How Does a Boat Sail Faster Than The Wind?!?!?
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- čas přidán 24. 02. 2023
- How is it even possible for a boat to sail faster than the wind, let alone 2-3 times faster, like this AC72s of the 34th America’s Cup? That’s exactly what we’re going to find out in this video.
Early sailing ships looked like this, and pretty much used their sails as big parachute like drag devices to pull themselves along in the same direction as the wind.
This isn’t very efficient and it’s also impossible for any boat like this to sail faster than the wind.
This is because as the boat accelerates the wind effectively disappears as boat catches up to it.
Instead, modern sailing boats work much more like airplanes which use their wings to generate lift. Except on a boat the wings are oriented vertically instead of horizontally. One wing is the sails in the air, and the other is the daggerboard or keel in the water, also called a foil which is short for hydrofoil. The foil produces just as much lift as the sail even though it’s much smaller, and that’s because water is 800 times denser than air.
Modern sails look much more like a streamlined airplane wing than a baggy parachute.
They also generates lift in the exact same way. As the wind flows over a modern sail from front to back, the sail generates lift perpendicular to the surface of the sail, just like an airplane wing.
Underwater foils like the keel on this monohull come in all shapes and sizes, but like the sails in the air they also generate lift perpendicular to their surface as the water flows over them from front to back.
Except unlike an airplane, where the wings both generate lift in the same direction to lift the plane off the ground, the sails and foils on a sailing boat generate lift in opposite directions, and this is what propels the boat forward.
The tighter the angle between the lift from the wind and water, the faster the boat will go. And the faster the boat goes, the more apparent wind it generates to flow over its sails, which generates more lift, which makes the boat go even faster. And this cycle will continue until the friction with the water prevents the boat from going any faster.
That’s why the fastest boats have underwater foils that provide lift in two directions - a horizontal side force to counteract the forces of the sails and drive the boat forward, and a vertical component to lift the boat out of the water and reduce friction.
None of this would be possible without high tech materials like carbon fibre, epoxy, and Dyneema, which can create structures stronger than steel at a fraction of the weight.
The square rigged ship in this video is the Batavia, which was built in Amsterdam in 1628, more than 200 years before people really began to understand how wings generate lift: en.wikipedia.org/wiki/Batavia...)
And thanks to Trent Palmer for the flying footage - love his channel! / @trentonpalmer
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- There are no warranties, expressed or implicit, about any content or its fitness for a particular purpose.
- There are risks of injury, death, drunkenness, and financial hardship involved in sailing.
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#howto #sailing #howtosail #learntosail #sailingtips
I thought Jordan Peterson was narrating this video 💀
LOL - I’m not sure if that’s good or bad!
@@SailingTipsCait means you have an opportunity for parody my friend.
@@northernmetalworker That could be my new schtick!
No, he called it a boat not a “boot”.
@@SailingTipsCawith some practice you could do big things!
Incredible physics analogy with the two rods and the puck, most intuitive explanation I've ever seen of this
Thanks I’m glad the analogy made sense! There are some subtleties that could benefit from more depth of explanation, like the models of the atom we learn about in high school, but I was really trying to come up with a good way for people to intuitively understand what’s going on!
I'm not into boats but I am into knowing things. This video was randomly recommended and it was very concise and easy to understand!
How does the boat start and maintain movement tho??
Excellent question! A sailing boat can sail in any direction relative to the true wind except straight into the wind as well as a no-go zone about 45 degrees to either side of that (look up points of sail).
To get started you need to position the boat with the bow facing any direction other than the no-go zone, with the easiest being across the wind i.e. bow 90 degrees off the wind. Then you pull in the sails and the boat will accelerate.
Once the boat is up to speed, the helmsperson can either steer the boat to keep the sails optimally aligned to the wind, or the crew can adjust the sails if for some reason the boat can’t be steered to the wind e.g. there is another boat, an island, or you simply want to go in another direction relative to the wind.
Does this help?
+1
@@SailingTipsCa This is a perfect answer, but in practical terms, most sailboats that folks are likely to encounter have motors that sailors used to move the boat into a position where they can start to sail using the wind.
For smaller boats with no motor, such as a beach catamaran, sunfish, or even windsurfer, etc., this is exactly what you do.
Even for boats with a motor, getting under way without using it is much cooler. Sailing off a mooring comes to mind.
had a 18 foot maricat when i was a teenager. nothing to do with this video but mate was it one of best feelings to get it up on one side and ride the wind.
Yes small multis are incredible fun!!!
Finally a channel that asks for a like at the end, not the start. Great video. 🎉
Thanks - I find that annoying too when creators ask for likes before they’ve delivered the content!
@@SailingTipsCa CZcams should auto detect it and delay the upload by 2 hours to teach creators to stop it.
Fun fact, old sailing boats used to put the worst smelling facilities at the front of the ship, since the wind would carry the smell forward and away from the ship.
That’s a great tidbit! These days though you’d probably want to put those at the stern as faster boats are almost always sailing upwind!
Thus the name "head" for the old ship's toilets
@@user-bz1ij8zk6h Lots of interesting origins to many sailing terms!
why not just shit on the water
@@KevinColt that's basically how the toilets worked, with a common setup being a communal trough made of a long plank with 3-8 holes at the front of the ship where you're basically sitting over the side and (mostly) shitting into the ocean. The sea itself would clean off most of what hit the side of the ship and the rest by the poor barnacle boys.😬
Having down quite a bit of sailing when I was younger, I've been very curious about this. Thanks for a simple, clear explanation!
Glad it made sense!
Brilliant, thank you. Ive been trying to understand these boats whilst watching sail gp and just couldnt figure it out. Clear and concsie!
It’s a bit of a mind bender but glad it finally makes sense!!!
Thank you, excellent description and visualization. I learned a lot
Excellent - glad it made sense!!!
Thank you, very amazing! These sail races are really fun to watch
I completely agree!
Thank you for clearing my mind about this !
Glad you found it helpful!
Fascinating and clear explanations. Thanks!
Glad you liked it!
Long time since I've learned something this interesting!
Thank you for sharing it.
I was amazed.
Glad you enjoyed it!
Such a great explanation!
