Sailing Directly Upwind

[PAR]

Wouldn't this be easier.

[yipster]

sail and keel have to tack to go directly upwind, in that way i think the machine is cheating
its like telling the police: no i wasnt speeding officer, still houling in my stern (rope with knots)
cant find it now but there was a thread once on 2 connected sailboats zig zagging upwind
otoh when in a monohull you get the keel to paddle, yes, it should move the boat on all points

[Fanie]

To adapt your metaphor, one of the boats is tacking back and forth rapidly while towing the other on a line that is long so the towed boat runs straight.

Yes, you need movement. Don't give up on the idea. We are used to see and do thing two dimentional but with depth. If we can adapt the third dimention (not just depth) (and about time !) then all weird and wonderfull things become possible. The difficult part is to get out of the box.

[ancient kayaker]

Capn Mudd: Gotcha: I'm a tomato man myself ...
Par: that rig will just sail backwards. Nothing to convert the sideways thrust of the sail into forward motion. Isn't that a Balestron rig?
Yipster: for a reach or when running the sailing machine would be locked to the main to allow normal sailing.

[Fanie]

Some of these fancy fishing reels have a level winder on them. It guides the line from side to side when you reel in. How about something similar to that to change the direction (tack) each time it reaches it's end... yes, slightly larger than the reel's

[Chris Ostlind]

While I love the patter, Gents.... The only way this kind of tool is ever going to work is if it is simple to operate (as in any doof can do it) it can make better VMG to windward than the average, bagged-out sail equipped Lido 14 and the excess clutter of having not one, but two boats in the water can be tweaked into something that resembles an ordinary craft.

You guys are on the verge of joining the Doug Lord Club for excess complexity on a sailing craft and that has doom writ large all over it.

Dial it back, keep it clean and to the point and if it works, it will speak for itself. To do otherwise in the face of a shrinking sailing audience is fitfully impudent.

Have you ever seen an Anaconda try to eat a full-sized horse? Didn't think so. That's because the Anaconda has learned to temper his unbridled optimism to the level of his reality.

[MalSmith]

Many years ago, I had a similar idea to the one proposed by Ancient Kayaker, the only difference being that I had the "sailing machine" at the aft end of the boat, i.e. it was a pusher rather than a puller, but fundamentally it was the same. It was just an idea, and I didn't take it any further due to all of the problems, which have been outlined above, and which I failed to find answers for. But it has got me thinking again.

Another possible variation is to have two or more sailing machines that just sail round and round the boat continually, tacking and jybing as necessary. The water fins would have to be controlled by an eccentric linkage to get the trust vectors required. Effectively, what this arrangement would be is a vertical windmill attached directly to a "Voith Schnider" type propulsion system. On downwind courses, the rotating array of sailing machines could be locked and rearranged, all facing forward. With this rotating arrangement, overcoming the heeling moment problems is relatively easy, the sails of the sailing machines can all be canted inward.

If you want to sail dead upwind, then the more "conventional" windmill/propeller system has a lot going for it. However, the sailing machine system is likely to be more efficient for downwind sailing. Note that one way of thinking about a sailing boat is that it is actually a pair of linear propeller blades, one in the air and one in the water.

[TeddyDiver]

Just for the record a "stern sail machine".. these were sold here round 70's.. .

[ancient kayaker]

It's hard to see detail in that pic, Teddy, but it looks like a mast/sail rig attached to the transom. I can't find anything about it Google; do you have more data? I have thought of attaching my Sailing Machine at the stern but I can't figure out a way to make it direction-stable; so raf theat only seems to happen if it's ahead of the center of lateral area to ensure the hull follows the SM.

[TeddyDiver]

I try to find some...
this is the link of the sale announcement the picture was taken http://www.nettivene.com/viewBoat.php?id_boat=329299
In this http://www.huuto.net/fi/showitem.php3?itemid=115478423 magazine was a test of it..
Some VENE magazines also had articles btw 1974-1980
Too old numbers to find online..

