How can an vehicle move faster than the wind that is powering it?

[ThinAirDesign]

Good luck and I will check back from time to time to see if anyone has gotten off of their lazy butts and posted up some videos!

Hey Physics ... if you're out and are not inclined to answer the above, I understand.

Just wanted to thank you for the exchange --- it was fun.

JB

 

[spork]

FWIW, Your vector diagram has convinced me you are right (I think)

That's the most exciting thing I've heard all day. Until now all I've gotten is that my vector diagram is completely wrong in every way - or people refusing to acknowledge it's existence -right or wrong.

But also the vector diagram would also show an ice-boat can not go DDWFTTW, whereas the 'wind trolley' can? D

That's absolutely right.

Because the source of power isn't the wind but the difference between wind speed and ground speed, which is independent of vehicle speed.

I continue to be impressed. It's clear that you understand the concepts and are open minded to the possibility. I'm very nearly certain you'll become a believer.

And my answer is that I don't know for sure. Here is where I'm at:

1. The iceboaters of the planet certainly claim that a VMG downwind is a piece of cake. There's lots of them and only one of me so I'm inclined to follow along.
2. It would seem that you could take all the principles of the iceboats and squeeze them into a cart with rotating sails and the kinematic constraints of wheels to build a cart that will go DDWFTTW.
3. Jack Goodman claims to have built such a cart and posted the Youtube video which gets me excited but is hard to accept for documented evidence as "proof possible" since what we could be witnessing are artifacts of the experiment and like all good experiments really needs independent confirmation.
4. When I try to reduce it all down into an environment that would reduce the possibility of any such artifacts and would be much easier to test, control and document (the cart on a treadmill), I run into the issues I stated on my first post.

It is certainly a quandary.

And that to me is VERY refreshing.

You and I were having a nice exchange, Jeff and I were having a nice exchange. Nevertheless here we are with the betting.

I really only asked simple questions and expected only simple answers but the only one who would do so is you and Jeff.

Well I'm sorry it seems that way. I have tried to answer all questions. The bet is only offered to people that are NOT asking questions - people that are sure they already know the answer.

Why? How confident someone is on his/her position is irrelevant to this entire discussion. I know someone who was confident enough that the Patriots would win the Super Bowl that they dropped 25 large on it.

You have it exactly backward. How much you bet isn't what makes you confident or right. How confident you are governs how much you'll bet. People are insisting they're absolutely right - and that others are absolutely wrong; but clearly they're not as confident as they claim to be.

Here is one thing I will leave you with:
I have now gone full circle on this. I originally argued that it was a "no-way no-how" thing.

And there we are. You didn't come on asking simple questions and wanting simple answers. You came on here ignoring all evidence and telling us we didn't understand physics.

Then as it turned out to be possible with land yachts and iceboaters I could only believe that it's certainly possible to collapse it down to a cart heading directly downwind. When I saw Jack Goodman's video I thought "holy cow I got to build me one of those!"

And all that is great. It proves you were in fact far more open minded than you let on. Don't get too upset if we took you at your word when you said "no way - no how".

Not only did I fail, I wasn't even in the ballpark.

Low drag and efficiency is key. Jack went to a lot of effort reducing drag and making an efficient prop.

The beauty of it all is that this only proves that I don't know how to build a cart that will make forward progress on the treadmill. I'll be the first to admit it. Whether it means that it is impossible to do or that I just suck at it I don't know. That is what is so cool about the whole deal - you can never disprove it but it may be possible to prove it can be done.

I'm glad to hear you say that.

 

[rcgldr]

So here's mine:

Well a heli rotor is designed for high speed, high lift, and has a lot of drag. You need a better propellor, one that can generate around 5 mph of air speed efficiently. I see 3 issues. Losses in the drive train, propeller efficiency with the induced wash issue, and most importantly, if the apparent wind on the blades or a propellor is really different than the apparent wind on the cart.

