Sailing Directly Upwind [Archive]

ancient kayaker

11-01-2009, 08:15 PM

This is an idea I've had for some time, an offshoot of another thread. It's nothing to do with turbine driven propellers.

The process of tacking upwind requires that the boat's heading be changed from the port tack to the starboard tack and so on. The entire boat is rotated including the mast, sail, center board as well as the hull. The rate at which this can be done is determined -and therefore limited- by the boat's turning circle radius and the speed that can be maintained through the change of tack. It is a particular problem for a light, long-hulled slow moving boat such as a sailing canoe in light airs.

So my idea is to separate the hull from the rest of the boat, i.e., mast, sail and vertical hydrofoil (call it the keel, daggerboard, centerboard, whatever). We put all that together as a separate assembly that we call the sailing machine. So long as we prevent it from sinking and keep it more or less upright it will sail in whatever direction we point it, other than directly upwind.

Now we attach the sailing machine back on the hull, but using a vertical axis pivot. The rudder becomes a simple skeg at the stern of the hull. To change tack we simply rotate the entire "sailing machine" to point to the new heading. it will immediately start to sail on the new heading; the hull will follow along behind, adopting the new heading in due course (sorry) under the influence of the skeg.

Such a sailboat need never be in irons, can adjust to wind changes almost instantly and and can sail in a narrower seaway. It would be advantageous with this arrangement for the hull to have minimum lateral resistance, so the hull design drivers are different; perhaps a skimming dish design.

If the sailing machine is connected to the hull by a linkage that permits both rotation and sideways motion while still able to propel the hull forward, then it should be possible to have it zigzag forward while the hull moves in a straight line: directly upwind! To prevent seasickness being induced, the hull may have a small retractable keel to keep it running straight.

I can see some interesting mechanical challenges to be overcome, and it may be limited to small boats, but I don't see any fatal flaw that would prevent it from working.

capt vimes

11-02-2009, 04:21 AM

if the rig and keel/daggerboard/centerboeard/whatever is on the same vertical axis as the sails and points the same direction, the ship will follow this underwater part of your 'sailing-machine' since it makes up for the major part of the lateral plan.... it will not matter which way the hull is pointing... the hull will be draged along....

either this or i did not understand your idea correctly.... ;)

ancient kayaker

11-02-2009, 09:40 AM

alan white

11-02-2009, 09:53 AM

capt vimes

11-02-2009, 10:35 AM

You are correct. With a small skeg at the stern the hull will eventually point along the new course but sail thrust along the new course is established virtually instantly, independently of the direction of the hull.

i do not think that this is going to work...
the sails create a force (forward and sideways) only if kept in the wind... therefore you need to control the sails and their angle...
this is done by having the sheets fastened on the winches... with a hull rotating freely around the mast you will not be able to control the angle of attack of the wind on the sails... you need some force to counteract the sideways forces on the sails otherwise they will just bail out...

ancient kayaker

11-02-2009, 10:39 AM

What about heel? The sailing rig wants to heel quickly once tacked while the hull is at right angles to the new course. As soon as the sail fills, the rig wants to sail forward, but that would be at right angles to the hull. The question is whether that force is easily counteracted by the sailer's weight.
Also, I can see the drag component causing the hull to go backwards, the force lifting the bow and sinking the stern (maybe not a bad thing to get the bow around quickly).
As far as practicality goes, no comment, since I don't believe you are trying to invent anything practical, but just noodling with new ideas, which is always healthy.

I don’t think the heeling is much different from any other sailboat; heeling forces will be countered by the hull’s righting moment. The rig is mounted on the hull by a linkage that permits only sideways motion and rotation about a vertical axis. Heeling forces will be transmitted from the sailing machine to the hull through the linkage. It will have to be robust, but no more than a rotating mast.

As the sail fills on the new course the rig will want to sail in that direction and the front of the hull is going to be dragged sideways. Much the same as happens to the stern of a conventional sailboat due to rudder force, but it will happen much faster; the regular shape of stem is not going to work well here.

I didn’t understand your point about the drag coefficient making the hull go backwards.

As far as practicality goes, I plan to try this out; the plan is to install it on a cruising kayak or canoe: rather than a purpose-designed one. That may compromise the performance but it should identify the challenges better than noodling. Hopefully it will not have an adverse effect on my health!

TeddyDiver

11-02-2009, 11:30 AM

How about installing that sailing machine, instead of a canoe, to a "non directional" hull. By this I mean either a rigid hull without bow and stern or a hull with variable form.. :D

ancient kayaker

11-02-2009, 04:06 PM

How about installing that sailing machine, instead of a canoe, to a "non directional" hull. By this I mean either a rigid hull without bow and stern or a hull with variable form.. :D

-do you mean a coracle?

gonzo

11-02-2009, 04:17 PM

The wind will be on the same side of the sail. You are not sailing straight upwind but are on a tack. If you turn the hull or "the sailing machine" as you call it at 90 degrees to the course, the boat will stall. You will never sail straight upwind. This is nonsense.

yipster

11-02-2009, 04:58 PM

may i ask for a simple 1000 words picture telling the forces

ancient kayaker

11-02-2009, 06:20 PM

Think of the sailing machine as a separate sailboat towing the hull, but the sailing machine does not have its own hull because it is suported by the linkage. The linkage attaches the sailing machine to the hull and permits it to rotate (mast and keel rotate together) and move sideways with respect to the hull. The sailing machine tacks upwind, zigzagging in the usual way, but the hull moves in a straight line.

