An Introduction to the Physics of Sailing
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- Опубліковано 11 лис 2017
- The goal of this lesson is to explain how sailboats work by exploring basic physics principles. At the end of this lesson, students will be able to identify the forces acting on a sailboat and explain how the combination of these forces results in the forward motion of a sailboat. Students should be familiar with vectors and be able to use them to represent forces and moments, and also should be familiar with using free body diagrams to represent forces and moments. A basic understanding of fluid flow and/or resistance might be helpful, but not necessary. This lesson and the follow-on assessment will each take about one hour to complete. Students only need pen/pencil and paper to complete the activities in the lesson, although an optional activity where students make their own sailboats would require additional materials. The classroom activity challenges are centered around small-group discussions based on the questions posed before each break. Free body diagrams, or another conceptual representation of his or her answer, should support each student’s solution to the questions posed in the video. Instructions for the option of having students design their own sailboats as part of this lesson can be found with the Teacher Resources.
Attention: It has been pointed out to us that certain experts disagree with the explanation for the generation of lift presented in this video lesson. For this reason, we would like to refer viewers to the following articles which present an alternative explanation:
www.gentrysailing.com/pdf-theo...
www.northsails.com/sailing/en...
For more information: blossoms.mit.edu/videos/lesson...
Great video! As a novice sailor and a person who HAS to understand how things work in order to remember them, this video is perfect. Thank You!
Great lesson for aspiring engineers and sailors. Will recommend, thanks!
My brother learned to sail on the other side of the river with Community Boating in Boston. The Charles basin is notoriously tricky with its shifty winds! Those Tech Dinghy boats sure look faster than the Cape Cod Mercury ones on the Boston side. Thanks for the explanation!
Thank you 😀 Emma for that videos and illustration with diagram it made it easier for me to understand about sail. 👍👍 it was much more then i anticipated about sailing.
congratulations on this fascinating video on revealing the Black Arts of sailing........trouble is I've never been on a sail boat...but i still want to learn how to sail...
Great job..I was looking around for an explanation like this vs just being out on the water and making sure your tell tails are in the right direction to capture the wind .
aw. i really miss engineering! great explanation. great job!
Thank you so much. As a pilot it was very interesting and enlightening to learn about the principles of the airfoil being applied to sailing. This will go far in my sailing interest. Have a nice day.
Interesting how airfoils have been on boats for millennia, but as airplane wings, not so long.
Nicely explained, but perhaps there was too much emphasis on the lift from wind blowing over the profile shape of the sail in exercise 1. Those lift forces would be very minor compared to the force from the wind directly on the sail surface and countered by the daggerboard, keel and rudder. This is evident through camber-free sails as can be seen in some windsurfers and in the example where you tried to sail without the daggerboard. I am bringing this up as some people believe that the force which allows one to sail upwind is primarily from the profile shape of the sail...which is incorrect.
Exactly what I was searching for. Thanks
Thank you for your explanation. Good to install a small one in my kayak!,,,, for experimental purposes.
Great video. Thanks! Were the Tech Dinghys replaced? It's been a long time since I sailed at MIT. Course III, '81.
This would have been very helpful information to have watched before I tried and failed after buying my first sailboat up in New Jersey, but we live and learn. Keep up the good work thanks.
I just made a sail for my kayak.. I live in Missouri. The only members of my family who’ve sailed were my grandpas to go fight the Japanese. I did use decent research and I’m reasonably intelligent but this video is just further learning on the mechanics of it. I’ve taken her out on a nearby lake a few times with modest success.. BUT I’ve definitely had some butt puckering moments! I made it Viking style as a kayak has no keel.. I sincerely hope your lesson isn’t at the bottom of whatever waterway you undertook 🙏🏻
What fun! I'm thinking about an autonomous RC Sailboat. Fascinating problem! Great guns btw, result of hauling in sheets.
Feed the Geek!
