Sailing Directly Upwind

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

 

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

 

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.

 

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.

 

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.

 

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.

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.

 

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.

 

They will stall and weathercock.

 

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...

 

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.

 

-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"

-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!

 

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

 

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

 

{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)

 

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