In the figure, to keep it simple I have not shown sheets or steering provision for the sailing machine, but it will obviously need them.

Note: there is a mistake in this picture: in figure F) the sails should be shown to port

Hunter25

11-02-2009, 06:59 PM

I remember an idea like this years back. I think it was on a cat hull, but could be wrong. The jib and main shared a common boom that rotated with the mast. The jib would weather vane out to leeward, while the main would cock up to windward. The hull could sail directly up wind, or nearly directly up wind with the sails set for a more ideal angle of attack. Leeway is an issue on this point of sail and it would not be a point of sail used much, but possible. The hull could be steered around, while the sails remained in an ideal angle to the apparent wind.

zerogara

11-02-2009, 07:13 PM

Like you said a sailing machine (sailboat) and a tug heading steady up wind. The sailboat is tacking upwind like a normal sailboat does and drags a tug boat.
Question, are you on the tug or on the sailboat? How big (displ.) is the one and how big is the other. Why would you want to use a sailboat instead of a diesel? What would you be rather be doing, sailing or motor boating?
The freight/tug you are drawing can be probably be carried on an appropriate sized sailboat just tacking up wind to get to its destination faster than this system of those two boats.

alan white

11-02-2009, 08:49 PM

I don’t think the heeling is much different from any other sailboat; heeling forces will be countered by the hull’s righting moment. The rig is mounted on the hull by a linkage that permits only sideways motion and rotation about a vertical axis. Heeling forces will be transmitted from the sailing machine to the hull through the linkage. It will have to be robust, but no more than a rotating mast.

As the sail fills on the new course the rig will want to sail in that direction and the front of the hull is going to be dragged sideways. Much the same as happens to the stern of a conventional sailboat due to rudder force, but it will happen much faster; the regular shape of stem is not going to work well here.

I didn’t understand your point about the drag coefficient making the hull go backwards.

As far as practicality goes, I plan to try this out; the plan is to install it on a cruising kayak or canoe: rather than a purpose-designed one. That may compromise the performance but it should identify the challenges better than noodling. Hopefully it will not have an adverse effect on my health!

Honestly, it's hard to imagine what's going to happen, though when I first "saw" it, it appeared that the tacking of the sail rig would encounter leeway, causing the hull to go backwards and therefore not come around, at least not for a critical moment.
But I may not be seeing it clearly.

ancient kayaker

11-02-2009, 11:38 PM

I remember an idea like this years back. I think it was on a cat hull, but could be wrong ... .
-it would be great if you could find out more about it. Were you thinking of the Flip-tacker by any chance? That's a different concept, see http://www.boatdesign.net/forums/sailboats/highly-assymetrical-wing-sail-25362-2.html. I was thinking a cat hull might be good for this concept, with the rig tacking between the amas, instead of ahead of a monohull as I sketched it. I was also thinking a garvey style hull might work.

... Question, are you on the tug or on the sailboat? How big (displ.) is the one and how big is the other. Why would you want to use a sailboat instead of a diesel? What would you be rather be doing, sailing or motor boating?
The freight/tug you are drawing can be probably be carried on an appropriate sized sailboat just tacking up wind to get to its destination faster than this system of those two boats.
- I assumed the crew would be on the hull being towed as I think this idea is best suited for small craft. Why would anyone want a stinky diesel when they could be sailing? I think this idea has the potential to outperform a conventional rig upwind, although it may be handicapped on other points of sail.

Honestly, it's hard to imagine what's going to happen, though when I first "saw" it, it appeared that the tacking of the sail rig would encounter leeway, causing the hull to go backwards and therefore not come around, at least not for a critical moment.
But I may not be seeing it clearly.
-yeah, there are bound to be some interesting learning experiences with anything this far from normal. I think steering and sail control will be the main challenges.

TeddyDiver

11-02-2009, 11:39 PM

-do you mean a coracle?

That's one possibility.. another is to have a squeezible coracle.. sailing machine could be attached in the midship. Somekind of "flutter" like action changes the sailmachines tack while it pivots from side to side.. like a bird flying with one wing :)

yipster

11-03-2009, 06:30 AM

sail, keel(s/hull/tow) locations are variable i understand ? would it not be constantly tacking barely giving the parts time to setle
interesting thought and thanks for the pic, drawing some complex arrows here but dont dare an opinion yet

ancient kayaker

11-03-2009, 08:38 AM

The idea is really aimed at a slow moving and slow turning boats. Fast nimble ones don't really need it most of the time.

Upwind it could be sailed like any other sailboat on long tacks, but the ability to perform short tacks would be valuable in confined waters without an engine. Might avoid losing gelcoat or paint wiggling into a marina spot, or working along a narrow river.

There is an outside possibility it would be faster upwind since it would lose no speed changing tack, and the ability to sail a different course from everything else in a race might make a big difference around the buoys. I wonder what effect it would have on the port tack rule? A boat with 2 such sailing machines on one hull would be interesting too, could have one on each tack ...

