Forces acting on the windsurfing sail

This crude animation is meant to explain forces acting on the windsurfing sail. It should help some beginners to avoid typical mistakes in a stronger wind, learn faster, and enjoy windsurfing sooner.
published by www.na-windsurfing.com

[@djstretch2010]

Outstanding! I've been sailing for years and have just started learning to windsurf. This is a very succinct overview of how wind affects a sail. In fact, if you ignore the footstraps and rider position, this applies to any sailing boat, mono or multi-hull. I salute the author on an excellent job well done!

[@cetric26]

went through so many videos trying to understand this concept. You are the first person to clearly explain it. Thanks a lot. Hope you make more

[@marklewis6270]

You'll find a better explanation here: kzbin.info/www/bejne/mZu3k2RrpdKYY8k

[@cetric26]

@@marklewis6270 it was excellent. Thanks a ton

[@wlyounce375]

VERY HELPFUL. All beginners need to hear this. I'm an engineer and even I was able to understand better after this video. GREAT job ! Please keep up the videos.

[@eonang9751]

Finally found the easiest way to understand sailboat physics. Thank you so much

[@vempo]

Great video. in fact, the best out there for beginners to understand the science and practicality of windsurfing. The idea to use a "top-view" to illustrate the wind force is brilliant. Thanks a lot.

[@damianketcham]

Nice video!!! Thanks for taking the time to help the windsurfing community. 👍🏻

[@tristanbach8690]

Dude, this makes so much more sense. Thank you!!

[@johnso4239]

Thanks so much! This clears a lot of confusion for me.

[@valetprivet2232]

best explanation ever

[@thorstenc7342]

Very good explanation 👏🏼👍🏼 I learned a lot for teaching

[@3denlightenment]

@@thorstenc7342 You might also like this one. It correctly explains the physics: kzbin.info/www/bejne/mZu3k2RrpdKYY8k

[@jemand8462]

3:20 the most realistic airplane drawing ever! even with rotating wings! :D

[@christiankentorasmussen7492]

Great explanation about how the sail works

[@bradkubota6968]

I think at some point my sail trim was done mostly subconsciously by me using my ears. Yes, thats right. Looking into the apparent wind results in a balanced wind across both ears. This of course is during powered up conditions at speed. Then your arms sheet in or out accordingly. When sailing with a hoody in cold weather I always felt handicapped with my ears covered. Also you want to keep your mast as vertical as possible to present the largest sail size to the wind. Many people sail with the mast to windward which reduces power. This can be a method though when sailing over powered reducing power. I used this to reverse effect when ice sailing. Using the sail angled away from the wind gave a slight down pressure, useful on glare ice.

[@chreif]

what I have been looking for...do more of this pls. thanx

[@felikno]

Bro finally I understand how this is working...thx so much!!!

[@user-ym5dm9xd5w]

Super useful. Great video. Thabks.

[@massimocataldo954]

Simply great!!!

[@balazsrepasi8035]

Super interesting. Thanks 🙏

[@alsterg]

Finally, an explanation! Thank you

[@franknitschke6199]

indeed, excellent explanation. Was looking for these informations for months!

[@justinbianchi]

Thank you so much for this video it has helped me thrive in my beginners class

[@StephaneFitch]

Awesome explanation! Thank you.

[@charlesarcher9626]

Thanks for the important info..really helped me

[@neosn1232]

Fantastic video. Thank you 2012 dude

[@miles_walker]

A good explanation, thank you.

[@MrFanaticrat]

The apparent wind in windsurf is huge. At the end you always feel you are going upwind.

[@ophthalmol2009]

Great explanation; thanx..

[@samjones3106]

Somethings wrong or missing with this theory. The resulting force will always be downwind. To go upwind there must be a force acting against the drag to counter act it. Also when I look at someone surfing it looks like their sail angle is much more than 18 degrees even when going very slow with little induced wind.

[@salsamancer]

It is possible to sail upwind because the "lift" force is perpendicular to the wind direction. When you are sailing into the wind at an angle this allows you to move into the wind. Also, the wind direction that the sail "experiences" is a combination of the air's movements and the motion of the sail as we are moving through the water, so it's a bit tricky to think about.

[@trentonmatthews1045]

A fantastic explanation

[@TechNewsAndReview101]

Amazing video, very well explained

[@TechNewsAndReview101]

The "Stick and Rudder" of windsurfing :)

[@MartiA1973]

A wind surfing lesson in my kinda language. It wing! Had to sub- thank you.

[@ivefiorentina6]

Very useful and easy to understand

[@alvarovallejos8465]

Thank you very much, I understood lots from this video. What happens (at speed) if you open the sail outside the 18 degrees? (clockwise in your diagram)

[@florinsi]

Great video ... thank you !

[@zytigon]

Thanks, good explanation.

[@binbinxiong3059]

OMG this is aweeeeeesooom huge thanks!

[@sotirissalloumis6129]

Very helpful , thanks for sharing !

[@aerovideos]

thanks for the video ! where is your website please ?