Glad you liked it!
Short and sweet answer to the question posed by the title. Nice one. 👍🏻
Thanks so much - glad it delivered!!!
Thanks much. Good explanation, as usual.
Thanks so much!
Great explanation! I just watched a race video and was wondering why they just had one foil in the water. Your video answered that question too.
Glad it was helpful - thanks for watching!
Very good video and explanation. Thank you
Thanks - glad you liked it!
Ty, wondered how that worked. Great explanation
Glad it made sense!
Puck description is spot on well done Sir!
Glad it made sense!
Brilliant explanation
Thanks - glad you liked it!
Good example with the cap. On a side note, airplane also use multiple vectors of lift. Yes, the wings lift upwards, but also, lift from the propellers provides lift in the forward direction, although we then call it thrust. Still, the blades are still utilizing the Bernoulli effect with an airfoil shape to utilize high/low pressure differentials. Even jet engines require these differentials internally in order to provide the pressures necessary to initiate jet propulsion.
It's all about the pressure.
I’m also a closet airplane buff but sailing boats are slightly cheaper!!!
That's why a C130 Hercules can take off with more weight than the wings can lift at takeoff speed. Those 17,200 horsepower virial pitch turbo prop engines can cork screw the plane up in the air until the airspeed increases to the point where the wings can do there lifting.
@@Paul37Ontario Cool plane trivia - thanks for sharing! With some military planes the engines are so powerful the wings almost seem like accessories!
Bernoulli effect requires a difference, or change, in air velocity, and the difference in air velocity results in changes in pressure. Usually that is provided, in a pipe, by a constriction of the flow area of the pipe (e.g. a venturi in a carburetor).
There is no such constriction for a sail as it is open on both sides. I assume this comment, by invoking Bernoulli, is saying the sail generates a difference in air velocity from one side of the sail to the other. What causes that difference in air velocity?
Or is it perhaps that the sail generates a pressure difference across the sail by diverting the air, and the pressure difference is then the ***cause*** of the difference in air velocity, and not the other way around?
@@BrianTCarcich Yes, anything with an airfoil shape (wings, sails, hydrofoils, props...) is designed to create a pressure difference in the flow of air or fluid on either side of it. That difference then creates lift or thrust, depending upon the application, and it's all fundamentally Bernoulli's principle at work. Dude was such a genius.
So, in the case of a sail, as with all airfoils, this is due to the shape being more rounded on one side and more flat or even concave on the other. This makes the air travel faster around the downwind side of a sail, creating a low pressure zone compared to the upwind side. This in turn produces the forward thrust of the sailboat through the sideways 'lift' of the sail, which is actually more of a diagonal force relative to the boat for most directions a sailboat can go. Not sure if I'm explaining this very well, but there are tons of interesting articles and CZcams videos that do a great job describing how Bernoulli's principle applies to sailing if you're curious.
We call it creating your own wind (on low drag boats), thats why the appearent wind always comes from the front(and way stronger then the real one), even on reach or broad reach, but you cant do it downwind. You have to reach and jibe downwind.
Yes it doesn’t work going dead downwind as you noted!
thanks for the content)
Glad you liked it!
I would start off by explaining apparent wind , and then use vectors
Yes that’s a great idea - fast boats are almost always sailing upwind even when they’re sailing downwind!
there's a crucial detail that should be noted. High performance class boats are able to go faster than true wind on up and downwind lines due to the design that allows the boats to manipulate apparent wind in an unconventional manner. The best example of this is when the AC72/75 is downwind, the trim is changed to an upwind mode as when it is travelling faster than the true wind, it's as if the wind is going backward! So technically a jibe is in actuality a tack
Yes it’s not uncommon for faster boats to be sailing “upwind” all the time! Even my “slow” F-82R trimaran can “bend” the apparent wind forward by up to 90 degrees so we’re always sailing with the apparent wind forward of the beam even under spinnaker!
This topic fascinates me!
I think it’s pretty cool too!!!
great video
Thanks - glad you liked it!
Best explanation
Glad you think so!
I now understand a little bit more about what hydrofoils and dynamic keels do under water, and how it balances the sailboat to prevent it from keeling over and how it might drag, stall, or fail if sudden changes are applied to it.
As a SailGP enthusiast, I'm grateful
Glad it makes a bit more sense now! You’ve probably noticed that once the SailGP boats fall off their foils it takes a bit of work to get them back up there because they have to overcome the drag of the immersed hull. Amazing machines!
@@SailingTipsCa To me the boat falling off or getting on the foils was as intuitive as changing gears, or picking up speed in a bike to help keep it upright. What puzzles me is the things done by the flight controller, and the wing trimmer tandem the grinder/s because the adjustments done by these guys aren't easily shown and maybe a competitive secret.
@@SukacitaYeremia I understand the flight controller will be constantly adjusting the angle of attack of the foils to keep the boat at the desired foiling height based on the boat speed e.g. less speed more angle of attack and vice versa. The wing trimmer will be positioning the wing to power up or power down the boat based on the prevailing wind speed and direction, and in conjunction with the course being steered. Both the foils and the main are hydraulically controlled with pressure created by the grinders.
Have you heard about people who have sailed into the earth via the north pole? Many books and stories on sailors who have sailed into the earth via the north or south pole to the agartha network of cities. Amazing video about sailing and the wind.
I am definitely not familiar so something I will need to look into!
I knew sails worked like airplane wings but always thought the lift of the sail "pulled" the boat. It did not occur to me that there was another foil underneath and the boats motion is the resultant of these lift vectors. Short and sweet vid.
Glad you found it helpful!
The air does pull the boat. The question is in what direction is the pull directed?
Excellent demonstration 👏 forwarding this to a physics teacher
Cool - physics was one of my favourite subjects!!!
Very interesting
Glad you liked it!
I like that you used Trent Palmer's Freedom Fox!
I’m a closet aviation buff and fan of Trent Palmer’s! I once dreamed of owning a plane but boats are much “cheaper”…
@@SailingTipsCa Me too. I can’t get flying out of my head. I keep thinking somehow I can afford it. It’s so expensive! Trent must do well.