I was curious and anticipated some of the forces&moments that would be in play, but I learned a lot about the centerboard & other aspects, good explanation! Thank you :)
The paper / fan demo is an excellent refutation of the idea that it is differential speed, caused by the curvature of the wing / sail, that creates the upward lift - not the difference in travel distance. Flat wing balsa wood gliders, launched with force by the same kids that hold their hands out of car windows, completes the idea that it's the force and the angle, more than a differential gradient, that affects the climb. One other note: air, being a fluid like any other, has a stickiness that needs to be taken into account. Hint: it's the same as the last drop of honey that climbs back up the string of honey to rejoin the spoon or the honey jar. It's a major force behind the lift you experience with wings and sails.
Thanks for sharing, very useful and helpful.
Thanks for the video Emma!! I really like the visual examples. I will apply someday with my students!!
thank for the lesson... really great explanation....
The stem is the most important design quality of a sailboat design. Ballast the boat and keel the sails.
Great video Emma!
RESPECT = GREAT PRESENTATION
I thought I saw velocity spelled with an s somewhere in the video. At 7:37 I think. Bottom left corner. Thanks for making the video though. It’s helpful.
Lateral resistance ahead of the sail effort is essential. Mast and stem lateral resistance is essential to rudder control and lift.
What is usually missing from sailboat design today is keeling design that has lateral resistance ahead of sail effort. The stem to stern academic keeling design reduces heeling over and increases speed of the sail boat. Most importantly this keeling design keeps the boat easily sailing into the wind and the sailor can easily keep the bow to waves and wind.
This lateral resistance ahead of the sail area is essential to create lift and have greater speed.
The center board should be directly below the mast and ahead of the mass. If you keel the boom the boat heels over before moving forward and has less sail power..
Thanks , very informative video
The stem is halfway between the mast and forestay of the largest sail. This is the point where keeling of the headsails begin and should relative to the sail area ratio of mainsail and headsails.
Great video! Although I think you have the direction of the “keel force” acting the wrong way at 9:53. The keel acts with a similar magnitude force to the sail (around 6% less) but it also rolls the boat leeward. The only moment arm keeping the boat upright is the body weight. That’s why we lift centreboards when it is windy, it depowers the entire system.
Thank you, J3zzaG. We will definitely look into this matter!
What does the B/D ratio have to do with vessel performance?
The fastest direction is across the wind. The apparent wind ahead of the boat ends the speed of the boat.
When it comes to demonstrating the effect of the force created on the profile in a stream, I prefer an ordinary soup spoon with its convex surface close to the stream of running water coming out of the tap. You can see and feel it. No appealing to Bernoulli's law or looking at the wing of a jet-powered airplane.
What do I do with my hands?
good video , you now have 1000 likes:)
The force vector ratio from width of the boats is the trimaran and catamaran design. A catamaran should be built in have a force vector ratio that is three to one. HtoV. The horizontal force you can capture before the boat heels and you lose wind power.
This width is.....67.5 midmast to pontoons for a catamaran. The sailboat design is twice as wide as the boat is tall. Also known as the Cleopatra's barge. The fastest boat design ever conceived and built.
When will not keel the mast and headsails to sail upright and faster? Stem to stern keel line or wing keel and blade keeled head sail. What if you keel the mast accurately at the mast and remove the unkeeled headsail?
Has any one ever seen an experiment proving the hypothesis that air destined to travel over the top of a foil increases its speed when it encounters the leading edge of the foil and begins its longer trip over the top? One could add two pulses of dye into a slip stream so that they travel on either side of a foil. The expected result, according to the explanation of lift in this video, should be the pulses arriving at the trailing edge in exactly the same relation that they arrived at the leading edge despite one pulse having to travel a longer distance. The pulse had to have received a force in the trailing edge direction to increase the speed component of the velocity. What generated the force int he trailing edge direction that increased the speed of the pulse that went the longer distance?