Drive train: in general, chain or belt drives are more efficient than geared drives.

Propeller - one similar to the Gossamer Albatross, but slower speed still (the Albatross flew at about 18mph), or similar to one of those rubber powered indoor models.

http://en.wikipedia.org/wiki/Gossamer_Albatross

 

[PhysicsAddict]

And there we are. You didn't come on asking simple questions and wanting simple answers. You came on here ignoring all evidence and telling us we didn't understand physics.

Not at all. You read my last post. You know where I stand on iceboats etc. I dropped in, restated the problem from a different angle so I could reduce it to the simplest of questions, then I started asking those very simple questions. Questions that if were met with simple answers would have helped me find my "kink". Questions that would be no different than I would pose to one of my engineers that came into my office with a design in order to have them defend it and help me understand it.

Low drag and efficiency is key. Jack went to a lot of effort reducing drag and making an efficient prop.

I was really shooting for that when I built a set of blades like his using balsa. Maybe fanned out balsa just doesn't scale down too well. Mine didn't even work as good as some of the heli blades. Any Ideas?

Well a heli rotor is designed for high speed, high lift, and has a lot of drag. You need a better propeller, one that can generate around 5 mph of air speed efficiently...

Thanks Jeff. As I mentioned, I did try to copy Jack's blades but that is where I may have snagged. I don't have accurate specs on Jacks blades or even a side-on shot of them to go from. I was just shooting from the hip on those. I was counting on the variable pitch system to cover the bases there. In that original video I also had the cart geared wrong compared to Jack's specs. That's why I rebuilt the cart later.

As for belt vs. gears, when it comes to smaller mechanics, the gears win. I have the components to re-make it using belt drive but I assure you this is far smoother and it almost seems frictionless.

AND if nobody is going to get up and get to carving then please post up a better shot of Jacks blades - a side on shot would be great. Dimensioned drawings would be awesome (Spork? can you get him to send you this info?). When I get back and if no one has made a move toward building their own cart then I will take another run at it if I can copy those blades. In fact, anyone building their own cart is going to need this info.

Thanks guys!

Later!

 

[PhysicsAddict]

Hey Physics ... if you're out and are not inclined to answer the above, I understand.

Just wanted to thank you for the exchange --- it was fun.

JB

Oh and Ditto! I enjoyed it! I'll be around I promise.

 

[spork]

Well a heli rotor is designed for high speed, high lift, and has a lot of drag. You need a better propellor, one that can generate around 5 mph of air speed efficiently.

Incidentally, all my heli blades have symmetrical airfoils. I assume yours does too. That would certainly cost you something. Also, heli blades have no twist. Jack's cart used a blade with "true pitch". That's probably fairly important.

Drive train: in general, chain or belt drives are more efficient than geared drives.

On Jack's cart the drive belt is as loose as he can use it. Also, the pulley's are exactly aligned on the tight side of the belt.

Spork? can you get him to send you this info?

I have most of the info. But how about I get you two in direct contact? He's a very easy guy to talk to.


Incidentally, I'm curious... are most of us believing at least that the ice-boats can and do achieve downwind tacks such that their downwind velocity component is faster than the wind? The cart is intriguing for sure, but I'm wondering if people still differ on the more basic "building block" to this brain teaser of sorts.

 

[Topher925]

Physics Addict,

So here's mine:
http://s167.photobucket.com/albums/u123/DarwinAward/

Great work! I just only wish I had time to finish up my theoretical analysis of this so we could compare it to your experiment and see if they verify each other. Unfortunately, these thermo labs won't grade themselves.

Also, try to keep this thread strictly based on the physical aspects of this device. Comments such as "take the bet" and "nasla says it can happen" are not valid arguments and don't prove or support anything. As I stated on spork's original thread, if posts using non-valid or irrelevant evidence or arguments are used to support your claim then they will be ignored by me and hopefully by all others as well.