@@scottwooster4102 I think he does, apparently his bread and butter is filming driving scenes for car commercials. The other benefit of a boat is that your can camp on it, have a barbecue on it etc so there is more utility in many regards.
as a young (16 year old) guy, I sailed a Comet with my younger brother on Lake Hopatcong in NJ, if we had a 6 mph breeze against out main sail and jib, we could easily reach 10 to 15 mph depending on hard we haled the mainsail close to the plane of the 22 ft boat Eventually, the 90 year old canvas mainsail exploded and we never had the resources to repair or replace it.
Sounds like lots of fun! Too bad you couldn’t repair the main…
When you tack the sail, how does the dagger board tack to change the direction of lift below?
Great question - it really depends on the boat. Some have asymmetric foils that they raise and lower at each tack. This is the most efficient solution hydrodynamically but involves more work for the crew and precise timing. Others have symmetric foils where lift is generated by altering the angle of attack, normally via the helm/rudder in most boats.
Thanks
Welcome!
Interesting. I wonder if you can apply same principles in electromagnetic fields. Will the boat sail faster if the was 3 forces pushing it in a same manner? Is there an angle range for the most efficient thrust? Thank you
I think you could use this technique in any low-friction environment with opposing forces and the third dimension could be levitation which would result in very low drag/friction! I think the optimal angle is a function of the amount of drag/friction, whereby less drag enables tighter (i.e. more acute) angles and higher speeds, whereby more drag/friction requires larger angles but results in lower speeds. Think of it like gears in a car or bicycle!
Hi. Very good vid ! I have a question - what is "needed" to go faster than wind ( is your Tri able to do so ) ? Would be very interesting video to create - It could be called: " What is needed to go faster than wind". Wing mast ? Power to weight ratio ( Sail area to displacement ) equal to ... ?
Good question and video suggestion! Somebody once told me that everything in sailing comes down to lift versus efficiency and I think that applies here too.
Our F-82R trimaran can sail at around 1.2 times the true wind speed, but it has no lifting foils and relies entirely on floatation for righting moment.
Off the top of my head I think that what you "need" to sail faster than the wind is:
1) A powerful sail plan - most boats that can sail faster than the wind have huge flat-top mains, a rotating mast also definitely helps here
2) A hull that is not constrained by displacement hull speed "rules" (i.e. 1.34 x sqrt(waterline length)) so either a planing hull for a monohull, or a multihull with long skinny hulls and a length to width ratio of greater than 8:1, or lifting foils
3) Enough righting moment to keep the mast upright without impacting 2) above, so for a monohull a canting keel definitely helps
Interestingly I have a friend with a Cheetah 30 sport boat, which has a very similar sail plan to our F-82R, a planing hull, and about the same boat weight, but the Cheetah is much harder to sail faster than the wind because we run out of righting moment and get knocked over as the apparent wind comes forward. In fact the F-82R has about five times the righting moment of the Cheetah and as a result the F-82R rates about 30 seconds per mile faster. The F-82R also has a rotating mast but I think the righting moment is the biggest contributor.
@@SailingTipsCa Thank You!
I have a 24 ft monohull with a Dacron sail. While it is light and efficient it has no foils or Alma’s ( outrigger multiple hull sponsons). I frequently sail at wind speed + 2 knots. The trick downwind is to not sail exactly downwind but off the wind in order to create the draft effect on the sails. That’s why you see sailboats jibing downwind to get to a point that is directly downwind from the boat. Longer distance but much faster speed.
Light weight and with it low drag. I had a 24 mtr cat before with 9 tons and 1 to 19 ration waterline. Same thing without foils or planing.
imagine what and old sailing ship captain would think if he came to the future and saw what a modern sailing vessel was capable of. he'd have us all burned at the stake for sorcery XD admiral nelson's HMS Victory plodding along at 9 knots and then an america's cup catamaran zips past him at 80 knots with its hull floating out of the water going UPWIND. their brains would melt trying to make sense of it.
I know - even 30 years ago it would have been unbelievable!!!
I'd say the Captain would have understood the basic principles, but also figured out that our ships are far stronger and lighter than anything he had to work with. He would also have recognized that a ship designed to carry over 100 cannons plus their ammunition along with food and water for several weeks on high seas along with onboard repairs out of carried and local materials would be a very different design than a vessel optimized for pure speed over a matter of hours.
The Captain would have been amazed at it and definitely want to take a tour of the catamaran, but he would have understood the basic principles.
@@toddkes5890 you're completely clueless. HMS victory was the cutting edge of naval technology in nelson's time, and it was powered by parachute sails. if he intuitively understood how airfoils and hydrofoiling worked he'd have been a genius on the level of newton. sailing upwind is so counterintuitive it took the human race five thousand years to figure out. NO ONE is gonna say 'that makes sense' just by eyeballing it.
@@toddkes5890 Those >100 cannons and their ammunition is going weigh a lot so hopefully anybody with access to high-tech sailing materials is also going to have access to high-tech weapons that are a bit lighter!
@@oldfrend He didn't fully understand the airfoils and hydrofoils, but the Lateen sail that allowed the airfoil effect of sailing upwind was developed in 900 AD. That is over 800 years before HMS Victory was laid down.
He would not have known the mathematical models to get optimal performance, but as a Captain of a warship in a nation that relied on the skill of its ship Captains, he would have understood the basics.
Is there a difference in speed when going upwind vs downwind in the same conditions (edit: angled to the wind for max speed)? Also a vector question. Mostly it's rhetorical, because I'm sure it differs depending on the boat, but mine is a sailing dinghy with a cat rig (edit: not a keel boat, but let's pretend it is). I'm wondering if the goal is forward motion would you end up at the same place at the same time in a dead run versus a broad reach. Obviously upwind has no corollary (edit: actually it does, would you end up at the same place at the same time in a close haul vs the speed of the wind?).
Good questions! Yes there is generally a difference in speed upwind vs. downwind relative to the true wind, and that difference depends on the boat. In my boat I max out at around 12 knots of boat speed when sailing as high as possible into the true wind, but can sail at 20+ knots off the wind.
