Sailors wrong for thousands of years?

[wardd]

Originally Posted by sharpii2

Now that I have thought of it a bit, a wind turbine boat would have a few advantages.

1.) it is probably the only type of wind powered boat that can sail directly upwind,
2.) it needs very limited draft. Just enough to keep the prop from ventilating and for an adequate rudder, and
3.) It is probably the only wind powered boat type that can automatically 'reef'. Like a Jacobs wind turbine of the '30's, its blades can be mounted with springs and worming, so that greater RPM causes the blades to automatically feather. I read of one Jacobs that had been up for more than 30 years and went through two hurricanes and was still kicking out the watts.

That being said, I can see a few disadvantages.

1.) It would almost certainly be more expensive than a decent sailboat (which can not sail directly into the wind, but, under most circumstances, get there). The blades have to be carefully designed and balanced, a long drive shaft has to go up the mast and must be able to withstand some pretty high torque. To keep the weight down, I suspect some pretty expensive materials will have to be used,
2.) getting hit by a boom is bad, but nothing like being hit by a blade (this was Phil Bolger's major objection), and
3.) failure at sea could be uncommonly catastrophic. Imagine one blade flying loose from the hub. The other two could shake the structure to pieces. And even if it didn't, jury rigging could be quite difficult. And it's also a matter of luck where the loose blade goes. Being out on a rolling sea, with the boat pitching, yawing, and rolling, I believe could only heighten the chances of this happening. Such could put the blades through some interesting bending cycles.

I imagine such a machine would be most useful where straight sailboats fear to tread. Long winding narrow waterways where there is often no option but to go dead upwind. Such waters tend to be flatter than the open sea, so my third objection could be removed. The first could be justified by the need to go dead upwind and the second could be done away with by putting up a strong roof between the blades and the occupants, strong enough so a loose blade could not smash through.

I think, over long periods of time, snap rolls would be the worst enemy of this sort of set up. I suppose I would use either a dead rise hull or one with a narrow flat bottom and considerable flair to its sides. The gyroscopic effect of the blades could further dampen the roll, except when sailing dead upwind. Perhaps the hull development would need as much or more consideration than the machinery and blade design.

no reason the mast couldn't be the shaft

[Windmaster]

From time to time, the vertical axis idea gets mentioned. The main attraction, being of course, that you don't need to orient it to the wind.
However, there is no case where a boat, or indeed a land vehicle has ever been able to travel directly to windward with one, and without this ability, the main attraction and indeed advantage of a rotary sailing power is lost.
It's not difficult to see why a vertical axis setup does not work directly to windward when you consider that the blade on a horizontal axis machine may achieve a lift to drag ratio of as much as 50 to 1 (50 times the lift for one of drag). This makes for super efficiency in that the rotating force (which we use to power the boat) could be 50 times greater than the drag which is tending to hold the boat back. By contrast, the drag of a vertical axis arrangement is considerable. True, they have been used successfully on land-based power generation turbines, but on a fixed base system the drag is of no importance since it does not matter how much you push the ground - it's not going to have any negative effect!

[Dave Gudeman]

Originally Posted by Windmaster

From time to time, the vertical axis idea gets mentioned. The main attraction, being of course, that you don't need to orient it to the wind.
However, there is no case where a boat, or indeed a land vehicle has ever been able to travel directly to windward with one

Has anyone ever tried? I'd be interested to know more about any such attempts.

It's not difficult to see why a vertical axis setup does not work directly to windward when you consider that the blade on a horizontal axis machine may achieve a lift to drag ratio of as much as 50 to 1 (50 times the lift for one of drag). This makes for super efficiency in that the rotating force (which we use to power the boat) could be 50 times greater than the drag which is tending to hold the boat back. By contrast, the drag of a vertical axis arrangement is considerable.