Mostly it's just an idea that I think might work, therefore I naturally want to try it. But it might have already been done or have a fatal flaw I didn't see, so I thought I'd bounce it off you guys - that's one of the most valuable things about a forum.

Chris Ostlind

11-03-2009, 12:11 PM

Terry,

Other than this is a fun, outside the loop, approach to your stated interest, I do not see it working in the real world. I admire that you plan to actually build an example of the concept to provide a proof of its potential, but until that happens, this is going to remain a mental exercise.

For hundreds of years some of the brightest practical, as well as theoretical, minds in the boating trades have danced with this idea, or ones very much like it, to very unsatisfactory results.

The structural issues of the engine, itself, as well as the attachment process to a suitably buoyant hull that can accept a cantilevered device and remain on its designed lines, will be more than an accomplishment.

On another note, I simply must take exception to this quote from your first post... "It is a particular problem for a light, long-hulled slow moving boat such as a sailing canoe in light airs." I have not experienced this phenomenon, as you describe it, with any of my sailing canoes, number into the mid teens at this point in my design and build experience.

The issues you describe are present, potentially, for all sailing craft in light airs and not specific to sailing canoes. In fact, light boats have the potential to move fast enough in the smallest of puffs that the attached flow over the keel form allows responsive turning from the helm far better than a heavier boat, which requires a more sustained flow of air over the sails in order to generate the necessary motive power.

In any event, I encourage you to explore your idea and I look forward to the solutions necessary to fixture the engine to the craft in order for it to work as designed.

ancient kayaker

11-03-2009, 02:04 PM

Even though I'm its parent I have to agree with your comments on this idea. I would still like to read about any precedents, if there are refences on the net.

The "sailng canoes" I referred to were canoes (and kayaks) not initially designed for sailing, with small rudders, sail areas and no hiking out, so they were relatively slow moving and have huge turning circles. Also some of my earliest ventures into sailing and designing my own gear: I didn't know about pivoting the boat close to the CoG for example.

A properly designed sailng canoe carrying a respectable sail area (and competent skipper) should, as you noted, not have the same problems, and no slight was intended.

Nonetheless, Gonzo for once is wrong: there is no theoretical reason why it shouldn't work. Aircraft, multihulls and cleanliness in hospitals all had the same reception. Hopefully I can get it done and let you guys know how good or bad it is ... I have started working on the detail design - or more accurately am refining the conceptual design.

Chris Ostlind

11-03-2009, 02:45 PM

... Aircraft, multihulls and cleanliness in hospitals all had the same reception.

LOL... it's always nice to pick the stuff that has gone on to some degree of success. Would you also care to suggest the many, many thousands of "great ideas" that never moved beyond the blank sheet of paper... you know, just to keep it all in balance? ;-)

It's kinda like the folks who say they have sensations of having lived past lives. They always seem to have been a Prince, or a Captain of a bitchin, powerful ship of the sea... but never a toothless pauper, or a victim of the Black Death.

Hopefully I can get it done and let you guys know how good or bad it is ... I have started working on the detail design - or more accurately am refining the conceptual design.

As said before, Good Luck in your exploration, but to liken this to the many thousands of years old multihull genre is still kinda on the cheeky side of the equation, no?

Sooner, or later, every dreamer has to suck on the tangy egg of reality if they expect to make the leap from, "WOW! how cool!" to actually experiencing it as a functioning product. If you are one of those tiny numbers of people who can dream it and it soon slays the world, my hat is off to you. If, however, you are like the rest of us, then only hard work, many failures and the gift of grace as you absorb your humanity, will get you to the goal line... if there is, in fact, a tangible goal line for the dream.

Fanie

11-03-2009, 04:01 PM

If you have two sail boats tacked to either side of the wind, and they are tied with a line, will they head directly upwind or will they both go in irons ? Assume they both maintain their angle to wind.

If they are heading directly up wind - then you can sail directly upwind. If they both go in irons - you cannot sail directly upwind.

gonzo

11-03-2009, 06:28 PM

They will stall and weathercock.

Fanie

11-03-2009, 06:53 PM

That is correct. That is why you canot sail directly upwind. You can get close though. The closest to wind a plane blade can fly is what... 15 deg, cannot remember. Same will apply on a boat if you have a full wing like a solid sail, but a boat sail is only half a blade.

If the above was true you'd be able to sail with two sails side by side and just trim them to either way of the wind and you'd sail directly to wind. I checked that already some time ago...

alan white

11-03-2009, 07:17 PM

I think I understand that the rig described doesn't sail directly upwind, but can short-tack so well that VMG is improved. While I can't how this would be accomplished, neither do I see that anyone else understands why the rig shouldn't work.
Boat speed, at least that of most normal (i.e., small non-racing) boats, is always comprimised during a tack. If it could be possible to significantly speed up the re-setting of the sails to opposite tack and then use that early thrust to carry the boat's hull through efficiantly, it might be possible to increase upwind speed of a given example.
I for one encourage experimenting in this area, if only because no matter how fruitless the end result might turn out to be, there is always the remote possiblity that something useful can be learned.
It's how things get improved. At a small scale, that of kayaks and very light boats, experimenting is low-cost fun. It's just one small step beyond building a model, or even designing itself.
I say, go for it, Terry, until you meet with failure, or better still, success.

ancient kayaker

11-03-2009, 09:57 PM

LOL... it's always nice to pick the stuff that has gone on to some degree of success. Would you also care to suggest the many, many thousands of "great ideas" that never moved beyond the blank sheet of paper....
-Chris, I’m far too positive to quote failures, but I intend to suck the lemon of reality on this one. In Tom Lehrer's immortal words "soon we’ll be sliding down the razor blade of life"

If you have two sail boats tacked to either side of the wind, and they are tied with a line ...