For all boats the fastest way upwind is tacking through 90 degrees, and for fast boats the fastest way downwind is also gybing through 90 degrees relative to the true wind, as this keeps the apparent wind forward of the beam which keeps the sails working as wings and is much faster than sailing dead downwind.
When sailing dead downwind you can really only go 50-60% of the true wind speed, say 5-6 knots of boat speed in 10 knots of wind. But gybing through 90 degrees downwind my boat could go 12 knots in 10 knots of wind, so twice as fast, but only sailing 1.4 times the distance, so velocity made good (VMG) towards the finish is better even though we're sailing further.
Assuming the same apparent wind angle, the max. downwind VMG is 1 true wind speed greater than the max. upwind VMG. But that is only valid for very efficient sail craft like those foiling boats, or ice boats.
There is type a plot called a speed polar that gives the speed of the boat for all directions relative to the true wind. E.g. see here www.google.com/search?q=sailing+speed+polar&tbm=isch
Offwind (when the dot, a.k.a. scalar, product of the boat's velocity vector with the true wind velocity is positive), for some boats the downwind component of the boat's velocity vector is greater than the true wind's velocity vector. So those boats, with velocity vectors 10-30° off the true wind vector, could beat a balloon blown from an upwind mark to a mark directly downwind, even though those boats would go out to the side with respect to the straight downwind course, gybe, and come back to the downwind mark.
Nice
Glad you liked it!
Newton: “Every Action produces an equal and opposite opposite reaction”
Sailing: “Some actions produce a 90°ish and faster reaction”
I think if you break all the forces down into their vector components Newton is still right, but there are a lot of forces which muddies the waters!
The video explains the sailing dynamics of a high performance keel boat but it doesn't explain why the boat sails faster than the wind. There are many high performance racing boats but they don't sail faster than the wind. The video talks about reducing drags but it doesn't explains it. There are differences between a classical displacement hull, planning hull, and hydrofoil boat. This super short video makes sense for someone who already know how to sail. A beginner who doesn't know much about sailing will have trouble understanding the concept, maybe he can recite the video by rote but not understanding the concept.
The goal with this video was to help people visualize the forces involved. The ability for the boat to sail faster than the wind corresponds to the angle between the rods which are “squeezing” the boat forward. With the wind dead astern the rods are at 180’ and the boat can move no faster than the rods, and will realistically be much slower. As you reduce friction (i.e. drag) you can decrease the angle between the rods to make the boat go faster, like gears in a car. The fastest boats will have the smallest angle between the rods and be able to sail at 3-4 times the speed the rods are moving, which to date is about the limit on liquid water. But ice boats have much less drag yet and can sail with the rods at even tighter angles, and therefore sail many times faster than the wind.
Got it, magic.
I know - it really seems like it!
Having sailed Olympic class tornadoes in the 70s I can tell you that this is quite a feeling to sail a boat extremely fast, apparently making its own wind. Tacking down wind will blow your mind.
You would definitely get a similar sensation sailing a tornado!!!
I fully understand how sailing faster then the winds works, but your way with the two rods are the most random way of explaining it
Another analogy is “shooting” a watermelon seed from between your fingers by squeezing it…but most watermelons don’t come with seeds anymore!
Nice
🌻🇮🇸
Glad you liked it!
I used to wonder that question until I figured it out, wait until my design goes to market. In correct if you are able to create a design that uses the compression of the energy wave that is created at speed, the ship speed ends up being incredible.
Look forward to hearing more about your design!
Just a few things to line up before I move forward ;) @@SailingTipsCa
I've demonstrated this by "shooting" a water melon seed by pinching it between my index finger and my thumb.
That’s exactly what it’s like!
Wtf I never knew. This is very interesting.
I think it’s super interesting too!!!
By a lot less drag than the Nina, Pinta, and Santa Maria....A LOT LESS !
Yes those boats did have a lot more drag…cool names though!
Your're talking to a guy that flew a Pheonix 18 on one hull most of it's time on the water at Santa Cruz, CA, @@SailingTipsCa
@@waltsnow1762 That sounds like a ton of fun!!!
I'm curious if there's a primitive way of making hydrofoils.
Using those natural glues from various trees as epoxy and layers of various bamboo or whatever other trees.
Interesting question! Foils need to be incredibly strong for a very small surface area so they are typically made from carbon fibre and epoxy, vacuum infused etc. My guess is that it would be difficult to get the strength required from other techniques but it might be interesting to try!
1:47 l'd say that foil lift is more directed to the aft than to the bow.
Really - why do you say that? I understood lift to generally be perpendicular to and corresponding in magnitude to the curvature of the foil. Therefore with symmetric foils which most boats have the lift would be perpendicular or slightly forward of the centreline of the boat no? resources.system-analysis.cadence.com/blog/msa2022-exploring-the-aerodynamics-of-symmetrical-airfoil
My understanding is water is essentially incompressible, especially under normal conditions. It's why depth charges work. So how do you have areas of high (compressed water) and low pressure (expanded water) under the keel? Especially as the (compressive??) forces involved must be tiny. 1m.38s
"Essentially incompressible" means that the volume doesn't change much, despite high pressure differences, not that there are no pressure differences. The air that interacts with the sail is also "essentially incompressible" at those speeds (way below Mach 0.3).
Yes incompressibility relates to water not changing volume much under different pressures, not that it can’t be under high or low pressure! It’s the low pressure that substantially lowers the boiling point to be at or near the sea temperature. Check out this video on Vestas Sailrocket for more info on that! How Did Vestas Sailrocket 2 Smash the Sailing Speed Record?!?! czcams.com/video/K3m06731BQY/video.html
You can definitely change the pressure of water in sailing and marine applications. Just look into propeller-driven cavitation if you don't believe me.
My prediction before watching the video:
The forces must be equal, but a lot of slower air in a massive sail can equal the force of some small vanes going forward quite fast.
Pretty much…and maximizing lift while minimizing drag!
Interesting. If this is correct and made a static situation we could generate power without windmills?
I think you still need kinetic energy turned into electricity by some motion.
Yes a static situation could generate lots of force but to generate electricity you generally need to spin a magnet inside a coil of wires (or something similar) so you need the motion!
