heady times

[Gary Baigent]

The big, big, astonishing hard sail rig on BMWOracle - and now Hydroptere has just covered a mile at an average speed of just over 50 knots .... think of that, chaps, 50 ks for a mile, fargo truck!

[Doug Lord]

What does "fargo-truck" mean? You're right-extraordinary times:

[Gary Baigent]

Polite way of saying ******* awesome.

[jamez]

God-damn Ethyl thats what I call me a wing-mast. Deja-vu Gary??

[sailsocal]

This boat looks absurdly overpowered, I will bet money that it will capsize while racing. Wouldn't two shorter wing sails be a better solution? Same power, lower center of effort?

[boat fan]

This boat looks absurdly overpowered, I will bet money that it will capsize while racing. Wouldn't two shorter wing sails be a better solution? Same power, lower center of effort?

Not the same amount of power I`m afraid...tall high aspect wins........

[sailsocal]

Not the same amount of power I`m afraid...tall high aspect wins........

I don't follow your point. Obviously, if they added a second IDENTICAL wing sail to the boat, it would have more power than with a single sail. Then if both masts were progressively shortened, at some point the two shorter sails would yield the same power as the original single tall sail, but with lower center of effort.

[ancient kayaker]

I don't follow your point. Obviously, if they added a second IDENTICAL wing sail to the boat, it would have more power than with a single sail. Then if both masts were progressively shortened, at some point the two shorter sails would yield the same power as the original single tall sail, but with lower center of effort.

-and more drag.

[sailsocal]

-and more drag.

I suspect that the boat is so overpowered that the lower center of effort with a dual wing rig might outweigh any decrease in lift/drag coefficient of two shorter sails.

Maybe Tom Speer can shed some light on this question?

[boat fan]

The simple truth is a high aspect rig is faster ...every time.

That`s why they use them for racing craft.

Nothing better has yet been devised with multiple rigs.

Less weight too and ...
Less drag...and....
most likely , less cost...( possibly ) ...

Link to Sailcalc software program :

http://www.google.com.au/url?sa=t&source=web&ct=res&cd=2&ved=0CA8QFjAB&url=http%3A%2F%2Fwww.wb-sails.fi%2Fnews%2FSailPowerCalc%2FSailPowerCalc.htm&rct=j&q=high+aspect+rigs&ei=K-79SrbRI5L8sQO7-dmHCw&usg=AFQjCNH5fdTEa6WWPaY6Lte98gxsFvsuMw




Aspect ratio

The rig aspect ratio affects the pointing ability of the boat. A taller rig produces more drive at a given wind angle and for the same sail area than a lower one. Try a very high aspect ratio P= 17.35 m E= 5.00 m, and compare with the default rig (Reset). There is a catch with high aspect ratio - heeling moment goes up - this puts a practical limit to the tallness of the rigs we use on contemporary boats.



Nothing new here ....

[ancient kayaker]

The rig in post #2 reminds me of the rigs used for ice boats. The design drivers of ice boats are different, at high speed the primary drag is aerodynamic not hydrodynamic and there is little price to pay for added beam, at least for straight-line speed. So the drive needed to attain high speed is not hard to achieve and they can be made to move faster closer to the apparent wind if aerodynamic drag can be kept low enough. There is less drag if the pilot stays inboard so there is no hiking, that allows control of a more complex rig, hence the very tall ultra-low drag rigs with variable slot or profile. Just steering, the alpha angle and slot to control.

All that's very like what we see in the pictures of post #2. Can the technology migrate successfully to a boat? It would have to be big and have lots of beam, again just like the boat in the picture. So the real question that remains is, can the hydrodynamic drag be kept low enough to take advantage of that rig? There's gotta be foils underneath all that or the gains will be marginal at best ...

[Samnz]

This boat looks absurdly overpowered, I will bet money that it will capsize while racing. Wouldn't two shorter wing sails be a better solution? Same power, lower center of effort?

They wont tip over theyre pros, only idiots who forget to ease the main or tangle the kite sheets capsize.

the BMW Oricle tri is bloody awesome, and i think theyve still got plenty of potential to unleash!

[sailsocal]

They wont tip over theyre pros, only idiots who forget to ease the main or tangle the kite sheets capsize.


Yeah, right :rolleyes:

http://www.boatdesign.net/forums/multihulls/transat-jacques-vabre-capsize-30080.html
http://www.liveyachting.com/alinghi-x40-catamaran-capsize-opps
http://www.sailkarma.com/2008/12/hydroptere-capsized.html

[ancient kayaker]

Doug: where did those images come from? The only pics I find on Oracle show it with a regular looking fabric jib and and heavily battened but conventional looking fabric mainsail. I know there is a wing sail in the works or on the way or something but I wouldn't think they could have got it installed so soon. Or are those pics artist's impressions?

[Doug Lord]

Doug: where did those images come from? The only pics I find on Oracle show it with a regular looking fabric jib and and heavily battened but conventional looking fabric mainsail. I know there is a wing sail in the works or on the way or something but I wouldn't think they could have got it installed so soon. Or are those pics artist's impressions?

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One was off the Oracle site(I think) and the other from the SA AC thread-plenty of pictures there.