-the line will break! Fanie, that isn’t what is (hopefully) going to happen here. 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.

Alan: welcome to the thin ranks of the Maybe’s. At this stage of course, anyone who is totally convinced it will work is probably certifiably insane. I too am from Missouri on this one but it’s worth trying. Thanks for the good wishes!

Capn Mud

11-03-2009, 10:56 PM

Terry,

I doubt I have a right to comment on this forum....... BUT

To me it would seem that going back to the question of the practicality of heel and providing righting moment will be a major issue for you to solve in your design and I cant really see how it will be done (hence my comment that perhaps I have no right to comment - probably not imaginitive enough - and if masters like Chris Ostlind didnt mention it....)

Anyway - from what I can see some how you have:
1. A connection between the sailing machine and the main hull that is pinned in the horizontal plane.
2. A sailing machine that has minimal hull of its own and righting moment only from its skeg - it will want to heel hard and look to point up to windward.
3. It then tacks and fills on the other tack? And so on with very short boards and lots of tacks.

My queries:
1. Can you get enough speed from the very short boards before it points up and fills.
2. Can the horizontally pinned connection be made stiff enough to pass the heeling moment though to the main hull without bending / breaking (given the number of cycles of loading one way then the other if it can be strong enough fatigue would become an issue)
3. Given that this is pinned in the horizontal direction when it starts to heel will the whole assembly be "stiff" enough (in a sailing sense) that the whole thing doesn't just hinge in on itself?
4. Can the connection beam to the sailing machine be strong enough to transmit these heeling loads in torsion.
4. If all of the above do work OK does the passenger have to keep changing sides to hike out every time it tacks - could be quite busy given the short boards?

I really like the concept but am struggling with envisaging it actually working in practice - hopefully you prove me wrong.

Cheers,
Andrew

Chris Ostlind

11-03-2009, 11:23 PM

... In Tom Lehrer's immortal words "soon we’ll be sliding down the razor blade of life"

Or, perhaps, you'll be Poisoning Pigeons in the Park?

ancient kayaker

11-04-2009, 12:49 AM

... you have:
1. A connection between the sailing machine and the main hull that is pinned in the horizontal plane.
2. A sailing machine that has minimal hull of its own and righting moment only from its skeg - it will want to heel hard and look to point up to windward.
3. It then tacks and fills on the other tack? And so on with very short boards and lots of tacks.

My queries:
1. Can you get enough speed from the very short boards before it points up and fills.
2. Can the horizontally pinned connection be made stiff enough to pass the heeling moment though to the main hull without bending / breaking (given the number of cycles of loading one way then the other if it can be strong enough fatigue would become an issue)
3. Given that this is pinned in the horizontal direction when it starts to heel will the whole assembly be "stiff" enough (in a sailing sense) that the whole thing doesn't just hinge in on itself?
4. Can the connection beam to the sailing machine be strong enough to transmit these heeling loads in torsion.
4. If all of the above do work OK does the passenger have to keep changing sides to hike out every time it tacks - could be quite busy given the short boards?
...

{abbreviations: HM heeling moment; RM righting moment; SM sailng machine}

Your summary is correct except that the connection between the SM and the main hull will be pinned in the vertical axis. The pointing direction of the SM is controlled through the connection.

Speed through the frequent tacks is sustained by the momentum of the hull. The time required to change tack is very short which makes the short boards practical, since the boat loses virtually no speed through the tack. The SM is pushed along by the main hull during a tack change, but the SM is much the lighter of the two components and the time is brief compared with the time on each tack.

The strength and stiffness of the hull-to-SM connection is a design challenge. It's not an easy one, it has to do a lot and it has not yet been addressed. It’s a work in progress and I think it can be done, but at this time I an concentrating on the overall configuration. I have glanced at the requirements for the connection, which I call a linkage; the critical one seems to be that the angle between the link and the SM must not reach 90 deg, which would cause a mathematical singularity that would likely be resolved by breakage.

I have been trying to predict the behavior of such a craft: I have determined that, if a conventional sail and keel SM is used there will be a significant HM transmitted to the main hull which will reverse at each tack. This will happen fast enough that it may set up resonant heeling in the main hull leading to a death roll. It is not practical to control this with ballast under the SM that would then have to be supported through the SM-hull connection, nor by moving ballast or crew on the main hull, as it will happen too quickly. Therefore one of the following is needed:
1) Bruce foils on the SM instead of a vertical keel to eliminate HM at source
2) amas on the SM to react the HM within the SM
3) the main hull will react the HM, i.e., it is a catamaran

For the first experimental model, assuming I can get the design that far, I plan to use 1)

Capn Mud

11-04-2009, 03:02 AM

Your summary is correct except that the connection between the SM and the main hull will be pinned in the vertical axis. The pointing direction of the SM is controlled through the connection.