Does the underwater daggerboard kill sea life? I mean can like a whale or porpoise or fish or sea turtle hear the sailboat coming and move out of the way or are they just sliced open? Is there anything mankind does that doesn't hurt nature?
It’s certainly possible that an underwater daggerboard could harm sea life, however they do tend to make quite a bit of underwater noise which gives most sea life ample time to get out of the way.
Is it rue that the water left behind the trailing edge of the foils on the AC cats gets as high as boiling temperature? Seems hard to believe, I know, but I read that somewhere a while ago.
You probably mean cavitation. The water is not boiling because of high temperature, but bubbles are forming because the pressure is reduced by the foils.
Yes it’s more a matter of the boiling temperature of water dripping towards sea temperature due to the low pressure, and not the water being heated. I show a clip of it in this video: How Did Vestas Sailrocket 2 Smash the Sailing Speed Record?!?! czcams.com/video/K3m06731BQY/video.html
@@albatrosssoaring1487 I recall that they said boiling temp.
@@joeblow1942 Yes, boiling temperature is pressure dependent. If you reduce pressure enough, water can form bubbles at the temperature of the sea. Look up "cavitation".
Try Ice Sailing. Apparent wind ends up almost nose on. "Close Hauled" takes on new meaning. Everything is great until a lull! Then the apparent wind ends up BEHIND the sail. At which point the sail pulling as hard as you can hold comes at you! Very exciting at 60 mph on skis with a windsurf rig. Bonus is, unlike water which a trained eye can see gusts and lulls, little or no such hints at a change in wind speed or direction are readily available on a frozen lake. So if you want to find the razers edge of sailing, have a go. :)
Some ice boats can sail apparent wind angles of less than 7°, so they can sail more than 8 x windspeed across the wind. They can also have a downwind component of more than 4 x windspeed, and an upwind component of more than 3 x windspeed.
Ice sailing looks completely crazy! I think I’d try a BloKart (wheeled buggy) first to get the hang of it!
@@SailingTipsCa Thing with ice sailing, you need to fully INTEND to go fast to do so.
It is the best "ragged edge" thing I ever did. At anything over 50mph each second feels like you will wreck in the next second, mostly due to what is propelling you, the sail, is also trying to smash you. Being backwinded into glare ice at warp speed is at best obnoxious. Good thing is, on glare, you only hit once. :)
@@SailingTipsCa Ice boats have been achieving the wind-speed multiples of the most recent foiling boats for over a century now. But ice sailing is less widespread, so many still have problems understanding and accepting this, even among sailors.
@@bradkubota6968 Even though I live in Canada I’ll have to find someplace a bit colder in the country to try it!
It surprised me to hear Jordan Peterson! 😂
I don't know why the algorithm promoted this video but i am happy to have watched it! ⛵️
You’re not the first person to say that I sound like Jordan Peterson - glad you liked the video!!!
Good video, but no love for Trent Palmer for the flight footage?
I love his channel and I’ve added a thanks to him in the video description!
I would love to learn what the most well designed ship would look like, if it had to use materials available in the 17th century, and also carry cannons.
That would be very interesting, kind of like that test they did with modern sailors recreating Shackleton’s escape from Antarctica using period materials, clothing, and food!
I think over the 100s of years of sail ship evolution, they pretty much nailed it down what worked and what didn't. Ships wouldn't look much different, imo.
@@after_midnight9592 Except that in the 17th century they didn’t yet understand how to create lift with wings - that came later!
Just so people know, the primary purpose of a dagger/centreboard is to counteract the leeward push of the wind. If you’re sailing a dinghy with the centreboard raised, you’ll soon know about it on a reach.
If you have to go on a downwind run though, pulling the centreboard all the way up reduces drag and gains you some more speed, especially if it’s only a light breeze.
Foils on the other hand generate vertical lift, raising the entire boat out the water.
The term “foil” can also be a general term for any underwater appendage that generates lift, including rudders, daggerboards, and of course lifting foils.
Really fast boats are always sailing with the wind well forward of the beam, so you are still relying on the daggerboards to generate lift and maximize performance even when going downwind, although you can pull them up part way to reduce drag.
Even my non-foiling F-82R trimaran will sail with the apparent wind at 45-60 degrees under spinnaker while the true wind is more 90 degrees aft of that at around 135-150 degrees true.
The simplest physics explanation is that momentum is always conserved. Mass 1 x velocity 1 = mass 2 x velocity 2. Clearly it is possible for v1 to be different than v2.
Yes that is a very simple physics explanation! How do you take into account lift versus drag?
Fast boats are generally pretty light and slow down fairly quickly when the wind dies!
@@stingtheweimaraner that is where efficiency comes in, specifically:
Above the water, the limit is set by the efficiency of the sail diverting the side (cross-boat-velocity) component, which is constant, of the apparent wind relative to the increasing drag of the anti-boat-velocity, which increases with increasing boat speed. Key points: the only thing the sail has to work with is the side component of the wind vector, and that does not change with boatspeed; what does change is the angle of the wind on the sail i.e. apparent wind moves forward with increasing boatspeed, and that affects the efficiency with which the sails operate.
Below the water, basically the same thing: the side force, and therefore the leeway velocity, is more or less constant; the drag of the underwater surface increases with boat speed.
So the ability of the sail to generate forward force, i.e. its efficiency, decreases with increasing boatspeed as the apparent wind goes forward, while the drag forces increase with increasing boatspeed. The speed limit is reached when the forces are balanced.
Did you get that clip with permission from Trent Palmer?
I incorporated Trent’s clip into this video under fair use and let him know as a courtesy.
Dang i didnt know these ships worked like this
And now you do!!!
@@SailingTipsCa definitely. Hats off to the inventor that's a damn trick there works so well i'm gonna laugh lol
This is only true when the boat is not travelling in the same direction as true wind right? Can a boat travel faster than true wind in the same direction as true wind? Assuming the wind is constant
Fast boats typically tack through 90 degrees going upwind and also gybe through 90 degrees going downwind as that’s much faster than sailing dead downwind! In other words the are typically sailing across the true wind to some degree although the apparent wind they are experiencing due to their speed is always from ahead.