 

[ThinAirDesign]

Comments such as "take the bet" and "nasla says it can happen" are not valid arguments and don't prove or support anything. As I stated on spork's original thread, if posts using non-valid or irrelevant evidence or arguments are used to support your claim then they will be ignored by me and hopefully by all others as well.

There is no better "analysis check" than the real world. If your analysis says that the balloon will win every time and the guys racing the NALSA races are beating the balloon every time, it's a pretty fair sign that your "analysis" is wrong.

Ignore the real world at your own peril.

JB

 

[OmCheeto]

There is no better "analysis check" than the real world. If your analysis says that the balloon will win every time and the guys racing the NALSA races are beating the balloon every time, it's a pretty fair sign that your "analysis" is wrong.

Ignore the real world at your own peril.

JB

I'm going to ignore the comments over the last 12 hours because I don't have time for 5 pages of nonsense, along with the fact that I figured it out last night, approaching sleep.

It's a similar effect to either roller skating or swinging on a swing.

Neither roller skates or swings have motors. But the devices in question just seemingly keep on going faster and faster.

It's the energy added by the RC steering mechanism that imparts the seemingly impossible forward thrust to the device.

And do not ask me for force vector diagrams... It's so second year university...

 

[ThinAirDesign]

It's the energy added by the RC steering mechanism that imparts the seemingly impossible forward thrust to the device.

Yes, you finally hit on the well known fact that if you jerk the front wheel of a tricycle back and forth with the right timing, a minicule amount of force can be amplified to astounding speeds unknown.

Brilliant.

JB

 

[Topher925]

Yes, you finally hit on the well known fact that if you jerk the front wheel of a tricycle back and forth with the right timing, a minicule amount of force can be amplified to astounding speeds unknown.

Brilliant.

JB

ThinAir, while I do still disagree with you I do have to admit that I did "lol" a little bit when I read your last post.

 

[spork]

And do not ask me for force vector diagrams...

No need to ask you for any force vector diagrams since I already derived, posted, and explained them in detail. What I just can't understand is how anyone could possibly deny this when such a trivial analysis shows it's completely doable.

If it's so "second year university" why can you not point out the flaw in my diagram?


So the evidence now exists in the form of a simple analysis, GPS data plots, the direct quotes from those that perform this "feat" regularly, and a video showing it in real-time. Not believing this is a lot like not believing we sent man to the moon, or that the 9-11 attacks were a U.S. government conspiracy. There's simply a landslide of information that this happens all the time, and no evidence to the contrary - but people have it all figured out I guess.

 

[spork]

I'm just completely baffled that people don't follow this. Forget about ice-boats tacking downwind (in fact it appears that everyone has conveniently forgotten that). Can we agree that a sailboat can tack upwind? If so - we're done. It's EXACTLY the same thing.

Now my bet is that no one will respond to whether a sailboat can tack upwind. People seem to like to ignore the simple hard evidence.

 

[Topher925]

Can we agree that a sailboat can tack upwind? If so - we're done. It's EXACTLY the same thing.

Of course a sailboat can tack upwind. But NO it is not exactly the same thing. If you actually believe it is the same thing then your logic is seriously flawed. This is not so much a matter of relativity but a matter of kinetic energy and how it is being transferred. The fact that you would even make a statement such as that demonstrates that you do not comprehend the phenomenon you are trying to convey.

As for your vector diagrams, is this the only one that you have made?

http://www.putfile.com/pic/8419299

I have ignored it because its a very poor diagram and really does nothing to model or demonstrate the subject at hand. I would like to see you create a diagram that has a summation of the forces inflicted on the boat assuming its sail is an actual airfoil as ThinAirDesign has suggested. I found that there are 5 significant force components acting on the boat and can be modeled as functions of velocity in the x and y directions an the velocity of the wind. The drag, lift, and wind force coefficients should be the only variables that define the system. Consider them as the eigenvalues or eigenvectors of the system. I used lift and drag coefficients for a NACA 0012 airfoil, perhaps thin air design can give me a more practical airfoil to reference.