Horizontal plane - Vertical axis. Potayto - Potarto, 6 of one - half dozen of the other

PAR

11-04-2009, 03:04 AM

Wouldn't this be easier.

yipster

11-04-2009, 07:38 AM

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

11-04-2009, 08:50 AM

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

11-04-2009, 09:38 AM

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

11-04-2009, 10:17 AM

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 :D

Chris Ostlind

11-04-2009, 10:30 AM

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

11-04-2009, 11:22 AM

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

11-04-2009, 12:16 PM

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

ancient kayaker

11-04-2009, 04:16 PM

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

11-05-2009, 07:09 AM

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

11-05-2009, 07:34 AM

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.

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

11-05-2009, 10:50 AM

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

11-05-2009, 02:08 PM

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

11-05-2009, 03:34 PM

See attached images

gonzo

11-05-2009, 03:42 PM

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.

ancient kayaker

11-05-2009, 05:15 PM

Gonzo, the external forces acting on the sailing machine (SM) are the wind and the resistance of the towed hull which are in the same direction. Both have components pushing the SM to its port (45 deg left of upwards in the figure) which are opposed by the hydrodynamic forces B1 and B2 on the daggerboard as shown.

I have drawn the SM with a hull of its own but it is purely as an aid to understanding. However, if you look at it in that manner and replace the red beam with a towrope, you have a towing boat on the startboard tack pulling the towed boat to windward.

All that has to be done to see my idea in action is to replace the rope with a stiff beam pivotted at both ends, delete the towing boat's hull and let the beam support the rig and board.

There is torque on the red beam due to the driving force of the sail and the drag of the daggerboard, but it is static and results from the forces shown not being coplanar. The torque is passed to the towed hull which will heel to port in response.

I haven't looked at the effect of wave action; this is a simplified diagram.

gonzo

11-05-2009, 05:41 PM

You are not correct. There isn't a single vector of force pointing downwind. All of them are somehow pointing in the direction that helps make your dream work. If you had ever towed a boat, you would know that the tug tries to line up with the tow. You don't have the torque or the pull (backwards and not forward as you show it) from the tow.

Rick Willoughby

11-05-2009, 09:18 PM

See attached images

Terry
The lift force on a foil is perpendicular to the direction of the wind and the drag is in line with the wind. This means the vector angle of the resultant force on the foil can never be forward into the direction of the wind.

Stating this another way, the direction of lift is not related to the orientation of the foil. It is related to the direction of the wind.

Putting this in terms of your diagram the "Drive" force will always be negative.

To get positive drive you have to bear away off the wind until the angle of the resultant force on the sail has a component that is positive in terms of moving the boat forward.

Taking the sail off the hull does not achieve much. You might be able to tack the whole sailing machine faster than a boat but you still have to pull the boat around to sail on the opposite tack. The boat cannot sustain motion directly into the wind.

Rick W

Tcubed

11-05-2009, 10:16 PM

This reminds me of http://www.boatdesign.net/forums/boat-design/flutterby-drive-24631.html

ancient kayaker

11-05-2009, 11:07 PM

Tcubed first: that's the original, there's even a post of mine on that thread. I subconsciously regurgitated the idea, Oops! My apologies to Grover if he is reading: I wonder what happend to that idea which was stern mounted.

Gonzo: my vector diagram was confusing because the wind-derived forces (D-S-B1) are shown acting on the sailing machine (SM) whereas the towing force and its components (TDB2) are shown as they act on the towing beam not the SM. I have added a new vector diagram which shows all the forces that act on the SM; the revised figure is colored and the new diagram is in green. Hope it helps. Please note the board forces are normal to the board, the sail forces are (approximately) normal to the sail, and there are 2 opposite forces of magnitude T acting on the beam.

Rick: quite true: but the SM IS bearing away from the wind. I added arrows on the hull and SM to show their directions. I added tracks for the hull and SM; I hope the figure is not getting too cluttered.

To reiterate; taking the sail off the hull achieves one thing only, the SM can tack very quickly, because the torque that rotates it is applied from the much heavier hull: the SM has no rudder. Also hull speed is not lost through the tack. The direction of the towed force is oscillating too rapidly for the hull to follow it; the hull follows the averaged-out force which is windward; refer to the track diagram.

Rick Willoughby

11-05-2009, 11:34 PM

Terry
You are correct. The resultant sail force is behind perpendicular so it will do as you say.

Basically it is oscillating air and water foils in combination. It is the simplest form of the propeller/turbine configuration. You need to set up some form of flip system to get it to oscillate back and forth automatically.

A better set up would be two sailing machines working on opposite tacks so the yawing of the hull is eliminated. This was a big advantage over the Hobie flapper drive over my single oscillating foil. I had high imbalance pitching forces whereas the flappers have high but balanced yawing forces - the pitch force is much lower and not balanced.

A few systems like you have were offered on the DDWFTTW thread.

The advantage of this system over a propeller/turbine is that you are not converting through a mechanical drive train. You are only reacting forces.

