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Fastest Mainsails for Overlapping Headsail Driven / High Aspect Main Boats - speed bubble?


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Pics preferred but not required.  What have people found is best for boats that regularly sail with overlapping headsails?  

Rounded main with lots of shape for other points of sail - live with the bubble upwind - or flat main that minimizes backwinding upwind and relies on the kite or jib to power the boat up enough downwind / reaching?

Think 70s / 80s keelboats.  Boats like this have stiff masts that are not very tunable to adjust main draft.

 

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I am getting new Elliot/Pattison sails for my 1979 IOR Ranger Mini-ton.  They made the original Dacron ones so it will be. fun to see the new Dacs.

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2 hours ago, Lost in Translation said:

Pics preferred but not required.  What have people found is best for boats that regularly sail with overlapping headsails?  

Rounded main with lots of shape for other points of sail - live with the bubble upwind - or flat main that minimizes backwinding upwind and relies on the kite or jib to power the boat up enough downwind / reaching?

Think 70s / 80s keelboats.  Boats like this have stiff masts that are not very tunable to adjust main draft.

 

A powerful, easy (hah!) to adjust outhaul & cunningham.

I'd go with a very flat mainsail and opt to let the outhaul go off the wind to get the draft you seek. A baggy main upwind = less point and getting pitched over on your ear in gusts.

We used to run a 140 which caused a speed bubble due to backwinding, but a tapered mast & flat main allowed us to keep the boom pretty high towards centerline & avoid too much backwind w/o adding to the heeling moment too much.

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15 hours ago, Lost in Translation said:

Pics preferred but not required.  What have people found is best for boats that regularly sail with overlapping headsails?  

Rounded main with lots of shape for other points of sail - live with the bubble upwind - or flat main that minimizes backwinding upwind and relies on the kite or jib to power the boat up enough downwind / reaching?

Think 70s / 80s keelboats.  Boats like this have stiff masts that are not very tunable to adjust main draft.

 

I have a 73 Ranger with overlapping sails. A moderately deep main works best on our boat. A flat main really hurts in anything under about 12 true.

0.jpeg

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32 minutes ago, JPD said:

I have a 73 Ranger with overlapping sails. A moderately deep main works best on our boat. A flat main really hurts in anything under about 12 true.

0.jpeg

That thing is a weapon in YRALIS PHRF!

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5 minutes ago, Grizz said:

That thing is a weapon in YRALIS PHRF!

This is true lol. Always 1,2, or 3 unless we did something dumb. Not exactly a J35, but a really nice sailing all around boat.

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Thanks for that. She's been pretty much restored from the keel up in the 34 years since I bought her.

 I keep the traveler up and that keeps the front of the main out of the way.  The mast  on these boats is not exactly bendy. I flatten the main with the usual controls.....halyard, outhaul and cunningham. 

I would absolutely not go with a flat main in the conditions you describe. 

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2 hours ago, JPD said:

I have a 73 Ranger with overlapping sails. A moderately deep main works best on our boat. A flat main really hurts in anything under about 12 true.

 

I'm curious as to why that works for your boat. Could you explain (readers digest version) what you think is going on with the sails, rig, sheeting angles, point & overall VMG to make that setup work for you? 

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Not too sure where my main ranks in terms of full vs. flat but here's full & flat photos taken ~30 minutes apart. Outhaul, Cunningham, Babystay, and Backstay cranked to flatten but the two top battens weren't adjusted.

