There is one more component that is important for the twist which is not related to depowering. As wind usually flows in a laminar stream there is a difference in wind velocity between the wind a bove the water and wind at the higher hights. This means that you have a lower windspeed at the boom compared to the wind at the top. While your boat speed is the same at bottom and top the components of true and apparent wind and thus wind directions at the bottom and the top of your sail are different. This results in the fact that a twist of your sail will accomodate to the fact that the top has a higher component of true wind. An optimal sail will always need some twist. Otherwise you might argue that for a non-depowered sail with best performance you would want to have no twist at all. But that is not the case.

@ColoradoSailing

11 ай бұрын

That’s correct for light wind sailing. A bit of twist can help you optimize power due to the different speeds and angle of wind at different heights. The leech telltales should be your guide for setting proper twist in light air. In heavy air, the differences in wind speed and direction between the boom and the masthead are less pronounced because the increased power of the wind reduces the effect of friction with the ground or terrain.

That is one of the best explanations I have heard.

@ColoradoSailing

11 ай бұрын

Many thanks! There are many variables that can come into play that I did not cover. But I think the vid is a good basis for understanding and then you just have to go out on the water and experiment!

I would like to suggest that angle of attack is a function of the sheet position and that twist changes the airfoil camber. More camber at light wind is similar to flaps on an aircraft taking off and landing at low speed. As wind increases a flatter airfoil works better until there is just too much power and then twist can be increased to spill lift at the top.

@ColoradoSailing

8 күн бұрын

@@CurtisTheFlyer Not quite. Yes, the mainsheet controls the overall (or gross) angle of attack of the sail because it controls the position of the boom (along with the traveller, if you have one). However, with twist you can adjust the mainsail’s angle of attack along the height of the sail (from foot to head). With little twist (a closed leech) the angles of attack will be more aligned with the boom along the full height of the sail. This will give a narrow steering groove and “power up” your sail in moderate winds. With more twist (an open leech) the angles of attack change along the height of the sail-the top part of the sail is no longer aligned with the boom. This depowers the sail and provides a wider steering groove. An open leech is used both in extremely light airs (to widen the steering groove when winds are so light that it is difficult to properly trim your sail) and in heavy airs (to decrease heeling forces and/or to provide a wider steering groove in choppy seas). Twist, however, does not change the sail’s camber (also referred to as draft or chord depth). This is a common misconception. Draft in the mainsail is adjusted with the outhaul and mast bend (backstay tensioner). The forward/aft position of the draft (draft position) is set with halyard tension or the cunningham. So it is very possible to sail with a tight vang, closed leech, little twist and large draft. Conversely, it is also possible to sail with a loose vang, open leech, lots of twist and a narrow draft. I sail in a lot of heavy airs where my boat is overpowered, so narrow draft (tight outhaul, bent mast, tight halyard) and lots of twist (loose vang) is the way to go. Also keep in mind, the vang controls mainsail twist when reaching and running, but the mainsheet takes over and has more purchase to control twist when the boom is closer to centerline. ⛵️

Thanks a lot for the explanation!!!

Brilliant and clear! I'm building a sail, thus helps a ton!

Thank you so much. I find yours the best explanation of sail twist by far.

@ColoradoSailing

Жыл бұрын

Thank you for the kind words!

Very helpful. When its explained this way it all makes sense.

Twist and shout! Thank you for explaining.

Great explanation on sail twist. Thank you.

Very good explanation, thank you.

Elegant presentation.

That was excellent. Will be working with the Vang more in the future

That was a very good explanation and it really helped to actually see it on the model sailboat

@ColoradoSailing

11 ай бұрын

Many thanks! Both twist and sail trim are topics that many people like to generalize about, but different situations require different tuning. And many “arm chair” sailors out there only sail in optimum conditions…

I found you looking at a P18 and have stayed for the lessons. Very helpful

@ColoradoSailing

11 ай бұрын

Many thanks! I’m only on my 4th season, so I’m just sharing whatever I learn along the way! 😁

Excellent. I agree with others. The best explanation for twist I've come across.

@ColoradoSailing

Жыл бұрын

Thank you! Glad you enjoyed it.

really clear from the very beginning

@ColoradoSailing

11 ай бұрын

Many thanks! Glad you enjoyed it.

Thanks very helpful

Great video thank you

@ColoradoSailing

11 ай бұрын

Many thanks!

Thank you!

nicely done and easy to understand..

@ColoradoSailing

11 ай бұрын

Many thanks!

I am still experimenting with my P18. I’ve had it out 7x since launching May 15th. The boat is a fantastic performer compared to my previous Potter 19 and ComPac 16. I purposely took her out before a gust front came through last week with 1 reef in main and 30% furled Jib on my 10x1.5 mile inland lake. Winds in the gust front to 25Kts and she handled it with no problem close hauled into the wind. I haven’t experimented with twist yet but the vang was pulled tight. I am in the process of figuring out how to make YT videos and have some good footage from my P18 adventures. Next month I’ll take her on a week cruise of the Western Basin Lake Erie islands.