Rick W.

gonzo

11-06-2009, 01:30 PM

The vectors are still wrong. There is no vector for the negative force of the towed hull or the torque produced on the "sailing machine" as it pulls backwards from its aft end.

ancient kayaker

11-06-2009, 06:32 PM

The vector "T" in the green diagram represents the hull drag: if you are enquiring about torque on the sailing machine (SM) around the vertical axis, it is virtually zero because the beam is pinned to the SM at its balance point for this point of sail; that will probably be further forward than I have shown. Torque is applied to the SM for tacking/steering purposes of course, which will cancel torque caused by beam tension while holding a tack.

On other points of sail the beam pins will need to be locked, I expect, but that will become clearer during testing. Assuming it sails at all, that is. I think you and others are right to be sceptical, I am still looking for the fatal flaw myself, but I haven't found it so far.

Keep looking! If it is hopeless I don't mind admitting it and it will save a lot of bother building and testing it. I haven't started cutting wood yet but I sorted through the stack and I have what I need. I'll have to buy some Al tubing, a couple of pivot bearings and a tarp for the sail, looks like I have the rest.

gonzo

11-06-2009, 07:17 PM

There is one T forward and one T backwards. If the forces are applied like you say, the tow would have to move sideways. The torque on the "sailing machine" will make it weathercock. Try towing something and then you'll see.

ancient kayaker

11-06-2009, 09:35 PM

Acting on the beam are 2 force vectors of magnitude T, both along its axis, so it will not move sideways. As the sailing machine zigzags the tow will follow it but in an attenuated zigzag as shown in the figure.

You have a point with the weathercocking. If you had a towing line that is angled off the centerline of a tug it will be pulled off course in one direction or other, that will depend on where the tow rope is secured to it. Too far aft and it will weathercock, usually the case I imagine, too far forward and it could end up helplessly sailing around the tow. I will take that into account in the design; I may have to experiment to find the best position.

Rick Willoughby

11-07-2009, 12:30 AM

Terry
Before you start cutting you should sit down and work out how quickly it needs to tack to make way at a reasonable speed and without having a ridiculously long towing rod.

Take it a step further with a catamaran and water/air oscillating pair on each hull synchronised to work in opposing tacks. The air foil needs to be arranged so it has mechanical advantage over the water foil.

Rick W

ancient kayaker

11-07-2009, 02:02 AM

One thing that cannot be allowed is to have the SM to become normal to the beam as it's speed would have to be infinite to keep up with hull movement. Most sail boats are comfortable tacking through 90 degrees so I will use that for my calculations. The beam, therefore must move over an included angle of less than 90 degrees; I will choose 60 degrees arbitrarily at this time. It seems sensible to have the lengths of each tack significantly longer than the length of the turns, so the turn arc length becomes the driver for beam length. That must be an informed guess as no data is available for this configuration.

I think the boat available for the test is unlikely to exceed 1 k VMG so using the assumptions and calculation in the figure I get beam length of 5.6 ft, minimum. For now I will let it be 6 ft and see how the design looks. The target VMG of 1 k is hardly ambitious but per post #42 it represents at least 100% improvement for the boat that will be used.

The catamaran concept is likely to outperform it and of course a bigger boat would also have merit but for a demo that is not needed and beyond my resources!

gonzo

11-07-2009, 12:07 PM

I think the numbers are just a fantasy. You are inventing them to "prove" a theory. If you have a towed boat attached to a rigid arm, the towing vessel will move in an arc. Also, if you look at your drawing, even though the "sailing machine" is pulling at different angles from the direction of assumed movement, the tow magically goes in a straight line. You don't need to build any fancy machine to try the concept. Tie a bucket to a sailboat and it will show you what happens.

Chris Ostlind

11-07-2009, 12:52 PM

Just curious, Terry, but what is the reasoning behind the suggestion of tacking through 60 degrees?

ancient kayaker

11-07-2009, 06:00 PM

Just curious, Terry, but what is the reasoning behind the suggestion of tacking through 60 degrees?

Chris: the sailing machine tacks through 90 deg, as is typical. It must never be at right angle to the beam or it will be pushed sideways, so the beam must rotate less than 180-90 deg range; the 60 deg limit (+/- 30) I chose seems a reasonable place to start. A larger range of motion for the beam would force me to reduce the tacking angle.

Gonzo: I guessed the time needed for the sailing machine to change tack. It is much less than any sailboat I have ever seen. The torque to achieve that is derived through a harness and reacted by the hull's weight, instead of a rudder. That is the central principle, without it all fails.

Chris Ostlind

11-07-2009, 06:08 PM

Well, it looks to me like the talking part is all done. What's left is the building of said item and showing a video as to how it does, or does not work.

I await the link to Youtube.

ancient kayaker

11-07-2009, 06:19 PM

Yep! I'll work on my video skills; the last I shot a video the camera was shoulder-mounted so I may have some catching up to do!

Chris Ostlind

11-07-2009, 06:27 PM

If I'm in the area when you look to do this, I'll be happy to shoot it for you. A close friend who is a canoe designer lives in Grand Bend and I'm looking to visit him anytime after the water starts moving again.

So, keep us posted.

Rick Willoughby

11-07-2009, 07:37 PM

Dave Gudeman

11-07-2009, 11:00 PM

This looks like a fun project. I'm trying to visualize how it works and think I have a mostly equivalent mechanism that is easier to understand. Would you say that this is pretty much the same as what you are suggesting except for the arc of the motion of the SM?