[zerogara]

I think only by aplying numbers to your model will you see why wouldn't it work.
You have from the drawing a little boat pulling a big boat, or a small rig attempting to be more efficient than the big rig.
Give us a proposed set of parameters.
Displacement of towed boat
Displacement of s.machine
SA of s.machine
Wind speed
Expected Boat Speed

If all you are trying to do is draw the big boat into a small harbor at 0.5-1kt upwind where it wouldn't have space to steer and tack, yes it may be possible but then again at such a situation I'd still use a dinghy with an outboard to pull on a 50' heavy cruiser and park it on its dock.

With RC controls you can have something like this, again i don't see why.

Much of the efficiency of upwind sailing is related to the small percentage wise component generated of VMG. You are going fast left and right and very slowly forward. Just as a wing glider gives up too much of its energy stored due to altitude to move forward, while sucking up too much energy to move upwards against the wind. Take this small percentage of energy you have very intelligently captured and release in small amounts and devide it by the ratio of the displacement of the sailing machine / combined displacement of boat and s.machine and you are left with a very tiny component of forward moving energy.

A free floating 250k ton tanker can be moved by a single handed Laser up wind? The windage of the tanker alone will draw the tiny little dinghy backwards but if you can isolate the tanker's windage it would have been possible by a tiny little amount that after hours of trying can hardly be measured by a DGPS system.

Originally Posted by ancient kayaker

I have thought of attaching my Sailing Machine at the stern but I can't figure out a way to make it direction-stable; so raf theat only seems to happen if it's ahead of the center of lateral area to ensure the hull follows the SM.

[ancient kayaker]

Zerogara: thanks for your interest, so far I don't see why wouldn't it work; unless I find a good reason I will test it. That will have to wait until I complete the design and build the test unit, and by that time it will be well into Winter here, so Spring (Northern Hemisphere) is the earliest I can report. Design proceeds; at this point the parameters are:

displacement of towed boat: (me + kayak + sailing machine) 275 lb/125 kg
displacement of s.machine: zero (supported entirely by the towed hull)
SA: 20 sq ft/2 m2
mast/sail type: not yet decided
board area: 2 Bruce foils, 2.5 sq ft/0.25 m2 total on a 5 ft/1.5 m beam
wind speed: whatever prevails, usually around 10 to 15k in these parts
expected Boat Speed: off wind 3-4 k: upwind, who knows at this point?

The kayak that will be used for the towed hull is 10 ft/3 m LOA, 2.5 ft/0.75 m beam, molded plastic. It is strictly a displacement mode hull and too beamy to exceed 4k under paddle power. I also have a new canoe nearly finished that may be suitable and should be rather faster.

In a previous test about 5 years ago with a 15 sq ft/1.5m2 sail on the same kayak, it probably beat 4k on a reach or run with a decent wind, not by much but the bow wave reached past the cockpit and soaked my elbows. It often had trouble changing tack and upwind VMG was insignificant, perhaps 0.5k. The major problem with that design was, it was very slow through the turns so it often ended in irons and had to be boxed. It also had awful leeway, but that at least I can imporve with a higher aspect board and more efficient profile, using what I have learned in this forum.

The proposed idea doesn’t appear to have been tried, I have found no record. The object is to demonstrate that it works or determine why it does not. In this test, if it is able to change tack reliably and achieve a useful VMG into the wind I will consider it functional and declare it a success.

It is a bit early in development to speak of efficiency, but if it works the most likely place to look for better performance is the hull shape especially at the bow. Some of the requirements are quite different from a hull carrying its sailing gear onboard in the usual manner. With the sailing machine, consisting of the board, mast and sail, prancing around almost independently of the towed hull and providing front-steering, the hull should be designed for minimum resistance to sideways motion at the bow. That last requirement might be met will something like a garvey or spoon bow. I am assuming here that the sailing machine will pull rather than push the hull as it seems to be the easiest option.

[gonzo]

Ancient Kayaker: Get a pencil and paper and draw the force vectors. That will show you that the force component is downwind. It means you will be going down and not up wind.

[ancient kayaker]

See attached images

[gonzo]

The vector B2 is pointing the wrong direction, it should be in line with the tow and directly downwind. Also, you are not including the torque or the losses by wave action.