 

[spork]

Of course a sailboat can tack upwind.

Well then we should be all done here - since all of us on the physics forum understand how inertial reference frames work.

But NO it is not exactly the same thing.

D'OH! It seems I spoke too soon. Are you actually telling me there's a difference between a boat in calm water with a 5 knot wind vs. a boat in calm wind and a 5 knot current? What if you were in the middle of the ocean with no GPS? How could you possibly tell the difference?

The fact that you would even make a statement such as that demonstrates that you do not comprehend the phenomenon you are trying to convey.

You're embarrassing yourself.

I have ignored it because its a very poor diagram and really does nothing to model or demonstrate the subject at hand.

Yes, you've demonstrated already that you don't understand my completely accurate vector diagram. Although you haven't been able to point out any specific problem with it.

I would like to see you create a diagram that has a summation of the forces inflicted on the boat assuming its sail is an actual airfoil as ThinAirDesign has suggested.

First of all, my diagram does exactly that. Secondly, ThinAir never made any such suggestion.

[lots of nonsense]... perhaps thin air design can give me a more practical airfoil to reference.

Of course - why trust someone with an M.S. in aero on something this simple?

 

[spork]

So, for everyone but Topher, I'm still at a loss on what's left to discuss. Is there honestly any real doubt that ice-boats are doing as claimed?

If so, how can you explain the sailboat tacking into the 5 knot relative wind (on a calm day with a 5 knot current) in the middle of the ocean?

 

[ThinAirDesign]

Of course a sailboat can tack upwind. But NO it is not exactly the same thing.

Topher, does this brainteaser sound familiar?

You're in a sailboat on a day with NO wind. However, there's a 10 knot current taking you directly toward your intended destination. What's the fastest way to get to your destination? Should you drop your sails to reduce drag, or use your sails to get there more quickly? You can only use the energy from the wind and/or water - no paddles, motors, etc.

If you can answer the above correctly, you will see that it IS exactly the same -- that is if your claim that the cart (or sailboat) cannot outrun it's power source was in fact valid, a sailboat would never be able to tack upwind.

You might want to think about it carefully, 'cause it's easy to look silly when dealing with the real world.

JB

 

[OmCheeto]

I must admit that I'm a bit new to this forum.

Is this a perennial Halloween joke kind of post?

 

[spork]

I must admit that I'm a bit new to this forum.

Is this a perennial Halloween joke kind of post?

I don't think so. I think Topher actually doesn't understand inertial reference frames.

 

[schroder]

So, for everyone but Topher, I'm still at a loss on what's left to discuss. Is there honestly any real doubt that ice-boats are doing as claimed?

If so, how can you explain the sailboat tacking into the 5 knot relative wind (on a calm day with a 5 knot current) in the middle of the ocean?

Look, sailboats tack into the wind at an angle, typically 40 degrees. This makes the wind curve around the sails, resulting in a delta velocity, in other words, acceleration. This acceleration is mainly to the side but does have a forward component as well. Also, the keel of the boat tends to redirect the sideways acceleration into a forward acceleration resulting in forward motion. Note, however, that the boat does not move directly forward into the wind as it is always tacking at an angle. Let’s say you have a twenty knot headwind and you tack into it at a forty degree angle. You might typically generate a twenty-four knot speed at an angle of forty degrees into the wind. This is why it can be said that a sailboat can go faster than the wind. But the velocity, as a vector is never faster than the wind. In the above example, the forward component would be about 18 knots, which is less than the 20 knot wind. The boat cannot sail directly into the wind. But I fail to see what all this has to do with a cart on a treadmill. The cart is initially getting ALL its drive power from the moving tread driving its wheels while the cart is held stationary against a backstop. Then the wheels drive a propeller through some sort of drive train. Now you expect me to believe that the force of the propeller can drive the cart forward on the treadmill? If that was true, you could turn the treadmill off and the cart would keep going! In other words, you are asking me to believe in a perpetual motion machine. This thread is an insult to the intelligence and it is about time that a moderator put it out of its misery.

