Mainsail control: A better way

[@thamiordragonheart8682]

As a Senior in aerospace engineering at Purdue, I don't think the separated skins at the bottom of the leech is as draggy as it looks. With a shape like that, as long as the flow has enough energy, you get a stable recirculation zone behind the flat end that acts like a virtual tapering extension. If there's a little flow through the flat end into the recirculation zone, that reduces the drag even more, and engineering the sail to have that little bit of internal flow should be pretty trivial. if it's hard to believe that it works, look up "truck boat tail", which isn't that different aerodynamically. It's just not as much of a drag difference as it looks and your system loses the 3D sheeting that the current mainsail systems have, which I think ends up being a much bigger deal because of the range of apparent wind speeds the sails have to operate under. Being able to change the depth of the sail, and therefore its lift/drag ratio, as you accelerate is really critical for being able to take off and continue accelerating through the whole speed range with a fixed righting moment. On the other hand, the fact that you found a way to get 2D sheeting for a deck-sweeping sail without cutting a slot in the deck or putting anything inside the sail seems like a great solution for jib sheeting. it would certainly give more control than a traditional self-tacking jib without the mechanical and aerodynamic mess of going to INEOS' 3D sheeting system. You also wouldn't have as much of a friction problem because the jib sheet loads are much lower than for the main.

[@kylestoneham6931]

We tried this mainsheet concept on the Vampire project in 2018 when changing to a decksweeper. Traveller moves fine but the loads on the lead in and side blocks were way too high. There needed to be a 5:1 purchase at the end of the system (traveller to clew) for it to work but the issue then became a lack of range.

[@MozzySails]

was that with the curved boom too?

[@kylestoneham6931]

@@MozzySails yes curved boom with gooseneck just below clew height to reduce compression, sheet angled aft by a few degrees so boom can hold mast rotation out.

[@kylestoneham6931]

The mainsheet system we have is still flawed so open to ideas on how to improve it.

[@wlrottge]

​​@@kylestoneham6931😮hen I sailed with William, the fine side was something like 27:1, lol. I think you're going to have a hard time getting that much purchase and maintaining enough travel. I'm running the GP mainsheet system on my N20C/FCS and you can tell that it has a lot less friction. Possibly use that with a different reeving and some of the new zircon blocks for your cascade to get lower friction (not trying throw shade on Allen, they make GREAT stuff!!)

[@drhaxzaw6523]

Perhaps something else to think of is that each of those turning points are going to be adding structural loads through the hull requiring a heavier hull or strength where the teams want to avoid putting it.

[@charlestoast4051]

But most of the diverter pulleys are in line with the traveler track, so it might be possible for that to take some of the loads.

[@charlestoast4051]

It's reminds me of the rope system used on tower cranes. Large forces on the blocks, but maybe no-expense-spared carbon can take it, and teams might have access to super blocks.

[@barbaraicyda5107]

love your set-up

[@paulgush]

Looks slick, but How would you control outhaul tension and draft in the sail? Among others, Kenny Reid of North Sails was impressed by how quickly and dramatically ETNZ was able to flatten their main once they got up on the foil

[@rexmick]

Outhaul tension is controlled by the hydraulics between the sail. Move the mainsheet fixing point forward in the sail= flatter foot, move the mainsheet fixing point aft= fuller foot.

[@paulgush]

​@@rexmick 2:12

[@rexmick]

@@paulgush Yep, he got the mainsheet control below deck, outhaul control will still be between the sails.

[@MozzySails]

Exactly as rexmick says

[@fredtatch1572]

I like your plan and with the forces involved on the sail it seems unlikely friction from the ball bearing pulleys would be an issue. Good thinking!

[@thegibbonisreal]

Mainsheet loads are in the magnitude of Tonnes.

[@charlestoast4051]

I think most of the friction comes from the line rather than the pulley bearings. The line deforms as it passes over the pulley and is also wedged between the sides of the pulley.

[@Rainman...]

Dude I have never sailed I have only been on a sailboat one time and I absolutely love your channel! Though I live near Annapolis, Maryland, USA which is home to the US naval academy🤔 Please apply for American Magic's social media director... They desperately need you they haven't updated their channel since they got knocked out of the last America's cup 😬

[@MozzySails]

That's great to hear! Although I don't think I will be moving to Pensacola anytime soon (although I understand Magic are soon to move to Barcelona)

[@Rainman...]