@ColoradoSailing

2 жыл бұрын

That’s awesome. Glad you are enjoying the boat! Look forward to future KZread videos!!

Nice explanation and cool model! This is one of the few things I was smart enough to learn on my own sailing lasers one summer as a kid, rolling the boat over into cold water in high winds was good reinforcement of what works best and what doesn't. Plus, a sail with some twist just looks so graceful.

@ColoradoSailing

2 жыл бұрын

There certainly is an alternative school of thought that says tighten the vang in heavy winds. But I find the heeling and narrow steering groove tedious. Plus, if the boat is pitching about in waves, the wider groove and twist will keep the boat moving better! 😁

@jford1

10 ай бұрын

@@ColoradoSailing Yeah, interesting how a lot of what we were taught as kids was only one way of looking at it. I was always taught to tighten the vang in high winds, but of course depowering the sail with more twist probably leads to more speed (to go with improved stability)!

We should note that the reference for wind speed is 33 feet above the water. The difference in wind speed at the deck and at 33 feet can be as much as 30% faster than on deck.

@ColoradoSailing

11 ай бұрын

True. Good thing most mainsails are a triangle shape with less sail area at the top! Wind speed gradients above the ground also decrease as wind speed increases. Since this short video is more geared to de-powering in heavy wind, I did not cover wind speed gradients.

Model example is actually using the Mainsheet to explain the boom vang. Need to remember that when sheeted in tight going up wind, the boom vang is out of the picture until you ease the mainsheet,

@ColoradoSailing

11 ай бұрын

The model doesn’t have a vang…so I did the best I could to demonstrate the effect. I used a wire twist tie taped to the leech to create the different shapes of the leech in the video… 😁

Than you

Can do do a video how traveler works for twist and how to trim in upwind and downwind conditions?

@ColoradoSailing

10 ай бұрын

Unfortunately, my boat is not equipped with a traveller and I’ve only once sailed a boat equipped with one. I understand the concepts…but don’t have the practical experience. ⛵️

Ive done a spectacular dead roll and it caught on camera 😂

@ColoradoSailing

9 ай бұрын

Wow! Hopefully in a sailing dinghy…and not a big keel boat…😁

great demonstration for a subject that is not very clear in my head.

@ColoradoSailing

10 ай бұрын

It’s just one of those things you have to play with in different wind conditions and get a feel for how adjusting the vang effects the flowing of the leech telltales, drive of the boat, and heeling. ⛵️

What I still don‘t understand precisely: I should ease the kicker to depower the sail by opening the leech. Something that I want to if I’ m overpowered. But easing the kicker also reduces mastbend and therefore leads to more drought in the sail, creating more heeling forces. So by easing the kicker we create two contrary effects. Which one is more important?

@ColoradoSailing

4 ай бұрын

Good point! On my P-18 I added a backstay tensioner that can apply up to 3.75” of mast bend, so the vang is not a factor in mast bend on my particular boat. But many boats lack a backstay tensioner or don’t have a backstay at all. In that case, you should flatten sails as much as possible first (tight outhaul, tighten main halyard, and tighten vang to bend mast) and let the mainsheet out (setting the flat sail like a blade to the wind) when there’s too much heel. If still overpowered, then it’s time to reef (if your boat is equipped). Of course with a shorter reefed sail, mast bend in the top 1/3 of the mast doesn’t help flatten much because the sail isn’t as high on the mast anymore. Finally, I would then loosen the vang if still overpowered. The top of the sail will likely flog, but it will reduce heel and help keep the boat under control (unless deeply downwind where too much twist may induce heeling to windward). You can also try lifting the CB to reduce heel (works on my boat) but you will have more leeway. Definitely something you should experiment with on your boat in different conditions to see what works best. Cheers! ⛵️

@daniellutscher2520

4 ай бұрын

Thank you! Indeed my situation, because I, as you suggest, don‘t have a backstay tensioner.

Nicely don…..

@ColoradoSailing

11 ай бұрын

Many thanks!

None of the examples you provided considered sailing very close to the wind, a situation in which the main can luff due to too much pressure between the Genoa and main. In that case, the luffing can be eliminated and better trim attained by pulling the boom to windward past the centreline of the boat using the mainsail traveller. This allows the boat to sail very close to the wind.

@ColoradoSailing

11 ай бұрын

Well, you are not wrong…but this video is more geared toward heavy air sailing and specifically about depowering with twist. In fact, in very heavy air I often do exactly the opposite of what you suggest-I purposely backwind the luff of the main as a way to depower the mainsail. As far as the traveller, my channel is more geared to smaller trailer sailing boats (with a focus on the Precision 18). Most sailboats under 20ft do not come equipped with travellers.

