New Age Trawler/Motorsailer; Kite assisted PowerYacht

[eponodyne]

Originally Posted by juiceclark

Brian,
The guy who owns the local windsurfing shop is a friend of mine and likes to tinker with stuff. We've been meaning to experiment with something on my F-36 Trojan but the damn boat doesn't have a davit. So, we were gonna rig something from the bridge...not sure how. I'll have to replace the windlass rode as well to experiment with a small kite...something lighter. If I had a windlass with a horizontal capstan, it could be done manually without worrying about being taken swimming....but I don't.

http://i246.photobucket.com/albums/g...k/IMG_0590.jpg

http://i246.photobucket.com/albums/g...HorseNew-1.jpg

If I were you... and I'm not... but if I were you, I'd install a big husky pad-eye just forward of the mast. A good Christian piece of equipment that can take a serious pull (you may find it useful for other things in the future, as well) and just use that as the attach point for the chicken loop on the kiteboard rig. Bend on a couple 1/2" lines, one to each end of the bar, and lead them back to the cockpit, so you can sit down in comfort while you fly the kite. I'd leave the sheeting loop all the way out and fly the kite depowered until you're sure you know what you're doing and wish to sheet in a little more.


I assume you have 30 foot or so of surplus half-inch (or thereabouts) nylon.
Shouldn't cost you much more than a hundred bucks for the padeye, installed. Maybe ten more for a nice stainless shackle.

[juiceclark]

Brian and Epo,

Thanks for reminding me of this subject. I stopped by the surf shop on the way home for lunch and he just happened to have a 20 meter kite sail a guy just traded in for a new design...couple hundred bucks out the door. It looks like this but without the hideous graphics:
http://www.kite-line.com/kiteboardin...ils.php?i=1342

I'll have a lot of fun this weekend playing...can't wait to get people watching then put the engines into gear. I'll be running 18k on a plane with sail up just to freak out the blue hairs.
Epo is right...I'll have to install some type of eye or pulley mid-boat. Then I'll sit at the bow to release and retrieve the 100' of superlight 5/8th" line I just bought. I'll take some pics and post. Please call the CG if you don't hear from me by Tuesday!

If this works out well, we'll try my neighbor's 48' powercat next with this type of deal:
http://www.kit-cats.com/kite/KiteSailPowerboats.htm

[brian eiland]

Originally Posted by juiceclark

...Epo is right...I'll have to install some type of eye or pulley mid-boat. Then I'll sit at the bow to release and retrieve the 100' of superlight 5/8th" line I just bought. I'll take some pics and post. Please call the CG if you don't hear from me by Tuesday!

Brian wrote: Don't understand your need to 'anchor' your pulling point at mid-boat...why not at the bow??
http://www.skysails.info/index.php?id=8&L=1

http://www.skysails.info/index.php?id=46&L=1
Force Transmission Point (tow point)
The "force transmission point" - also called "tow point" - is the point at which the towing rope of the kite is connected to the ship.

The tow point guarantees the optimal alignment of the kite's power for every course and wind direction.

The tractive force of the SkySails-System is directed to the bow area over the force transmission or tow point mounted on the foredeck. Generally the existing ship's structures are sufficiently dimensioned, since that is where the capstan and anchor windlass are also housed. The power transmitted by the SkySails-System is comparable to that of an ocean-going tug. An appropriate stability computation is made for each vessel prior to the installation of a SkySails propulsion.


Brian wrote: It's the winch and tower for inflating the kite that are located further aft to facilitate the inflation of the kite over the foredeck rather than out over the front of the bow

Winch
The SkySails towing kite is recovered and launched using a dynamically operating winch, which also serves as rope storage. The tractive force measurement is pre-installed in the winch. The winch speed is chosen so that the towing kite can be stabilized at any time.

Launch and recovery system
The launch and recovery system manages the deployment and lowering of the towing kite and is installed on the forecastle. During launch a telescopic mast lifts the towing kite, which is reefed like an accordion, from its storage compartment. At sufficient height the towing kite then unfurls to its full size and can be launched. A winch releases the towing rope until operating altitude has been reached. The recovery process is performed in reverse order.

[juiceclark]

I figured if the "force transmission point" was right at the bow it would have a levered action in pulling the bow around. Further after, say just in front of the salon windows, would eliminate some of that. But as you know I'm a finance guy not a naval engineer! If I want to go to 12 o'clock and the wind is blowing 2 o'clock, wouldn't it be easier to keep my heading with the connection further aft?

If I can just connect this thing at the bow it's a no-brainer! There are all kinds of cleats with an eye in the middle and other things already up there to use. I have fairly sizable rudders and some keel to stay on course. Is that enough or am I way off course?

[eponodyne]

Originally Posted by juiceclark

I figured if the "force transmission point" was right at the bow it would have a levered action in pulling the bow around. Further after, say just in front of the salon windows, would eliminate some of that. But as you know I'm a finance guy not a naval engineer! If I want to go to 12 o'clock and the wind is blowing 2 o'clock, wouldn't it be easier to keep my heading with the connection further aft?