@@MozzySails American Magic are looking really good, still my main worry is who is their aerodynamic technical partner

[@alexanderkutschera149]

Couldn't help seeing that elegant trophy sitting on your work bench! Looking forward to your next posting!

[@deano41.123]

Great work. Thanks 👍

[@MozzySails]

Cheers deano

[@davidbalkwill612]

I love your approach to the whole design area. Keep at it, we enjoy your thought process and communication skills. Any idea what the tension on the leach and therefore mainsheet is ? Their direct hydraulic approach can work with very high loads. What would be the limit for yours ?

[@Gefionius]

Looks great! I am hoping a team member or past team member will jump in and comment.

[@ArchieMassey]

I’d designed the equivalent, but with two improvements: 1. A 14 jib style clew, so foot and leach tension can be adjusted. 2. Copying a 2D plotter, the sheet and traveller can be adjusted with just 2 rams. The downside to all this is friction when adjusting traveller constantly. There is only limited peddle power. So the pistons must be placed like the US system on the deck attached to the traveller car.

[@tristankiddie1710]

Hey Mozzie. Great video and great modeling to help people understand. I think the concept would be, if they haven't already, one that the teams will seriously consider. But they will also likely have equations to work out the resistance of the turning blocks involved, which I certainly do not have.

[@MozzySails]

It depends on block and load, but a conservative rule of thumb is 10% per 180 turn around a sheave. So, 30% as set up here for a mainsheet and 20% added to traveller running. With high performance blocks that's likely less... it would be interesting to actually measure though

[@steventomlinson8368]

Your system looks smooth 👌

[@cliveengel5744]

Nice Mossy

[@davidwilkinson9792]

Such a nerd. Awesome. Thank you x

[@MozzySails]

Glad you enjoyed it!

[@floodo1]

There’s also the structural considerations of transferring the load around. Hard to say if it would be better or worse in practice hehe

[@weatheranddarkness]

Thinking of this in this way reminds me of 3 spring setups for high performance car suspension.

[@joepbronneberg3057]

Woo excellent thinking! Be careful now ask for a patent and or you might get hired by a team🧐. I love the idea with the fixed hydraulics, straight rail and simple as it is, aero too. Below deck it will not be vulnerable. Great video with the unboxing and detail shots and the workload!

[@trevorgissing1208]

Well thought out Mozzy. My only concern is that every time you add another piece to the system, it’s potentially another thing to break or fail in some way. No doubt the bogging will be going over your idea with a magnifying glass. 👍👍

[@rbpt__4136]

I think friction could be reduced with a curved rail as it would allow the traveller to move without the mainsheet system friction adding on.

[@quantumvortex3942]

Even with the friction trade off I think the systems gains would still outweigh the deficit, especially having the potential to mount the hydraulics in a more optimal location for center of gravity/mass etc.

[@jamesaron1967]

That's what I was thinking. Just to improve the location of the hydraulics which in turn will also result in superior sail shape makes it worth attempting.

[@oikkuoek]

Interesting design. Although both friction and tolerance in steering are very high on this one. This could work on smaller boat, like foiling moth, but anything bigger brings so much stress to the system, that it becomes fragile and sticky. On modern AC's the main sail is actually a wing, and the back end point is basically holding the stern in the air through this air foil. So, the steering system needs to hold 4-6 tons of mass in the air, while keeping the movement smooth and precise.

[@kristianmartincic3011]

Great video; other worry here is going to be line size and stretch. The loads they're running are going to require some very low stretch cordage, which probably means big, which means big blocks. Interesting tradeoffs.

[@MozzySails]

Yes, true!

