore for me this would be a perfect cruisers rig if all works out as stated by Chris. And I think it does, as Chris has a huge amount of experience and if you read a bit more in deep about the experience of owners of his designs I was not able to find a negative comment about his boats. I'm sure this system is well thought and it will work.

Cheers
Olli

zeehag · 27-11-2011, 10:26

if your boom is making squeaking noises you havent maintaines the gooseneck properly with good grease annually.

there was and still is trimaran in harbor island for decades with same rig i saw on the ac boat that was berthed near me. i dont see how the man of the ac boat can claim ownership of patent unless the man who designed the one on trimran is either dead, his relative, or that he bought rights from him, or unless he designed that particular one as well../ the tri has been in spanish landing looong time, and sails on sd bay infrequently. i saw no difference whatsoever in operation between the 2 rigs, however the ac rig was skinnier and taller than the trimaran rig..both seemed to function in same way.

Dogfish · 28-11-2011, 17:13

From the Chris White Designs website: "Pinned to the dock by a 30 knot wind on the beam? We think that by trimming the MastFoils opposite each other that enough sideways lift can be created to actually pull the boat away from the dock! Try doing that with a conventional rig."

This part interested me. Can someone explain to me how this could possibly work? If that were the case, couldn't one mount two wing masts side by side and sail directly into the wind?

catty · 28-11-2011, 18:41

Quote:

Originally Posted by Dogfish

From the Chris White Designs website: "Pinned to the dock by a 30 knot wind on the beam? We think that by trimming the MastFoils opposite each other that enough sideways lift can be created to actually pull the boat away from the dock! Try doing that with a conventional rig."

This part interested me. Can someone explain to me how this could possibly work? If that were the case, couldn't one mount two wing masts side by side and sail directly into the wind?

It can't. Just like a lot of the stuff written by CW in that article it just doesn't stand up to any scrutiny.

Ted Spears has contributed to a thread on Boatdesign Forum, regarding this very issue.

Regards.

Dogfish · 28-11-2011, 18:51

Will look for that, thanks.

catty · 28-11-2011, 18:59

try here......MastFoil, opinions? - Boat Design Forums

and here......MastFoil™ on the Chris White Designs Atlantic 47 - Sailing Anarchy Forums

Regards

**s/v Jedi** · 28-11-2011, 19:00

We have friends that own "Angel B", a trimaran with Walker fixed wing. They completed a world circumnavigation with it, incl. the perfect storm conditions on the Indian Ocean without any wing trouble.

Their boat is joystick controlled and going sideways is not a problem. Also, staying in a marina in storm conditions proved a non event to the disappointment of many who came to look :-)

I would be very scared for water spouts, white squalls, micro cells and downdrafts so I'll keep it to the canvas type of sails

ciao!
Nick.