I understood what you were saying and it is very well explained, but man, that second graph really gives me a slight headache trying to understand it. Anyway, I learned something today. In real life I have the issues with a flapping leech and not sure how to address that yet but I feel it's related.

@ColoradoSailing

10 ай бұрын

If it’s just a rapid flutter in the last inch or 2 of the leech, then you can try tightening your leech line (a thin white string with a plastic cam cleat that hangs near the bottom of the sail’s leech). Pull on this thin line until the fluttering just stops and lock it into the plastic cam. If you pull too much it will curl to windward (not the end of the world if it does…better than the flutter). If it’s a larger part of the sail flapping (flogging) toward the head, then you can try reducing twist (tighten vang). If it’s more than just the head of the sail, then pull in the sail or bear away from the wind to better fill the sail. If it’s more of a bubble in the luff (near the mast) then it might be getting back winded by the headsail. In that case, let out the jib/genoa sheet.

Being a dutchie, the first thing I see is red. white, blue Holland.

@ColoradoSailing

2 күн бұрын

Hup hup!

does this change for a fully battened sail

@ColoradoSailing

11 ай бұрын

It should work the same with full battens. Full battens help the sail cloth maintain a better foil shape which is especially helpful in light air. They also reduce flapping/flogging compared to smaller battens in heavier air. But since they run horizontally, you can still “twist out” a sail with full battens to help reduce heeling and spill some air at the top.

So, what about the angle of attack being different at the head than the foot because of the different wind speeds? Or, does this only matter for light air? Newbie here, trying to figure this all out!

@ColoradoSailing

Жыл бұрын

Wind speeds are lower closer to the ground due to friction (drag) and turbulence caused by interaction with the terrain (and waves) and a wind direction gradient may also exist in winds of less than 6 knots. So in light air, to get the maximum drive force through the whole height of the sail, you may need to add some twist. As the wind increases (moderate winds) you reduce twist to maximize drive and efficiency as your boat starts to “power up” in the breeze. In heavy airs (when the boat is overpowered) you can twist out the top of the sail to depower and reduce heeling. I suspect this is also why many sailboats have a triangular sail, so the sail area is decreased as you go up the mast which helps to balance out the forces on the sail, mast and boat.

@cellobob2358

Жыл бұрын

@@ColoradoSailing Thanks! In our boat we have no vang (yet). Would the best way to increase twist be to pull the traveler to windward? This is the confusing part for me, because I've definitely read that in light winds the traveler should go to windward, and the traveler should move to leeward in heavier.

@ColoradoSailing

Жыл бұрын

@@cellobob2358 The mainsheet controls twist only when the boom is close to centered because of the angle to the sheeting location. The further out the boom is (bigger angle), the less twist is controlled by the mainsheet. This is where the vang comes in-it controls twist when the boom is further out from center. Twist is all about allowing the boom to rise. With a traveler, when the traveler is directly under the boom and the mainsheet is tight, you are tightening the leech (no twist). So to increase twist you would let the mainsheet out and keep the traveler more to windward (to create an angle between the sheeting location and the boom).

@AndyUK-Corrival

Жыл бұрын

Wind shear can be very pronounced and I have used topping lift to increase twist. Also important to use sheet lead on Genoa’s and if needs be a barber hauler.

@spelunkerd

11 ай бұрын

@@ColoradoSailing Gee, this is the opposite of what I thought it would be. I've been adding more twist in light air! Apparent wind is the vector sum of true wind and wind caused by boat velocity. So with higher true wind velocity up top, the apparent wind angle up top is more abeam. In light air the absolute value of the two vectors are closer to being equal, compared to heavy wind where the true wind vector dominates all the way up the mast. So, I reasoned that there would be a more dramatic change in apparent wind angle as you go up the mast in light air. With that expectation of more dramatic change in wind angle going up the mast in light air, I have been trying to optimize sail angle for the whole length of the mast by adding more twist. Wrong?

Opps forgot the most important factor. Airflow is not parallel with boom.

@ColoradoSailing

11 ай бұрын

Correct.

Flattening the sails makes them super sensitive to the hobby horse action. Twisting off the top works way better. This is all exactly correct, many people do it backwards. Two time main trimmer in J/105 North Americans.

@ColoradoSailing

11 ай бұрын

Thanks!! Much appreciated!

@yangyang3175

11 ай бұрын

here in SF bay it's always too breezy (around 25knots), so I'm looking for ways to depower. as noted there are 2 ways, twist or flat. they seem to be setting the vang in completely opposite directions. I never got the flat method working as promised for me: I tighten the vang, my outhaul is always tightened, main halyard is tightened. then I set the traveller way down so the main catches little wind. But in order to depower enough, I really had to set the traveller so low that the whole main starts to flog heavily, damaging the sail. I suppose there is only so much you can depower using the flat method. but under the same conditions, the twist method works much better, I pull the traveller to upwind position, about 1/3 to 1/2 over center, so the leech of main is always pulled tight, and it does not luff.