[@beerbuffet1222]

Brilliant🍺🍻🔥

[@beerbuffet1222]

Brilliant🍻🍺

[@joaquins90]

I like that idea! Friction could be reduced quite a bit if the line from the Traveller to the hydraulics would go directly as in a self tacking jib. Only one block on the traveller and maybe a second one so the ram is stationary in front of that block. That line could go under the deck if there's open space (as it is with the ram under the deck, but much smaller moving parts) or on top and add a new turning point to go under the deck to the ram. Neither of those blocks add any friction to the traveller movement, only to the ram that shouldn't be a huge problem. And in any case, I'm sure moving all those rams with the sails isn't free either. The only additional friction would come from the added tension to the traveller, probably it would end with the traveller angle lower down. Nice how you made that traveller line work this time around, makes so much more sense now! Isn't a way to operate the traveller from a single ram? Is any reason to need it to go past the center line so two independent controls are needed? I'm sure leaving the weight of one of those on the shore must be a positive thing!

[@rexmick]

They bring the traveller up well to windward, so needs independent controls for either side.

[@joepbronneberg3057]

Oh yes and for the friction. I suppose one could use different rollers and bearings. Like needle bearings. I think this will be seriously considered!

[@alanshearing7515]

Watching your demo I did notice that as you tensioned the main sheet pressure caused your board to pull up. So I believe in full scale the friction produced would be too much . So I guess the sequence of events is the key . Release ,move tension. Not sure if tension on main sail must be consistent when being moved .

[@samgeary1916]

there's got to be a few tones of pressure on the clue of the sail, ropes and blocks would have to he very heavy and expensive

[@jordanspencer5096]

Looks like a self tacking jib system. If you change the setup and fix one end of you mainsheet system and have a single pull back to a cleat rather than joining it together in the centre like you have and then pulling with another control line, you will halve the load, reduce the friction and be able to trim twice as accurately.

[@MozzySails]

Most self tacking jibs on dinghies have the sheet going straight from the car forward to the bow, but I've seen a yachts with jib tracks like this (although not self tacking). I deliberately kept it 1:1 to match the 1:1 they have for current setups, but you're right, fixing on end.would make it 2:1

[@jordanspencer5096]

@@MozzySails you are right mate, most self tacking jibs do have a line that goes forward as you say, but for that system to work you need a perfect radius on the jib track otherwise the car will hang in spots on the track. When I build a self tacking jib I do it exactly as you have done in this video, but fixed on one side and a control line on the other, removes all the hanging issues with the track.

[@Robinlarsson83]

Maybe I'm missing something, but atleast the sheet part of this system is really just a standard big-boat style 2:1 sheet. The difference is really only that the turning blocks at the end of the track leads the sheet back into the center of the boat to an extra turning block, so both ends of the sheet can be connected to the hydraulic ram, turning the sheet to a 1:1 system. On normal yachts that use this style of sheeting, the sheet is either led to a winch each side of the track (90 degree turns instead of 180), or one end is tied of at the end of the track and the other end is lead to a centrally mounted mainsheet winch. Both of those systems are then 2:1 purchase. It's a fairly common setup on larger racing boats, I think the VO65s use it for example. And yes, friction is the problem, with the added friction on the traveller system. A German mainsheet setup solves the friction on the traveller, but that does of course require a boom.

[@MozzySails]

You're right. And I've also see it used on jib sheets with the car moving fore-aft to alter sheeting angle... nothing is ever new!

[@markjk7297]

Very clever, just the friction issue and I assume whether this requires a bigger ram and more energy to move.

[@DumfriesDik]

Genius. Let us know when you get a phone call. Have you put a patent on it?!

[@jasonpickens9839]

Great video. Loved how you setup the problem with clear goals and then pros and cons of the solution. Do you think you could have two smaller rams on the sides rather than one big central one?

[@weatheranddarkness]

for the mainsheet you mean? The traveller is here I think setup like the ineos one with two rams on the sides.

[@petertelford5338]

No idea on this as I know too little to make any sensible contribution. Many comments have valuable pieces of information. I am thrown back onto general principles such as "the enemy of the good is the search for perfection" and "if it ain't broke, don't (try) to fix it" and " keep it simple, stupid" (although I am not even remotely saying anyone here is stupid. From first principles is there a correct assumption that there is a fault worth "fixing" and is there not also an assumption that it is so large a problem that it needs a big fix? And then further, is there enough time to do it in such a way that it does not create other problems which may well ultimately be worse?

[@listeningto8371]

Mozzy. You, like many seem to think a boats looks are as important as it's function.Ref your comment about team NZ having hydraulics between the sheets. The result of the next Americas cup will be entirely dependant on the function of the boat, nothing to do with how it would look on a cat walk.