Imagine a rudder mounted at the front of a catamaran in such a way that it can slide back and forth from port to starboard (it's not used like a rudder, but this is the easiest way to explain it...). Start with the rudder all the way to starboard and turn it so that it would turn the boat to port if the boat were moving. Now, keeping the rudder from turning, whip it across the rails to the other side. It will move the boat forward. Now turn the rudder the other way and whip it back. It will move the boat forward again. That's the propeller of the system.

Now vertically mount a wing above the propeller to act as a turbine. They are mounted in such a way that when one of the foils is pointed directly forward, they both are. There is a geared rotation so that one one rotates so does the other, but not necessarily by the same angle. There is also some sort of mechanical linkage at each end of the rail such that:

(1) when the rudder/wing combination hits the starboard end of the rail, both foils are turned to port.

(2) when the rudder/wing combination hits the port end of the rail, both foils are turned to starboard.

Face the boat directly into a head wind and push the device against the starboard rail. The foils turn to port. Now the wind drives the wing, pushing it to port. The rudder is also driven to port and drives the boat forward. When the contraption hits the port end of the rail, they turn and reverse direction.

No matter which direction the foils are moving, the boat is driven forward. You can think of this combination of foils as a sailboat-without-the-hull that is tacking back and forth.

ancient kayaker

11-08-2009, 10:41 AM

Chris: it would be great to meet at last: one caveat though, I'm in Alliston -about an hour north of Toronto -which is about a 12 hour drive if the roads are good. If you are passing through Toronto I can easily collect you and provide accommodation. I this one near the top of my priority list and I plan to be ready for the Spring. Is your friend Skip Izon by any chance? I recently read of his "Little Tripper" which is the same kind of boat as my Dora which is in the $100 boat challenge thread (his boats cost a bit more).

Rick: agreed, 1 k (knot) is pedestrian but represents about 100% improvement on the best VMG that boat has done under sail using a sail of similar size. In a tiny kayak with a small sail and the drag from the paddler it is hard to do better. The sail is self-tacking.

Dave: yes, that's the same principle. Your description is close to what I understand Rick was suggesting. Your rudder is acting like a fish tail or a yuloh, but at the bow instead of stern. We kayakers do that sideways when we need to get closer to the dock! The automatic rotation at the end of each "mini-tack" is something I think I can rig, once I see the thing on the water. Is this a concept or actual hardware?

Chris Ostlind

11-08-2009, 12:17 PM

Chris: it would be great to meet at last: one caveat though, I'm in Alliston -about an hour north of Toronto -which is about a 12 hour drive if the roads are good. If you are passing through Toronto I can easily collect you and provide accommodation.... Is your friend Skip Izon by any chance? I recently read of his "Little Tripper" which is the same kind of boat as my Dora which is in the $100 boat challenge thread (his boats cost a bit more).

Yep, Skipper is a long time designer buddy and I've been wanting to go out sailing with him for a very long time. Skip has a strong interest in sailing multihulls and I'll probably bring one of my boats along so that we can just simply get out on the water and sail.

Another canoe friend, John Hupfield, lives up by Parry Sound where he owns Lost in the Woods Boatworks. He runs a great, sailing canoe get together every year at Killbear Provincial Park and usually attracts some very interesting folks twith whom you'd probably enjoy hanging out.

Let's see what shakes out as you move along your path of discovery.

Dave Gudeman

11-08-2009, 12:52 PM

It's just a concept. I was having trouble visualizing how your idea is going to work so I tried to come up with something that eliminated the conceptual baggage of the towing and tacking. I'm not suggesting that my scheme would work better, but for me it is easier to understand.

As to your scheme, I confess that still can't see how it is going to work. You have been ambiguous over whether you have a hull on the SM. Without hull I can't see how you handle the forces and with the hull I can't see how you tack quickly enough.

I'd love to see some more details.

ancient kayaker

11-08-2009, 01:09 PM

Chris: a few years ago I admired a lovely wooden sailng canoe at either Midland or Penetang, can't recall which. perhaps it was John's .

Dave: no ambiguity about it: the SM has no hull and is entirely supported by the beam attaching it to the towed hull. In an earlier post or two I used an analogy of a small boat towing a larger one to illustrate the operating principle in response to questions; sorry if that caused some confusion.

I have all the wood and half the Ally on hand and I'm off with my shopping list shortly. Before that I have to finish a boat or two and move them out of the workshop to make room for the work; before that I have to clean out the gutters so the boats don't interfere with the ladder; before that I have to take down the gazebo which is in the way and lower the pool level and fix a fence and ... sigh!

gonzo

11-08-2009, 04:18 PM

However, you don't take into account any of the torques, vertical and horizontal produced by the setup. Also, you come up with figures that are imaginary. The angles of tack and length of force vectors are made up to "prove" your theory. Nothing in all the data available on physics supports your claims. The argument that inventions in the past were met with resistance is not proof. The Wright brothers, for example, did not make wild claims but just built a flying machine. Deeds not words!

Rick Willoughby

11-08-2009, 04:23 PM

....