 

[spork]

Look, sailboats tack into the wind at an angle, typically 40 degrees...

Yeah, I'm pretty familiar with how sailboats tack into the wind since I've been sailing for over 30 years.

This makes the wind curve around the sails...

Yeah, I'm pretty familiar with how the wind over an airfoil creates lift seeing as I have in M.S. in aero.

But I fail to see what all this has to do with a cart on a treadmill.

And I really can't imagine how it could possibly be made any simpler. I'll walk you through it. I'm going to number the steps, because I want someone to actually point out where this goes wrong.

1) I think we can agree that a sailboat can tack into the wind.

2) I hope we can agree that if you're in the middle of the ocean and you feel a 10 knot wind over your deck, you can tack into that wind. It doesn't matter whether you're in a 10 knot current and there's no "wind", or there's a 10 knot wind and no current. Afterall, what do we measure the wind relative to - the bottom of the ocean?

3) So... if we are in a 10 knot current, with no wind, and we tack into the relative wind, we'd have to say that we're tacking down-current rather than upwind. But we're going faster than the current. In other words we can tack faster than the fluid that's pushing us.

4) If a sailboat can tack faster than the fluid that's pushing it, an ice-boat can sure as heck do the same (which we already know from GPS data and testimony of the ice-boat racers).

5) Put an ice-boat or two in a huge frame with a seat in the middle and let them tack downwind faster than the wind all day long - while you sit in your seat going straight downwind faster than the wind.

There you go. A vehicle that goes straight downwind faster than the wind, powered only by the wind. Forget about the cart. The object is to build a vehicle that goes straight downwind faster than the wind - and this one does it.

It's now been shown with GPS data, vector analysis, testimony from the very ice-boat racers that do it every day, and finally we can see that exactly the same thing happens whenever a sailboat tacks into the wind.

Now you expect me to believe that the force of the propeller can drive the cart forward on the treadmill?

I would've said yes - but now I think it's a trick question.

If that was true, you could turn the treadmill off and the cart would keep going!

Now you're just messing with me - huh?

In other words, you are asking me to believe in a perpetual motion machine.

I'm curious to know how many times we'll have to explain that this is NOT a perpetual motion machine. How can it be so complicated to understand that this vehicle exploits the motion of the air relative to the ice or water?

This thread is an insult to the intelligence and it is about time that a moderator put it out of its misery.

You actually find this so challenging to your world view that you think a moderator should make it go away? That is an insult to "the" intelligence. But if it's REALLY so obviously impossible, why not take the bet that seems to be annoying everyone? You can claim the $100K and shut me up.

So without simply telling me this is a perpetual motion machine, or that it breaks every single law of physics, someone please point out the step where it all goes wrong. If a sailboat can tack upwind, then a wind-powered vehicle can go directly downwind, faster than the wind - in 5 easy steps.

 

[schroder]

3) So... if we are in a 10 knot current, with no wind, and we tack into the relative wind, we'd have to say that we're tacking down-current rather than upwind. But we're going faster than the current. This tells us that we can tack faster than the fluid that's pushing us.—spork--

This is where you are going wrong. When you tack into the relative wind, you can go faster than the relative wind, but you cannot go faster than the current! Can’t you see that? The sails resist the motion of the boat in the air, which will slow it in the water. But, at the angle of attack the slipstream of air will now be moving faster than the original relative wind. For example: the water current is ten knots. The boat is moving at zero relative velocity to the water but 10 knots relative to the wind. Now you hoist the sails and tack at a 40 degree angle. The wind coming across the sails will be at a greater angular velocity than ten knots (maybe 12 knots) but the boat will actually have a negative velocity in the water of about 1 or two knots. You will never outrun the current which is driving you in the first place!