I don't follow this. The force that would be applied to the wheels to make the land vehicle move forward would be determined by the gearing; not directly by the lifting force on the blades. Unless the drag is so much that it is causing the wheels to lose traction, the only effect is that you require a slightly lower gearing which would cause the vehicle to move a bit slower.

The case is different on a boat, of course.

[Windmaster]

Originally Posted by Dave Gudeman

Has anyone ever tried? I'd be interested to know more about any such attempts.

I don't follow this. The force that would be applied to the wheels to make the land vehicle move forward would be determined by the gearing; not directly by the lifting force on the blades. Unless the drag is so much that it is causing the wheels to lose traction, the only effect is that you require a slightly lower gearing which would cause the vehicle to move a bit slower.

The case is different on a boat, of course.

The only attempt I have seen is one of the entries in the landcart "wind energy events" which have been taking place in Holland and Denmark in the last few years http://www.windenergyevents.com/Race2008/index.html I have seen some video footage of one of the entrants with a vertical axis turbine. The shot shows a team of people pulling a rope to get the rotor up to speed before (presumably) setting it on its way directly to windward, but there is no view of it actually proceeding in the required direction. That's the only time I have seen any evidence of an attempt, and since I am sceptical that it would work, I don't want to spend a lot of time and energy on it myself. But anyone else is welcome to try!

On the point about the gearing, yes, that is true that you could gain mechanical advantage by gearing down. However, you are still facing a pulling match between the drag holding you back and the rotating force which you want to use to push you forward. You would have to gear down a whole lot, which would (IMHO) result in creeping forward minimally in a very impractical way. In the case of a boat, it is not so very different actually.

[Jack Hickson]

Originally Posted by Windmaster

From time to time, the vertical axis idea gets mentioned. The main attraction, being of course, that you don't need to orient it to the wind.
However, there is no case where a boat, or indeed a land vehicle has ever been able to travel directly to windward with one, and without this ability, the main attraction and indeed advantage of a rotary sailing power is lost.
It's not difficult to see why a vertical axis setup does not work directly to windward when you consider that the blade on a horizontal axis machine may achieve a lift to drag ratio of as much as 50 to 1 (50 times the lift for one of drag). This makes for super efficiency in that the rotating force (which we use to power the boat) could be 50 times greater than the drag which is tending to hold the boat back. By contrast, the drag of a vertical axis arrangement is considerable. True, they have been used successfully on land-based power generation turbines, but on a fixed base system the drag is of no importance since it does not matter how much you push the ground - it's not going to have any negative effect!

Tried vertical axis on a wind generator once . Useless. The non driving one was strictly drag. With a blade, both provide power full time.

[hawkerdonkey]

Hello to all,

I've very much enjoyed reading the banter on this particular subject and my $0.05 would go to this beauty:

One Rebuit Retractable horizontal drop down
Type Wartsila Lips CS1500-250 MNR
Power Rated 1550 KW
Motor Speed 1000 rpm
Prop. dia. 2300 mm
Stem Length
Drive Horizontal
Motor voltage 690
Status Rebuilt
Class Lloyds
Mounting Under water mountable
Available now
Warranty none
Includes motor and control gear, couplings
Installation drawing available
Lloyds cert available

from this guy http://www.maritimeequipment.com/ShowAd.aspx?id=107341

He has a lot of other heavy metal too. Connected to a slow turning, correctly calculated windmill (blade-Tip ratio et al) and plant it at the back of something like this for fuel conservation purposes http://www.jameslist.com/advert/8816...i-di-pisa-30-s

All within budget and delivered before the deadline

While we're at it, I still haven't found a marine application to these yet (jet?) but at the tip of the blades, on a calm day should cause a bit of a stir I recon.

http://www.tecaeromex.com/ingles/RH-i.htm

Toodlepip,

Honkey!

[nate teach]

so what happens when the wind is coming from behind you?

[hawkerdonkey]

http://www.youtube.com/watch?v=5Ccgm...eature=related