Rick: agreed, 1 k (knot) is pedestrian but represents about 100% improvement on the best VMG that boat has done under sail using a sail of similar size. In a tiny kayak with a small sail and the drag from the paddler it is hard to do better. The sail is self-tacking.

...?

Terry
Where did the 1k = 1.15fps come from?

Rick

Rick Willoughby

11-08-2009, 04:35 PM

ancient kayaker

11-08-2009, 05:47 PM

Terry
Where did the 1k = 1.15fps come from?

Rick

Rick: Oops, that's for mph. Should be 1.688. Min beam length is now 8 ft

Concerning the oscillation; it is more severe in the video than it should be for the sailing machine design. It is caused by the torque needed to move the blade sideways with the beam. The following is non-rigourous.
T = F.L
where F = force on blade, T = torque, L = beam length
Driving force ignoring friction = D = F if it is set at 45 deg

For the sailing machine assuming the same driving force:

sideways force on bow of towed hull = F.sin(A) where A = max angle between beam and centerline of hull
and torque on hull is H.F.sin(A)
where H = bow distance from center of lateral area or about half the hull length

The average torque is the integral of the torque over the range of the beam angle which is F.L for the paddle and 0.5H.F.sin(A) for the SM. Assuming in both cases the beam oscillates sinusoidally from +30 to -30 deg those values become F.L and 0.25 x H.F
Using my dimensions of L = 8 and H = 5 gives us values of 8F and 2.5F. I believe in practice the SM oscillating torque will be lower still, since the paddler must overcome blade drag by additional torque through the beam whereas drag is overcome within the SM system before any force reaches the beam. We will have to wait to see if that is correct.

bistros

11-09-2009, 10:33 AM

Yep, Skipper is a long time designer buddy and I've been wanting to go out sailing with him for a very long time. Skip has a strong interest in sailing multihulls and I'll probably bring one of my boats along so that we can just simply get out on the water and sail.

Another canoe friend, John Hupfield, lives up by Parry Sound where he owns Lost in the Woods Boatworks. He runs a great, sailing canoe get together every year at Killbear Provincial Park and usually attracts some very interesting folks twith whom you'd probably enjoy hanging out.

Let's see what shakes out as you move along your path of discovery.

If you guys do plan to get together in 2010, let me know - it is an easy six hour drive from here to Alliston and I'd come in a heartbeat. I spent a lot of my misspent youth camping in the Pinery Provincial Park in Grand Bend. Lots of great memories from the Bend.

Tricky little harbor there on the river that has a tight choke point on the jetty/entrance to the lake. Lots of beer dispensing locations and good breeze regularly.

--
Bill in Ottawa

Dave Gudeman

11-09-2009, 01:11 PM

Kayaker, it sounds like you are designing something similar to what I described except that it will move on an arm instead of on a slider? So why didn't you say so :) . It's interesting that we have opposite ideas of what makes it easy to understand.

One thing I that occurred to me in the slider design is that the wing is always on a beam reach when going upwind and it is getting the benefit of faster apparent wind so it is actually producing its peak output going upwind (whether this applies to the mechanism as a whole, I don't know). It seems that your system would be the same, right?

Rick, I'm surprised that you think this might do better than a turbiprop. You have said in other threads that long and thin foils are more efficient, but wouldn't this mechanism require a broad foil to generate enough power?

But it would be interesting if it could be made efficient. Suppose you do a two-wing system as you suggest. When the boat is going upwind, you would have the mechanisms to produce power directly upwind and the wings would be effectively on a beam reach. When the boat is on a reach, you fix the wings in place and use them like regular sails. When going directly downwind, you reverse the system like in the DDWFTTW thread. Given the versatility, I wonder if this system might not be optimal in all headings.

ancient kayaker

11-09-2009, 03:05 PM

Bill: finally I will meet someone who drives as slowly as I do. Beer I can manage, not much sailing in Alliston but Barrie and Lake Simcoe are only a half-hour away if we can find a suitable boat. Or I can host a small army with kayaks and canoes ... :cool:

Geez Dave, where were you at the start of all this when I was trying to figure out how to do it? You could have saved us a whole week of analysis, argument, and passion that could have been put to better use :)

I doubt my little boat will have enough speed to generate significant apparent wind. I could experiment with a bean diet I suppose :eek:

Mostly I just want to see if it works and produce a workable alternative to floating windmills. I'm also interested to know how such a rig will behave on other points of sail. Once I've done that the torch must pass from my failing grasp ... :) :)

Dave Gudeman

11-09-2009, 09:21 PM

I just realized that my speculation about optimal efficiency was nonsense. What I was thinking is that this device doesn't have the inefficiencies of sails on high and low points of sail, and it doesn't have the inefficiencies of rotating foils. But it obviously has its own inefficiencies in the pauses at each end.

Kayaker, since I didn't contribute anything except a summary of all that analysis and argument (sans passion) I doubt that I could have saved you anything by coming earlier.

When on a project, a bean diet has the additional advantage that it discourages people from hanging around and trying to talk to you while you are working :) .

I used to have a dog who would be laying on the floor half-asleep, then fart, then jerk his head up and back towards his tail as if startled. He would have this sleepy, puzzled look on his face that used to crack me up every time, "What the heck was that? It sounded like an explosion coming out of my anus! Well, that can't be. Must have been dreaming."