[@jeffpittel6926]

Does forward motion increase apparent wind vs true wind speed allowing a windsurfer to travel faster than the true windspeed? For example an iceboat can travel faster than the true windspeed.

[@marklewis6270]

Yes. See an explanation here: kzbin.info/www/bejne/mZu3k2RrpdKYY8k

[@bradkubota6968]

When I used to ice sail the apparent wind would be stronger than the actual wind. In 20 knots I would rig a 3.4 meters sail. Reason was it would keep accelerating until fear was the limiting factor. A bigger sail would have to much drag at 40 knots and become unruly. The smaller sail would just keep pulling HARDER and harder. Was a total blast. Hit 60 knots numerous times. Total sickness.

[@LuisMartinez-xd4lq]

much better than all those "tutorials" where some guy starts windsurfing and talks and talks and talks and talks without showing any helpful visuals too bad the website is down?

[@candewan6197]

After a while it's all about feeling and muscle memory.

[@tyg6699]

The wind is blowing from right to left, but why the resulting force direction is upper left? Thanks!

[@PlantwithPetra]

yu call it a crude animation? I found it very helpful. Now I understand why I wuz having so much trouble as a beginner. I hav bin pulling past the 18 degree envelop. This is ritten in the new trending Inglish.

[@caniko2]

Awesome video!

[@paulobparaujo]

Nice video!! :)

[@riteskills]

good video, but i woudl appreciate describing the forces with different wind directions

[@tomcatave]

super!!! thank you

[@t.2826]

0:16 Sorobon !

[@nawindsurfing]

What happens (at speed) if you open the sail outside the 18 degrees? You will slow down, until the sail will be back in the 'green' zone. Forcefully pulling you front (mast) arm is called emergency break :-)

[@doge114wo6]

ah ha! Thank you!

[@marklewis7306]

This is interesting...but almost completely wrong. The physics of the airfoil has very little to do with the forward motion of the board which is why you can sail with a cam free sail. The forward motion or motion upwind is a function of the force on the angled sail translated to the daggerboard or fin in the water. The resistance of the lateral movement in the water is provided by the daggerboard and fin which is at angled in the direction of your travel. The force on the sail is translated through your feet which controls the direction of the board. Overall the force on the sail downwind is countered by the force in the water provided by the daggerboard and fin allowing you to cut through the water upwind. The explanation you provided would never explain how the craft sails upwind. To prove all of his explanation is wrong try sailing without the daggerboard or fins.

[@tabou2651]

You seem to know your stuff. Would you mind telling me your sources? I will have to write an essay in the near future and want to write it about the physics of windsurfing. Thank you very much in advance!

[@tonybrandao4681]

I agree with your comment,but I have a question with the dagger board I understand windsurfing can only be at most 60deg to the wind while sailing upwind not 45deg like in a sailboat, why is that?

[@marklewis7306]

@@tonybrandao4681 Hi Tony, I would say that the sailboat may have a bit of an advantage having a daggerboard and a rudder. Also, the size (surface area) of the daggerboard in a typical sailboat is relatively large providing significant resistance to lateral pressure provided by the wind. I would also say that a windsurfer with a daggerboard and a fin can sail pretty close to 45deg; whereas, a windsurfer with just a fin will not be able to sail upwind as well. The lateral resistance provided by the relatively narrow fin makes it difficult to actually sail upwind at a steep angle. A windsurfer with a fin only provides the added maneuverability which is necessary for gybing etc.

[@bobswhatnowchannel8028]

IMHO, his explanation is spot on for a beginner. He could have a part 2 that explains what goes on under the water to react the sail forces, generating forward motion, but "completely wrong?" I totally disagree. I am hoping for part 3 as well to explain steering. As an instructor, I just sent this to all my newbies. I really don't follow your comment about the physics of the airfoil, forward motion, and cam free sails. Whether a cammed sail or not does not affect the basic physics, and forward motion/speed most definitely affects the direction of those forces. My only suggestion for improvement on this one would be to show the forces at the Center of Effort, not at the mast as someone below commented. That would lead into the tutorial about steering.

[@marklewis7306]

@@bobswhatnowchannel8028 Hi Bob, I would send your students to this video kzbin.info/www/bejne/oHvXp3p8bduNmKc. This is explained simply and correctly. The importance of the keel, daggerboard and rudder cannot be over emphasized in providing a balanced force against the pressure provided by the wind. Have your students sail in their boats without those and they will quickly learn why they are essential to sailing upwind and steering. The sail catches the force of the wind, but it is what is under the water which controls the direction.

[@M-art2224]

The physics are wrong on this. Check out this video here: kzbin.info/www/bejne/mZu3k2RrpdKYY8k

[@fadeyda]

man you should explain why the boat does not turn and how fin works. you are applying forces at mast mount point which is also wrong, keep in mind that sail does not have just one mount point, another forces are applied to the boat by means of surfer feet. plus mind that cheap sails has simple shape and unlike plane wing it should not create lift force.

[@LuisMartinez-xd4lq]

this channel had lots of potential too bad it seems discountinued

[@rogelioarosemena7361]

Thanks, great video.