@@SailingTipsCa So for example there is an island 35km north from my boat. There is a wind heading directly north at 35km/h. If I travel exactly straight north in the exact same direction as the wind, it would take me 1 hour to get to the island? But if I zigzagged back and forth I could get there in faster than 1 hour?
@@mcdonaldslover52 Sailing dead downwind is not very efficient because you effectively “outrun” the wind so you’d be lucky to get 50% of the wind speed as boat speed so it will take you about two hours. On the other hand if you gybe back and forth in a zigzag you’ll travel about 1.4 times further, but you’ll also be able to achieve more than twice the speed so should be able to make it in about an hour in a fast boat.
@@mcdonaldslover52 yes, depending on the boat. Also, it is possible to build a land device (not a boat, but something with wheels) that can go DDWFTTW -- Directly Downwind Faster Than The Wind. It's been built and proven.
You're wrong about the square riggers. Unless sailing down wind, they used the same principle.
How did they generate lift to weather below the waterline without foil-shaped keels?
@@SailingTipsCa
The sails are flown at an angle (from centerline) to produce the lift. Into the wind - you would tack.
Very basic sailing information, try Wikipedia or some books on square riggers.
@@BIG-DIPPER-56 Yes I understand the sail part and a long straight keel would let them reach somewhat, but they wouldn’t be nearly as close-winded as a modern sloop with fin keel, and were therefore very vulnerable to being smashed on lee shores!
@@SailingTipsCa
???
Of course
???
@@SailingTipsCa anything pushed sideways through the water will generate lift; the shape of a well designed foil does better (has a higher lift-drag ration) than a hull without a keel, and the square rigger's sails are also not efficient upwind, but square riggers could definitely make ground to windward.
The name of the game is efficiency.
From my understanding, foils don't produce propelling forces at all. They lift up the boat vertically to reduce drag and stabilize it in the water so that the boat doesn't sweep sideways.
I totally did not understand the physics of the foil's forces shown in your examples. 🤷♂️
The word “foil” is a general term for wing which can do multiple things: 1) a rudder is a foil that steers the boat 2) a daggerboard or keel is a foil that opposes the force of the sails to drive the boat forward 3) a lifting foil raises the hull out of the water to reduce friction. An efficient boat can still sail slightly faster than the wind with only the first two, but to sail at multiple times the wind speed you also need the third to lift the hull out of the water. The foil at 2:32 of the video provides lift in both the vertical and horizontal planes to carry out jobs 2) and 3) with a single foil. Does this help?
@@SailingTipsCa 1:50 - Author. You misunderstand, therefore, you draw the balance of power incorrectly.
Your 'Foil lift' propels the boat forward. This is nonsense.
In fact, this force is always opposite and equal in magnitude to 'Sail lift'...
@@MikleM1 Yes i did say the foils and sails generate lift in opposite directions but the drawing could definitely be better in that regard!
@@MikleM1 "2) a daggerboard or keel is a foil that opposes the force of the sails to drive the boat forward" is correct. The sails propel the boat forward, but won't do so without the opposing action of the keel or foil. Note that he is saying that the sails drive the boat forward.
@Timo Rieseler The video shows an "L" shaped foil that has a vertical, lifting part of the foil (which is horizontally oriented) to raise the boat out of the water and a horizontal part of the foil (which is vertically oriented) to counteract the side (component of) force from the sail. A single foil does two things: vertical and horizontal lift.
Horizontal lift is always needed in a sailboat in order to counter the side force of the sail.
It's also possible to have a foil that only resists the side component of the sail force. That's a daggerboard or regular keel. They have only a vertical member.
There are several possible arrangements of foils, including ones placed diagonally that also provide both vertical and horizontal lift components from a single straight foil, curved or C foils, "J" shaped, "L" shaped, etc.
Seems some what similar to how a surfer can often go faster than the wave they are riding.
Possibly, but I think that’s also a factor of the waves slowing down in shallow water while at the same time getting steeper which provides more of a “slope” for the surfer to slide down and outrun them!
I’m a kitefoiler, it is so Amazing to go faster than the wind 🤙
Yes kitefoilers do it all the time - never tried it but looks like so much fun!!!
@@SailingTipsCa 👍
So that's why Adrian Newey interested in boat racing
There is so much physics involved which keeps things interesting and we’re always learning new things, which is what keeps many people engaged!
I believe an even trickier question is, how a boat can beat a balloon downwind!
If these boats are gybing through 90 degrees downwind they will sail about 1.4 times further than the balloon but travel 2-3 times faster so I think the boat will win!
Silly question. Why would it not? It is not just a pushed by the wind forward.
Most things floating in the air e.g.balloons, bubbles, dandelion seeds don’t got faster than the wind, they go the same speed or slower. And many people find it counter-intuitive that unlike these things, a boat that is “pushed” by the wind can go faster than the thing that is “pushing” it…
@@SailingTipsCa Thinking is always counter intuitive for most people I know. I have been sailing on ice once, and learned physics. Sorry.
@@thepetyo LOL you’re absolutely right!!!
Что только не придумают, если за дело возьмутся грамотные специалисты.
Yes I completely agree!!!
I kinda understood that
I suppose that’s better than not understanding at all!!!
Jordan peterson has a new hobby
LOL with a suspended license why not get into sailing?!?!?
magic hehehe
I know - almost seems like it!!!
The Batavia in all it's glorie, sad to see the condition it's in currently.
Have you seen her recently and if so where?
@@SailingTipsCa the replica is moored at a small museum ship wharf dedicated to her, Lelystad the Netherlands
@@Zero-oh8vm Fitting since she was originally built in the Netherlands!
Explanation via forces and vectors: Drag (force in N) in - opposite - wind direction, Lift (force in N) orthogonal to Drag. The vector of the resultant force is splitted other wise: into sailing direction and orthogonal direction. The force in the sailing direction moves the boat forward and the other one heels the boat sideward. The keel must be heavy to create the sufficient righting moment in order to prevent the capsize.
de.wikipedia.org/wiki/Physik_des_Segelns#/media/Datei:Wirkung_des_Windes_bei_Amwindkurs.svg
Nice diagram - thanks for sharing! Yes the sails generally create more heeling force than forward drive. Most boats use heavy lead keels to create righting moment and counter heeling, but some boats (e.g. multihulls) use floatation and the weight of the boat itself to counter heeling, while others (e.g. foiling boats) use hydrodynamic forces in conjunction with the weight of the boat.