That's why i like youtube
The mast should be keeled and the headsails keeled more deeply between the mast and forestay.
The keeling of the mast at the mast is often missing.
The surge of lift is greater than the power of jamming.
Thank you I'm William Elica & I'm planning to voyage from lat 20° north longitude 121° east. To Sydney , My late father the best friend of American coastguard here in Batanes island Philippines ,Thank you white Americans to give me reference
Have you also investigated regarding LWL over the Hull Speed as yet conceptualising the boatbuilding with short LOD with wide Beam but all of my hull concept obtained semi displacements hull as enough to configurate proper ballasting systems using Gaff Rigs as main sail
as yet I mention a pocket yacht with 16 or 17' LOD under the 20 or 21 LOA
as though I was not properly schooled with degree but technically under the domestic doctrine standards nobody believe me with extra-curricular property especially within these curriculum aren't been part a standard curriculum here, as fell short some degree of misunderstanding enough to call me a delus
So the downwind quarter is the fastest quarters to sail.below 90 degrees to the wind. 2.0 times windspeed is maximum boat speed. But perfection is not a realistic goal. Vesta's speed can be reached in a full size sailboat design of normal academic design. If the keeling design is correct and the width is twice the height of the mast or greater.
Noticed this was some 3yrs ago. I'd love to know what the young lady is doing now.
I know she's right, but my cranium exploded about 6 mins into the video. LOL I should have planned to watch about 2 mins of it a day for 8 days so as to keep that from happening.
this is over any newbie's head
just go find a sailing school and learn hands on
it's too easy to over think sailing
Anyone know the model of dinghy she is sailing?
wow it looks like she is having so much fun! she is definitely not reading anything
Send Free Body Diagrams
On a technical level it’s very interesting. But really, i fell asleep
I always thought yachts more or less got sucked along, not blown along.
Im here because of Atlas lol, still confused
I looked at your eyes the hole time!
Dat gap
Can you slow down please? Maybe telling people what they need to do first and explaining "why" later for people with very little physics experience.
You remind me of Abby from the Last of Us Part 2
All i heard was words. I i kinda get it. Im knowledgeable with planes and helicopters and understand them easily but i just can't grasp sail boats.
Beep boop
Why is that sailboat model so beat up? and its got a wood screw for the front bearing lol
The sailboat can sail up to twice the speed of the wind but this is theoretically perfect number and not physically possible. 1.5 times the windspeed is a realistic goal but without stem to stern academic keeling design this ambition can't be seen.
Yes, she does a great classroom production but it comes across very fast and clinical. Unfortunately people like me who are able to learn complex situations fall asleep in clinical classes.
Oh ..
I dont get it.
Bernoli or whatever air thing is never makes sense
It cant generate enough lift to lift a 300 70kg adults and fuel and avionics right ? .. along with its own weight.
.. the perpendi doesnr make sense
Nerds rule. Nerds make the rules too. : )
They don't teach spelling at MIT.
The keel is in the wrong place. The keel should be at the mast. The following edge of the keel matches the following edge of the mast. This on keeling.
The on keeling should be faster. An experiment should settle the question about speed.
I dont watch sailboat races I participate in them
Going way too fast for so much technical info ...
0
i guess there is no easy way to understand this.
i just wanted to learn about sailing but ended up just staring at the pretty girl the whole time
MIT? Not the right explanation. Dang.
unpopular opinion : very confusing and overstuffed presentation .
Sorry to hear that you have a point of view.i believe all videos have value for someone somewher.i liked it for it's detailed content and can refer back to it when I need to explain how it all works.some of this I learnt in my physics at the age of 13.so when I came across it I could relate to all of it
decent video, but i think you missed the public speaking class....then i fell asleep due to the monotony
Uncalled for, and I disagree. She spoke very clearly and energetically. Her work made a positive contribution to teaching sailing.
@@trackie1957 oh settle down. go find a safe space