Bad theory on KZread keeps me in front of the pack.

@ColoradoSailing

11 ай бұрын

Sounds like you’re a racer? This video is about how to de-power an overpowered mainsail and reduce excessive heeling in heavy winds by employing twist to make the sail inefficient. It’s not about how to sail fast. As stated in the presentation, a sail with little twist and a closed leech is a fully-powered, efficient sail (fast).

Lift is overrated.

@ColoradoSailing

8 ай бұрын

Certainly when the boat is overpowered. This video is geared toward heavy wind sailing when you need to reduce power in the sails. 😁

So much misinformation here. The sail induces a lower angle of attack as you move towards the tip. In other words a sail without geometric twist has different angle of attack along its length.

@ColoradoSailing

11 ай бұрын

A sail without twist would only have different angles of attack to the wind if the wind direction gradient were very pronounced at different heights above the water’s surface, as when sailing in very light air. This video is specific to sail trim and twist in heavy air sailing. In heavy air, the effect of friction with the surface that normally causes gradients in wind speed and direction along the length of the mast are virtually eliminated. This is because the more powerful wind is easily able to overcome the friction along the surface. In winds over 6 knots, both the wind speed gradient and the wind direction gradient (often referred to as “wind shear” by sailors) becomes negligible along the length of a sailboat’s mast. So a sail with little twist in heavy airs is a fully powered up sail, whereas a sail with more twist would be depowered and inefficient due to the varying angles of attack along the vertical plane to the uniform wind direction along the length of the mast.

@danielcockerspaniel

11 ай бұрын

@@ColoradoSailing you don’t understand induced velocity.

@ColoradoSailing

11 ай бұрын

@@danielcockerspaniel Well, your comments are short, vague generalizations lacking explanation or argument. I hold a B.S. from Embry-Riddle Aeronautical University and 2 masters degrees. So…let’s have a discussion about induced velocity of an airfoil as it applies to twist in a sail in heavy airs.

@danielcockerspaniel

11 ай бұрын

@@ColoradoSailing A sail is a lifting wing and the 3-dimensional flow about a finite wing induces a downwash at the sail leading edge which increases approaching the tip. I kept my comments brief to allow you to do your own research into the subject.

@ColoradoSailing

11 ай бұрын

@@danielcockerspaniel You seem to be assuming a perfectly set sail. Granted, the vast majority of discussion on sail trim is about optimizing the lift and driving force of sails. However, my video is a discussion of how to use twist to de-power the mainsail and reduce heeling. In this specific case, twist is used to purposely make the shape of the sail inefficient. When there is an over abundance of wind and the boat becomes overpowered, it becomes more about keeping the boat under control and on her feet-and less about maximizing driving force along the full height of the mast. The downwash of a foil is directly proportional to lift. When the sail is twisted out to the extreme, the top 1/3 of the sail is essentially flogging, no longer maintaining an airfoil shape, and no longer producing any lift (nor downwash). Whereas the foot of the sail is likely stalled at this point due to the extreme angle of attack. Lift at the foot is thus greatly reduced. In this “twisted out” condition, the remaining driving force of the sail is provided by the middle section of the sail. It’s surprisingly adequate due to the over abundance of wind. With all the different ways to manipulate sail shape, it’s dangerous to apply generalizations. I most often sail in this twisted out condition with a double-reefed mainsail in 25-30 mph of wind and it works quite well at keeping the boat on her feet while still achieving full hull speed (albeit my sail cloth takes a beating).

Too theoretical👎 controlling the main only by the sheet??? Every boat nowadays has a *vang* and/or a traveller. There's also the backstay, and don't forget the cunningham! Also, the effect of twist is alleviated by higher windspeed higher up. Sorry, but you painted an unrealistic picture.

@theplinkerslodge6361

11 ай бұрын

I think there could have been a better way to make your points known - I always say, "Make your own D*(@ video if you know so much." You're just a punk.

@ColoradoSailing

11 ай бұрын

I guess it depends on your perspective. Like many small (less than 19’) trailer sailers, the Precision 18 has no traveler, does not come standard with a backstay adjuster, does not have a cunningham, and comes with only a single reef in the mainsail. The P-18 is the largest boat I’ve sailed and my channel is very much geared toward new sailors of small trailerable sailboats.

@jwwebnaut7045

11 ай бұрын

@@ColoradoSailing But the P18 does have a vang, doesn't it?

@ColoradoSailing

11 ай бұрын

@@jwwebnaut7045 Yes, the P-18 has a vang. The toy boat I used to demonstrate does not.