New Age Trawler/Motorsailer; Kite assisted PowerYacht

[Tad]

Originally Posted by brian eiland

it doesn't sound as though it would be that much more difficult to build the 'electronic control unit' for the "easing lines" than to build a good electronic autopilot??

The brains are cheap and easy.....it's mechanical parts that get difficult. Which is why this is not common.

I believe the kite has 4-5 control lines. In a big heavy cruising boat these lines are under high load at times. These lines must be long, and quickly and infinitely adjustable. This means a bunch of captive reel winches (heavy, complex, expensive) run by a computer. Fine for the engineers in the crowd. The typical cruiser is crewed by a relatively feeble retired couple, not a young athletic crew out for a daysail.

[brian eiland]

But Tad I believe this is a major difference with the 'older' idea of flying the kites...multiple lines to the vessel. The Skysail system sheets its line to the control pod that is tethered to the vessel by a SINGLE line. The control pod handles the flying of the kite without resorting to, " a bunch of captive reel winches (heavy, complex, expensive) run by a computer".

You don't steer the kite by sheeting in against the pull, you steer it by dumping lift off the side toward which you want the kite to go. Easing lines, not sheeting in

[Tad]

So........

The Sky Sails system consists of...at least...

A "Kite", which they say is cheap.

A "Control Pod", unique in the world....not cheap, not fixable by joe the plumber.

A "towing rope", specially braided with control and power cables included...definitely not cheap.

A "Force transmission point", again unique in the world, hydraulic or electric powered.

A "winch", unique to the application, custom unit.

A "control unit", (computer) semi-custom software is not cheap in my experience.

A "launch and recovery system", again custom hydraulics with electronic controls.

All of the above is somehow cheaper and easy to repair and maintain than a mast and a sail?

[brian eiland]

Didn't say it was going to be cheap, but might offer unlimited range without being a 'sailboat'.

And from my very first posting on this subject thread:

Originally Posted by Brian

Only two engines and no conventional sailing rig should make this a more affordable vessel, both in construction, in maintenance, and in operation. However the SkySail kite arrangement will probably more than offset the conventional sailing rig in cost. Possibly a less expensive alternative to this ‘brand name’, with less computerization could be found (no integrated weather/navigation features, etc)

Might be rather exciting to own the first one as well

[apex1]

Originally Posted by brian eiland

Might be rather exciting to own the first one as well

That´s too late, there is at least one yacht under construction at present with a "Skysail" system.

TAD, I completely agree with your comments above. But we have just to be more patient to see affordable and comparable prices. "Skysail" started production of the first sets just hours ago.

Regards
Richard

[eponodyne]

Originally Posted by brian eiland

I don't truly know at this stage, Guillermo, but I did find this quote interesting.


So it doesn't sound as though it would be that much more difficult to build the 'electronic control unit' for the "easing lines" than to build a good electronic autopilot??

I've actually been thinking a gyroscope control might be the way to go. The technology is certainly available and proven. Would probably not be too badly affected by the shock loads encountered on a boat (rarely over 1G, as opposed to what they endure in aircraft). So an electro-mechanical device, with bellcranks and pushrods. Might as well do it in bronze, with black enamel filigree work. Some crazy sort of Difference Engine providing negative feedback. It would probably work well enough in steady winds to keep the kite more or less where you want it.

There really isn't much shock absorption going on with the kite and the lines, again probably due to the low mass of the vessel (More, in my case. I daresn't wear my regular wetsuit due to an overweening love of Carbohydrate Surprise With Extra Butter) allowing a bit of leeway to happen as the kite takes a greater load. Remember, though, that the kite is in point of fact tied to the rider through a seat/belt harness, to transfer load through the rider's CG. The same arrangement would be enough to get a boat going, though I suppose a cautious man could make up a lizard out of like 12mm nylon 3-strand to act as a snubber of sorts.

By the bye, I had what happens with the kite, to turn it, crossed up. Shove left to turn right; shove right to turn left.

[Fanie]

I flew my friends sports kite before. One thing I was interested in was if it can fly to wind like a sail. It can and pretty well too.

I was under the impression it had four lines, and I asked him a couple of nights ago, but he says no, it only has two lines, similar to the Peter Lynn's
kites. If your arms get tired you can park and hold the kite right above your head, then drop it when you got your breath back. Good exersize when the wind is really up

As for shock absobsion, would one really need it ? Sails have no shock absorbsion other than accellerating the boat or heeling, and also it seems in a gust the kite tends to fold up some, kind of like tending to bringing it's arms closer together.

Electronic controlls is not going to be that difficult, although probably not as cheap as someone commented, but that depends how a reliable system you build. If the control module is allowed to hinge on deck you can get a direction feedback wrt the angle the kite is wrt the boat. The lines angles wrt to the horizontal is another indication of where the kite is. So even if at night and you cannot see the kite at all, all the indications can be made visible with electronics.