Needs windmill build same
You said ancient sailing ships could only go down wind. That is wrong. The ships you pictured from the 1600s -1700s sailing up to 2 points off the wind.
They could reach a bit but still had to be very wary of sailing too close to a lee shore because their lack of upwind sailing efficiency often led to them being pushed into the rocks by an offshore breeze.
Because it's about energy, not velocity.
Some would also say lift versus drag!
kph?
Sigh…I know…I had to take a shower after I did it…
as long as you know@@SailingTipsCa
00:16 İt's not inefficient because they need force in those big heavy ships instead of speed and it should be able to continue travel even when wind is weak if they were using other sail types it would be like trying to go in fifth gear when you're literally unable to even go as fast as 40 km/h, so don't make old tech look like bad those sail types was so efficient but if you are going to manufacture a car with 18 wheeler truck transmission than it's Gonna be trash
Yes but if those old sailing ships had the exact same sail area configured more as wings like a schooner or modern sloop even they would have been faster!
@@SailingTipsCa they were already have that knowledge but they didn't because it wasn't practical when average wind speed on ocean is not more than 6 m/s and a bulk ship designed for travel usually and get wind speed higher than 8 m/s rarely even if it was designed like that you said it would get higher max speed but it would cost them ridiculous amount of average cruising speed when it's most important specification is that also those ships had hull speed as a limit and when you reach %80 of hull speed amount of power to get speed gets ridiculously high till you exceed that speed and Start to Surf on water and as you can guess if you were able to get that speed still you would need a very high power for a short time to exceed the hull speed than you would be able to maintain that speed but you wouldn't get that powerfull short wind so don't underestimate old tech and don't spread misinformation
@@eshabbatan9411 The ship at 00:16 is the Batavia completed in 1628, and wings weren't well understood by humans until at least the mid 1800s, so how could they have had that knowledge then? Also, how would a wing-shaped sail that would enable them to sail at a higher percentage of the wind speed/hull speed be a bad thing? These old ships were also very vulnerable to lee shores and many were shipwrecked because they couldn't' escape and were blown onto the rocks, so wing-shaped sails that enable them to sail upwind would have been very helpful, even if they couldn't exceed hull speed.
Look at junk sailing boats they knew the only way to travel wasn't drag force but because of strength and durability they made ships with fixed sails so much also you said with the same wing area you could make it much more powerful yes it's true but with same height you couldn't make it more powerfull and you can't make so high sails because it would lay down the ship so you would rather a low center of gravity(within the lift and drag force of wind, I don't talk about center of mass) so a wide horizontal sail would be better than a vertical very high (maybe 4 times longer than ship length)
I mean the cost of sailing faster was so much so they didn't use it because in those times sails and woods were less affordable think about that at those times your problems were not depression or something like that your problem was that you are hungry😅 you need a home to be protected you need water and basic needs like that so it was just a luxury to be fast but making the most basic ship was a need
I’ll speed it up…
The sail is a wing (airfoil).
Yes most modern boats typically use airfoils both above (sails) and below (keels, daggerboards) the water!
@@SailingTipsCa the two rods and puck was an excellent graphic aid in demonstrating the effect. Great job!
@@garyowen9044 Glad you liked it!
I have sailed all my life and I know that this works while at the same time breaking The First Law of Thermodynamics which is that
‘The amount of energy gained from something cannot exceed the amount put in’
I cannot get my mind around it
You are confusing energy and speed. There is no speed conservation, and every lever or gear box can output higher speeds than you put in.
@@albatrosssoaring1487
Okay, thanks for that. Please help me here, I am peddling a bicycle in first gear at four miles per hour, I change up to second gear, keep peddling at the same rpm and therefore double my speed but only if I contribute twice as much energy to achieve it. Right or wrong?
@@mossden It depends. If you keep the pedal RPM and the force on the pedal the same, then the energy input also stays the same, but your output force and thus acceleration will be less. Mechanical advantage means trading force for speed (or vice versa). In higher gears you get more output speed at the price of less output force (less acceleration).
@@albatrosssoaring1487
Just so but I still marvel at a machine which is travelling at four times the speed of the wind that is it’s only power source.
@@mossden Think of the power source as two huge and massive bodies (water-mass and air-mass) that are squeezing out a tiny little boat. No matter how slow the big masses are moving relative to each other (true wind), they still have more than enough energy to propel the little boat much faster than that. And the boat cannot outrun it's power source, because it is immersed in it, as there is wind everywhere around it.
The sail?
LOL yes that’s a very important part of it!
So like traditional chinese sails😮
You mean like a junk rig? I wonder if they had keels/underwater foils…
@@SailingTipsCa yeah, they too are not directed into the wind but at an angle. But I don't think they had underwater foils. But their huge rudders must have had the same effect.
Your fastest angle of attack is between 5 and 20 ‘ off of straight into the wind she’s actually being pulled threw the water not pushed fun fact your slowest speed is going completely with the wind on a Run as they say also the most hot and boring as u are doing the same speed as the wind or slower and u don’t have a breeze because you are the breeze also a hydro foil basically glides threw air more then water so she is slipperyer then a fish in a sense
Except in a really fast boat the apparent wind is always well forward of the beam regardless of where the true wind is!
One word answer....'lift'
Yes…that would be a very quick video!!!
Good video, but it needs a little more time on angle of attack, particularly how the apparent wind eventually hauls so far forward that the angle of attack becomes non-productive.
People who are curious about this will find this Veritassium video especially intriguing
czcams.com/video/jyQwgBAaBag/video.html
Yes that’s a cool contraption!!! And you’re right that I could have spent more time on apparent wind, but also wanted to keep the video short, so maybe another video is warranted!