[@andycarter95]

Interesting, where exactly wait run/ blocks be mounted? You’re initial graphic showcase crew member running forward having come round the clew and they would not want to have rope to negotiate or windage issues. Or would it fit exactly along the existing traveler without catching on anything?

[@MozzySails]

I drawn them somyou can see. But my idea would be to place below deck with just the lines coming up through a slot to the clew of the main

[@Masus04]

Is there any possibility for this to get slack in the system? If so, I could see that being a potential hazard with additional lines running along the traveler that might be tangled in the rollers or on other components. Otherwise this looks like an elegant solution👍

[@MozzySails]

There could be. But it would be house below deck except the line coming up from traveller car the mainsail clew

[@rogiermeijerink1633]

You’ll have to trim/distribute sheeting force over foot and leech (e.g, adjust sheeting angle) over each of the mainsail skins. You could attach both dews to a traveller. Anny mechanical system would require a (of 4 actually) turning block at the tack so requires a boom (aft trim will be counteracted by forward force on trimline). Alternately you could double your sheeting apparatus (i.e., add a downhaul) to each of the mainsail skins (4 travellers on deck?) For this trim I don’t see a realistic alternative for a hydraulic system between the mainsail skins

[@davidwilkinson9792]

Would the hydraulic system fit in the skeg?

[@MozzySails]

Yes, you could run it anywhere, but low down would make a lot of sense

[@Gottenhimfella]

I'm guessing the turning blocks on the traveller would add too much friction (and would have to be rather large) at these very high loads. Unlike with a boom, there is no kicker to help share the leech tension. My main reason for thinking that is the fact that the teams would have been very reluctant to introduce hydraulic cylinders in such an inconvenient, risky and consequential location, and so I'm sure they would have considered and discarded what is a well known way to rig a mainsheet. As I'm sure Mozzy will be aware a German Admirals Cup team showed up with it (in maybe the late 1970s or early 1980s?) and it became known as German sheeting. More typically the tails are led along the boom rather than on deck but the essential principal is the same, just inverted, and that has also often been done on sailing boats of all sizes.

[@MozzySails]

I didn't actually know that. Do yiu jave any link to the german system, I'd love to see

[@MozzySails]

Hey @gottenhimfella, perhaps it's filtering them out as spam if they include links outside of youtube? (p.s. I got a notification you had replied (which contains your reply saying your previous replies have been removed, but now as I come to the thread I can see that reply has to been deleted!)

[@Gottenhimfella]

@@MozzySails Some of the replies which have got deleted did not contain any links. Seems like a glitch.

[@bostonleightalo8729]

I'll take winning over pretty any day

[@Zickafoose2024]

Hmmm what is allen? 🤔😜

[@paulgush]

Allen Brothers make blocks and sailboat hardware. Based somewhere in England

[@lovropirkl2672]

I don't want to be rude, but this system is nothing revolutionary. There are cruising catamarans that have this mainsheet traveller system (example would be Nautitech Bavaria). The teams are probably not using it for a reason, and I'm pretty sure it's because of friction, or the extreme loads that would be in that mainsheet.

[@MozzySails]

It's not rude. I am certainly not passing this off as an 'invention'. There isn't much new that can be done with pulley configurations. But you can say that for most mechanical engineering. The trick is selecting the right solution. The video is about highlighting what I think are some of the limitations of what were the best systems of the last cup and posing a solution. Clearly American Magic and Luna Rossa believe that removing the vertical mainsheet ram from between the sail skins is a potential gain as both have been making changes to this effect. See here: kzbin.info/www/bejne/j32lo2mij9iIjqM As I say in my own critique of my solution, friction will be a problem. However, there are examples of hydraulic mainsheets which have more turning points (such as the caraboni magic sheet). In terms of total load that won't be an issue with the strength of ropes and fittings. The limiting factor is probably efficiency at a given load, mindful that these are powered my cyclors, whereas most superyachts have hydraulics powered off batteries or generators.

[@ChrisCanMakeStuff]

Hmm you might need to stop doing things like this or the videos will suddenly stop after you get employed by a cup team.