The automated control for flying a kite can be made easily if you use the electronic feedbacks for control and use some engineering things commonly in use on machinery, a motor driving a rack and pinnion or a nut and acme thread are both mechanical forces for control. Mechanical arms etc can still be good old stainless steel.

Getting the kite up also doesn't have to be that difficult. If you drive into the wind using the iron sails you probably won't need much speed to get it up. It does however require a bit of fuel.

The only unknown is when the wind dies down or when you encounter a change in wind direction. A radical change in wind would bugger the kite up for sure, which may require retreival and untangling. Would probably happen at night and under the worst of conditions too

[brian eiland]

Originally Posted by apex1

That´s too late, there is at least one yacht under construction at present with a "Skysail" system.

Which one is that?

[brian eiland]

Originally Posted by eponodyne

..Second, that they must be kept flying by waving them all over half creation: Well, kind of.

I think there is some misunderstanding here. One of the reasons the kites are 'flown' in an exaggerated manner is too be able to extract more pulling energy from them per square foot area...more power from a smaller kite.

Remember the old theorem, the pressure goes up as the square of the velocity of the wind. So if you fly figure-eights the kites can develop substantially more power/sq ft.

[apex1]

Originally Posted by brian eiland

Which one is that?

I was shure that question would come.
Sorry. agreement of non disclosure.

Regards
Richard

[rob denney]

G'day,

When we flew the 420 sqm Outleader in little or no air, we found that a helicopter hovering off the back of the boat was enough to get the kite up, but not keep it up. As soon as the boat started to move, apparent wind came forward and it collapsed. With a little more crew ability, it would be posible to sail on a reach so that the apparent was helping, not hindering. So, a blower could be a handy gadget in marginal conditions, although the work required to keep the kite flying in these conditions would probably not be worth the effort for cruisers.

The figure 8 stuff is not necessary on cruisers, nor when going to windward. In fact, the figure 8 is one of the big things holding back big boat use. Power increases by the square of the windspeed, so if the kite is flown across the sky, it can quadruple it's apparent wind, with enough power increase to rip winches from the deck.

Outleaders are self stabilising, if set up properly. To trim them, you ease the corner that is heading for the briny. If the lines are far enough apart, as the kite dives, the sheet on the diving corner gets longer, the kite stabilises. Works well on cats with the wing lines on the gunwhales amidships and the tail line on the fore beam.

They cannot be parked, and are a big nuisance if they fall in the water. However, this should (note the should;-)) only occur in lightish winds as in a good breeze, the collapsed kite streams downwind.

Kites are the rigs of the future, but there is a way to go before they replace sticks and sails. Fortunately, there are a lot of very clever people working on them, so it is only a matter of time, and overcoming boat owners' conservatism.
regards,

Rob

[Guillermo]

Originally Posted by apex1

I was shure that question would come.
Sorry. agreement of non disclosure.

Regards
Richard

There was that Humphrey's designed trimaran, wasn't it?

[apex1]

Originally Posted by Guillermo

There was that Humphrey's designed trimaran, wasn't it?

You said that Guillermo. Not me

[Boston]

Originally Posted by eponodyne

I've actually been thinking a gyroscope control might be the way to go. The technology is certainly available and proven. Would probably not be too badly affected by the shock loads encountered on a boat (rarely over 1G, as opposed to what they endure in aircraft). So an electro-mechanical device, with bellcranks and pushrods. Might as well do it in bronze, with black enamel filigree work. Some crazy sort of Difference Engine providing negative feedback. It would probably work well enough in steady winds to keep the kite more or less where you want it.

There really isn't much shock absorption going on with the kite and the lines, again probably due to the low mass of the vessel (More, in my case. I daresn't wear my regular wetsuit due to an overweening love of Carbohydrate Surprise With Extra Butter) allowing a bit of leeway to happen as the kite takes a greater load. Remember, though, that the kite is in point of fact tied to the rider through a seat/belt harness, to transfer load through the rider's CG. The same arrangement would be enough to get a boat going, though I suppose a cautious man could make up a lizard out of like 12mm nylon 3-strand to act as a snubber of sorts.

By the bye, I had what happens with the kite, to turn it, crossed up. Shove left to turn right; shove right to turn left.

how about a pendulum system to alter the center of gravity and turn the kite back and forth
could be a simple wound spring unit with watch gears and a wireless servo to adjust the swing of the pendulum and so the size of the figure eight
one simple radio control unit and a power winch
regular old line

launching and recovering it would be the fun part
but once its in the air in a steady breeze

skimmed this thread
what a great idea

[masalai]

That is how I understand the "commercial" control system works with an electronic control winding up on one side and out on the other to direct the kite in a manner to maximise the towing effort with just one main "springy" line to absorb the rise and fall of the bow so the kite does not deflate... a fairly simple exercise basically moving the control ballast across the junction or the individual control lines to the "pendulum", to which is attached the prime tow rope...