You actually find this so challenging to your world view that you think a moderator should make it go away? That is an insult to "the" intelligence. But if it's REALLY so obviously impossible, why not take the bet that seems to be annoying everyone? You can claim the $100K and shut me up.—spork--

Where are the details of this bet you keep mentioning? I just might take you up and you can donate the money to Physics Forums after I win. About that video: why is there a need for a tensiometer to be attached to the rear of the cart? After all, if the cart can move forward on the treadmill, that should be very obvious for all to see. The tensiometer adds no useful information. However, the tensiometer might actually be a compressed spring which pushes the cart forward when the prop provides enough lift. That would explain the hoax!

 

[spork]

This is where you are going wrong. When you tack into the relative wind, you can go faster than the relative wind, but you cannot go faster than the current! Can’t you see that?

Of course you can. You're in the middle of the ocean. The current is moving you toward the north at 5 knots. There is no wind - but you feel the 5 knots of relative wind over your deck. You throw a buoy overboard as a current marker, put up your sails, and tack into the relative wind - leaving the buoy in your wake. You're now going north faster than the 5 knot current that's pushing you north. Can't you see that? This is where you are going wrong.

The sails resist the motion of the boat in the air, which will slow it in the water. But, at the angle of attack the slipstream of air will now be moving faster than the original relative wind.

Forget all about the details of how a boat sails. We agree it does. The question is this... how can you even tell whether you're in a 5 knot current with no wind or in a calm current with a 5 knot wind if you're in the middle of the ocean with no GPS etc? Serious question. Tell me what you do aboard that sailboat to tell me which situation you're in.

Where are the details of this bet you keep mentioning?

PM me with your contact info. We'll set it all up.

I just might take you up and you can donate the money to Physics Forums after I win.

Fine. Just don't sign that check until you actually see the experiment fail.

...That would explain the hoax!

Yup - there are lots of ways to explain the hoax - if there were a hoax. But why post a video hoax of an everyday event? This has been proven in just about every way imaginable - including GPS data, vector analysis, and testimony of the people that do it.


No one seems willing to answer the question any longer as to whether they believe ice-boats tack downwind with a downwind velocity component greater than the wind speed (as the racers, GPS data, and vector analysis clearly shows).

 

[Trond]

The bet is for people that are positive this is impossible - people like you.

Then you have misunderstood me completely, I said it was impossible at first on RR, then I pondered about it and changed my mind. However I have a different approach to the proeblem than you do.

 

[spork]

Then you have misunderstood me completely...

I think you're right. What is your current stance?

A) Sure it can be done (and happens every day)
B) Sure it can not be done
C) Unsure and interested in the analysis and evidence
C) Other

 

[Trond]

What is it? I'm trying to have a discussion about a cart and you want to discuss sailing. I'm not sure it means the same thing to you and me.

If you in A) as usual mean if an ice yacht can reach a point downwind faster than the ballon, then yes sure it can be done. Not sure how often tho

But as you know, I'm more interested in the cart.

How is your stance on whether the cart can advance on a treadmill with no wind relative the treadmill.

A) Sure it can
B) No it can't
C) Unsure
D) Other

 

[spork]

How is your stance on whether the cart can advance on a treadmill with no wind relative the treadmill.

I assume you mean no wind relative to the treadmill itself - not relative to the moving belt of the treadmill. In that case the cart can definitely advance on the moving belt.

 

[Trond]

Yes, that is what I mean. No wind relative the room, no wind relative the treadmill itself and consequently no wind relative the cart until it starts moving.

So it's rolling, at the start it's standing still on the belt, propeller turning, driven by the rolling wheels as the belt rolls underneath the cart. We get to the point where it starts to budge.

I trust we can agree that to continue from that point the blades will have to spin faster?

 

[schroder]

Of course you can. You're in the middle of the ocean. The current is moving you toward the north at 5 knots. There is no wind - but you feel the 5 knots of relative wind over your deck. You throw a buoy overboard as a current marker, put up your sails, and tack into the relative wind - leaving the buoy in your wake. You're now going north faster than the 5 knot current that's pushing you north. Can't you see that? This is where you are going wrong.