If I can just connect this thing at the bow it's a no-brainer! There are all kinds of cleats with an eye in the middle and other things already up there to use. I have fairly sizable rudders and some keel to stay on course. Is that enough or am I way off course?

I really don't think it's going to be, on a moment that long. I'd really think you want to keep your load centered around the mast, which should be about, what, 4 feet forward of the LCP for your existing sail plan? Something like hat? Anyway, I really don't think you want to try to fly the kite off the bow. I really don't.

[juiceclark]

Agreed. I'll attach the kite at a point near the salon window...probably about 5 feet fore of center. With a relatively puny 20m kite I can stand anywhere on the bow to mess with it. If it seems steady at a certain height, I'll go back to the flybridge to see how everything reacts.
TC

[eponodyne]

Well, if you can find a breeze in South Florida in August, the 20 should be able to deal with it. If the wind pipes up, that kite might just kick your ass. That's 200 square feet developing 3-6 pounds of lift per square foot; and it goes up as the windspeed goes up.

Have you flown kites before? Like stunt kites and traction kites and like that? I cannot stress enough that you spend a lot of time--like a hundred hours or so-- just flying kite in the park or at the beach. If you have done this, then you'll understand my caveats; please forgive me. If you haven't, be aware people have been killed playing with big kites. They're a lot of fun but you need to know what you're doing.

[Fanie]

My friend has a 1.5m stunt kite I flowed once. In wind like in 'it blowing now' you have to hold on well to this thing. Good way of getting rid of children

[Munter]

Originally Posted by juiceclark

Brian and Epo,

Thanks for reminding me of this subject. I stopped by the surf shop on the way home for lunch and he just happened to have a 20 meter kite sail a guy just traded in for a new design...couple hundred bucks out the door. It looks like this but without the hideous graphics:
http://www.kite-line.com/kiteboardin...ils.php?i=1342

If this works out well, we'll try my neighbor's 48' powercat next with this type of deal:
http://www.kit-cats.com/kite/KiteSailPowerboats.htm

The kite you say it is similar to looks like an old style C-kite. These kites have a limited ability to depower through the action of easing the bar. This means you will need to be VERY CAREFUL with how you fly it as you will not be able to instantaneously depower. Instead you will only be able to depower based on where the kite is in the wind window.

I would recommend the use of the newer style bow kite which, through the use of bridles on the leading edge, allows the rider to adjust the angle of attack instantaneously and so effect much more immediate depower. The bow kites are also generally substantially easier to relaunch.

I don't mean to dump on your selected equipment but you should be aware that there are big differences between the various kites out there and some will be far more suitable than others for the task of pulling boats.

Good luck with your experiments but read up on kite safety before you do anything with the 20m kite.

[juiceclark]

Munter,
You are quite correct. These older style kites have been way outdone by the newer technology in bow kites. You can get a bow kite's edge up easily to relaunch, the relevant working area is much larger, etc. That's why you can buy one of these for a couple hundred bucks and the new ones are 10X that amount.

But it doesn't matter anyway. I have a 22,000 pound boat (actually 22,222 with me aboard) and I'm just going to fool around with different ways to run the lines and float her up there. This little kite won't give me 2 knots on a good day. After I get it figured out a bit, I'll consider a 60 meter kite for real.

Epo and Fanie,
Thanks for your concern...should be fine. Kites are just like women...keep them tied down, be careful with your fingers and, mostly, know when to let go!

[brian eiland]

...was doing a bit of research back thru some older subject threads, and ran across this from 2004:

Return of sails in era of expensive oil, enviro. regs?
http://www.boatdesign.net/forums/sho...2836#post32836

...how history repeats itself, and often we don't learn enough from it

[eponodyne]

I note Juiceclark hasn't posted in a couple weeks. I hope he's OK, and an errant kiteline didn't amputate a hand or something.

[juiceclark]

Shoot...I'm so fat that kite didn't have a chance! Everytime I fly that big kite for awhile I become more aware of the fact that a rigid frame kite has nothing to do with flying a kite attached to a boat! It's a lot of fun though...might actually try it on a board or in a kayak sometime soon.

The blow-up/rigid part of my kite makes it very steerable. Being a complete sailkiting novice, I was still able to figure out the idiosycrasies of flying that 20m deal in about 15 minutes. There was a light but constant 7 - 10mph the day I first tried...perfect for gentle learning. It was easy to see that a rigid kite will not fly unless someone is actively flying it! You have to constantly move the bar about and tug and release to get it pulling in the right direction...you have actually fly it.

Had I sewn a big sail out of bedsheets it probably would have worked better than a rigid edged kitesail! So, anyone know of a nice spinnaker for sale?

TC

[kach22i]

http://clicked.msnbc.msn.com/archive/2008/01.aspx

[masalai]

Nice concept, but for yachts the problem is the "controller" as to be effective, the wing must be continuously flown in a sort of "figure 8" pattern & the other issue is the 3 to 500 flexible cable to take the loads and to have a winch that could draw it down under power so the radio control and power supply in the control pod does not get immersed (fall in the water).....