Try Ice Sailing. Apparent wind ends up almost nose on. "Close Hauled" takes on new meaning. Everything is great until a lull! Then the apparent wind ends up BEHIND the sail. At which point the sail pulling as hard as you can hold comes at you! Very exciting at 60 mph on skis with a windsurf rig. Bonus is, unlike water which a trained eye can see gusts and lulls, little or no such hints at a change in wind speed or direction are readily available on a frozen lake. So if you want to find the razers edge of sailing, have a go. :)
Considering the rods, the angle between them is “tighter” close hauled than for instance a beam reach, indicating the former should be faster according to this ‘theory’. The opposite of reality.
The moderating factor is the friction of the boat with the water, so it’s almost as though the close hauled gear is too “tall” for many boats to overcome the friction, whereby a beam reach is a better “gear” for most boats. The more efficient the boat the closer you get to sailing close hauled all the time, regardless of the true wind direction. On very fast boats there is only a few degrees of difference in sail trim between upwind and downwind sailing.
@@SailingTipsCa Nonetheless this rod explanation doesn’t explain how a boat can sail faster than the wind because it is an analogy and a substitute for the physical explanation. Granted it helps people to see that the opposition of lift from keel and sail is what enables the boat to sail other than downwind. But you say ‘’the puck moves faster than the rods themselves, this is exactly how a boat can sail faster than the wind’’. ie because the angle is acute like a wedge the puck will move further by the ratio of lateral rod displacement over sin theta, which is Simple Machine Theory, but misapplied. You cannot just take the force vector, multiply it by this ratio and call it velocity. 1) that doesn’t give velocity and 2) the lift vector is perpendicular to the rod so the ratio gets inverted anyway. This is where the analogy becomes a fallacy.
The boat reaches maximum speed when aerodynamic force is equal and opposite to hydrodynamic force. This in turn depends on the hydrodynamic and aerodynamic lift/drag ratios. The minimum apparent wind angle is a function of the sum of those two ratios. That is the bottom line. Hence, by the sine rule, the requirement for sailing faster than wind is: sum of both L/D angles < half the true point of sail. Eg close hauled at 45 deg you can sail faster than the wind if the L/D angles sum to less than 22.5 deg.
@@XPLAlN Yes it’s not a precise explanation, kind of like the models of the atom and electricity that they teach in high-school which aren’t completely accurate either, but allow non-scientists to get a sense of how it works.
@@SailingTipsCa ok fair enough.
Generally, the smaller the apparent wind angle that you can sail (maintain speed), the greater speed (true wind multiple) you can achieve. The acute angle between the rods is analogous to the achievable apparent wind angle, which is the sum of the two drag angles (atan(D/L)) at water and air.
Plus crew eating beans help
LOL as long as the crew is facing the right direction!
Apparently its not apparent 😊
Apparently so!
czcams.com/video/LKLa8_GOuPg/video.html "the sails and foils on a sailing boat generate lift in opposite directions"
1) Diagram is a little misleading: the water foils' lift will be perpendicular to the velocity vector of the boat, which is roughly the centerline of the boat, plus a small bit of leeway. On the AC72 the foils my be asymmetrical, which could reduce the leeway wrt the centerline, possibly to 0.
2) This picture diagram should be about total force, not "lift"
2.1) Overall the ***TOTAL FORCE*** (LIft **PLUS*** Drag) vector on the water foils points mostly toward the windward beam (~lift) and a little aft (~drag) i.e. assuming a high lift/drag (L/D) ratio. I say ~lift and ~drag because the boat velocity is ~aligned with the boat centerline (see 1 above).
2.2) Overall the ***TOTAL FORCE*** vector on the sails (air foils) points mostly to leeward and a little fore-ward.
2.2.1) The large lift component vector is perpendicular to the apparent wind vector (by definition of lift);
2.2.2) the smaller drag component (again, assume high L/D) is parallel to and downwind with the apparent wind vector;
2.2.3) the combined Lift+Drag sailforce vector is mostly perpendicular, but slightly downwind wrt the apparent wind vector.
2.2.4) Because the apparent wind direction (arrow tail) is rotated to windward (i.e. perpendicular to centerline) forward wrt the centerline, that rotates the total sailforce vector on the sails forward wrt to abeam. This is the ***ONLY*** source of fore-ward force on the boat.
2.2.4.1) As the boatspeed increases, the apparent wind moves forward, and that rotates the total sailforce vector aft i.e. the along-centerline fore-ward force decreases.
3) When the boat is accelerating, the two force vectors, on the water foils and the air foils, make a wide V somewhat like the picture at 1m46s, only the water force is slightly aft and the sailforce is slightly forward. This is when the watermelon seed analogy is in play.
3.1) As the boatspeed increases, the V between the water-forces and the sail forces gets wider, until eventually the vectors are parallel, opposite and equal, at which point the net force is 0, so the boat moves at a constant velocity.
4) The limitations to speed along the centerline are
4.1) the efficiency (L/D ratio) of the sail to generate its total force as close to perpendicular to the apparent wind as possible,
4.2) the decreasing angle of the apparent wind wrt the centerline of the boat (rotates sailforce vector aft)
4.3) the increasing drag on the foils.
Yes there is some nuance in the physics involved that is beyond demonstrating in a short video, however the intent intent is to help “normal” people visualize and understand the concepts involved, similar to the models of the atom taught in high school, which are also missing nuanced details.
I did think quite a bit on how to present the lift diagram, given the nuance you described above, however chose to present it as I did because in tidal waters there is typically also current at play which contributes to the motion of the boat. For example in the waters where I typically sail it’s not uncommon to have 3 knots of true wind opposed by 3 knots of current, in which case you will have 6 knots of apparent wind before the boat even starts moving, and the heading of the boat no longer aligns with the speed over ground.
The analogy shown at 1:51 is very good. Here is a similar one, that shows how you can outrun the moving air-mass in the downwind direction:
czcams.com/video/ZRnckbYeoRs/video.html
Thanks glad you liked it! I hadn’t seen the other one before - thanks for sharing!
@@SailingTipsCaYou're welcome. BTW, the analogy with the rods is also animated here:
czcams.com/users/shortsH_OKNr120t4
I don’t believe the keel or centerboard contributes anything to forward motion.
The amount it contributes is proportional to how close to the wind you are sailing and in very fast boats you are typically sailing very close to the wind. Have you ever tried sailing close to the wind in a boat with a retractable daggerboard that wasn’t deployed?