No one seems willing to answer the question any longer as to whether they believe ice-boats tack downwind with a downwind velocity component greater than the wind speed (as the racers, GPS data, and vector analysis clearly shows).

Yes, you leave the buoy in your wake because you are moving away from the direction of the current at an angle. Let's say the current, the boat and the buoy are moving directly from North to South at ten knots. You hoist your sails and tack into the apparent headwind at a forty degree angle. You are moving away from the buoy at the angle of tacking. Now, there is absolutely no way you can ever get back to a point directly South of where you started before the buoy does. If you think you can, that is the end of discussion! But I admit the same cannot be said about an iceboat and a balloon. However, much of the balloon’s velocity has a vertical component. Remember, the balloon is rising while the buoy drifts horizontally with the current. Also, while the buoy will drift along with the current, the balloon will allow some of the airstream to slip around the surface; it will not necessarily be carried along at wind velocity. Finally, the iceboat does achieve a higher peak velocity than a sailboat. But comparing the iceboat velocity with the balloon apparent velocity is not a direct comparison with the wind. But my part of this discussion is concerned primarily with that contraption moving steadily forward against the treadmill while being powered by the treadmill. I still say that is impossible.

 

[spork]

the boat and the buoy are moving directly from North to South at ten knots. You hoist your sails ... Now, there is absolutely no way you can ever get back to a point directly South of where you started before the buoy does. If you think you can, that is the end of discussion!

I don't just *think* I can get back to that point - I *know* I can get back to that point. In fact I can easily get back to a point further south than the buoy. That's what tacking is all about. So I guess this is the end of the discussion - but before you leave let me offer you a $100K bet on this as well. Frankly I can't imagine why anyone would take me up on a bet so blatently obvious - but it's there if you want it.

But my part of this discussion is concerned primarily with that contraption moving steadily forward against the treadmill while being powered by the treadmill. I still say that is impossible.

No need to go anywhere near the vehicle on the treadmill if we can't even agree that a sailboat can tack into the wind - particularly if the discussion is already over before it really began.

 

[spork]

For those still in the discussion...

Are we generally on board that the ice-boat racers aren't lying to us with their testimony, their GPS data, and their diagrams?

Do we not agree that a typical sailboat can tack into the wind - and thus it's easily shown that we can make a wind powered vehicle that can go directly downwind faster than the wind?

 

[ThinAirDesign]

Now, there is absolutely no way you can ever get back to a point directly South of where you started before the buoy does.

schroder, before you walk away from the conversation, humor me and answer the below question. I'd really appreciate it.


You and I are on a sailboat in the fog. We know that harbour is exactly South of us. As we pop our heads up above the deck, we see that we have a 10knot wind coming directly from the South. You and I both decide that we'll tack upwind to shore. (at this moment, we also drop a bouy into the water to mark our start point).

As we power away from our bouy, tacking zig-zag South towards land, will the bouy get there first, or will we?

Thanks

JB

 

[Trond]

I'll answer
That depends on your boat, sailing skills and whether there is a strong current going south directly to shore. If there were no current at all the buoy wouldn't go south as they seldom go directly against the wind...

And even if there were a 10 knot current going directly to shore it would be hard to beat you even with bad skills as you would then have both the current and the wind helping you...

 

[ThinAirDesign]

I'll answer
That depends on your boat, sailing skills and whether there is a strong current going south directly to shore. If there were no current at all the buoy wouldn't go south as they seldom go directly against the wind...

And even if there were a 10 knot current going directly to shore it would be hard to beat you even with bad skills as you would then have both the current and the wind helping you...

Until schroder gets back to us all I will say is that our sailing skills are perfectly adequate.

JB

 

[Trond]

I don't doubt that as it wouldn't take much to outsail a bouy tacking up wind now would it Jayson