6daJIdYIFW_FA_hhUvrG-V-19f7YY6fAbwf9bXfpnXX2TJFvhx95YZsHq02aTrEKFy8YqmtR-luxjhHoEXNuWpBqfymrov1_8QnBmfFnboFY2H40V4hnMv2DO-PCzGgka063odrb-ssNyrPVCNrW0oJW4UrOgwiD61DqGMh0FouLEla97YI1JWdzTtPLf9l0LFF9YFLq1k3fYsAPaZYBCEefQmM78B0rv8iDbRQHc9iuZeS4BkfvArHtRw_zxfccA2bNtx00F7DQLihRtHgrniuhR4Rf6nCfrX8yV2-F4zmASgYtuAIO9GAoizUWbRzUldhHjI36BKbzeEpxX_9Pd4Ul6p8-1Iv5i8D9p9H8yOs2-ODnAIVFCjNzBlAO7IYcs-PUiBQ7wRZz0joPCnSwkMGhiuT7lWeknQDmN_HpSHPj3hCb35CCXxFYH2R9RReFbI7xT_S7tpXGOsje3znsMLqNTVAJ4YfJ05x73DE7TJZB49wwxO5Ktqq0dO0l-9qr4iH5zIR3Lsej3zZJAPX6LCuqDOMeFdK6gojIIcFz14xLBZkfyOai6RJdVVwigUauCULiC3srt0mIQmaR0uWWBuJ8c0JUCxFAh-qEKBebxodeyA0TFD7fGqIv_50dIBY0mB0Wc2LJpLuza8gkp1YtfeL0ip4hZFSio0RyPx3rLFvEDkovBtCGNxFnaH7Qtt4xdSDCFhPN5JeoqsvrPUBok3sQ=w1345-h1009-no?authuser=0

pFvwDOZnRmPEb-pa7czE2KkaT_hF1vl3YatyAbyUCe4q8pp-Lu9tncWhsRB0VBr8OZhj4XIEutzL9vFOus72_p-pZOzaAQyWPEeJlhXg-kM6qyd1JNhHSt0qBpiNYH_mQtdWJ9hk7ny4ao9-_3yIkFv4Twv-EwhGlthTO6J05Vg22cRwEV7ac10os9CbgACmJF_Zjtp8dHD6P1eo72HGA5e_VyZFGHCz_PmZcPlPeW4lT2PwCJdq50fIUSrj7PFiv-6FcO4MmQT6kZMErfrU-WpP437CCv37L1Xr0bYxnZtfr_KqSRF88msn1RqT5MqBWy4wMLK_u9FyWFZvW-PuoBSlsvoFY2PqEdUOgRIY7IpK5FTm_tUFpDURls0-jb0yky7DIbUXFGfcDNdzuSSkBOSMvsnQVz2aR8NSQw7Gr8cYOgFQT6E4g2R-itA2Kn7tpL2U6YaGOsg0RXrMa89X2_JiRWcHAJKSkVX8-4MujvsNF8nAtk4vWJiifzmatgyFuGeiBdm1lIBy_j3s-QDhup4hVdfANY_Y28nw3uBFtUkU63r_hQ0jXCTu9ReuPgNStKAT1Zxuvk0xDYAu9nHPR0Z7aeQ_t1c3Y-Q8jvlqofrunpJ4KV0lGdO_3BPZ84qISDzfnuMH_y-VSqINdzYB_A3NBqUbHQ3mdSpDSVoan6PLuwsCMaZJS7ebFjwFaWmmX6UqdPYkZRTlEnkUXKtS5apT=w1345-h1009-no?authuser=0

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Some people may go insane over what I have to offer here.

Backwinding isn't always a bad thing.

It's ugly and has a bit of drag but its not the part of the sail plan doing anything very useful.

The luff of the jib is doing the most work in the whole sail plan and everything after that is just trying to hang onto flow. If you have a big overlap you just have an oversized slot which is there to accelerate flow on the lee of the main behind the end of the slot and help keep flow stuck to that part of the total sail plan. The bubble in the main is just the sail trying to get out of it's own way in the slot.

Downwind, is your main doing anything useful? Does it actually have flow over it or are you doing W/L courses sailing deep and relying on your pretty sail up front with the main there as a billboard? If so, I'd just go with a flatter main. If you are doing a bunch of reaching or VMG sailing and your main actually has flow downhill, I'd be inclined to get something with some more depth and then use the tools you do have to flatten it out going upwind.

Note, I grew up racing 8 Meters with massively overlapping headsails and constantly backwinded mains with fairly narrow sheeting angles. I moved on to sailing boats with wings where we control the slot to the millimeter. What did I learn? SLOT IS EVERYTHING and the individual sails don't matter, only how the sail plan works as a whole matters, just consider it as one aerofoil with a slot in it like a big plane with flaps down at takeoff. Goal is to bend air as much as you need or dare matched to heeling moment for the lowest drag you can get. To bend air a long way you need it stuck to the lee side of the foil (Main and Jib) from front to back without it detaching. The slot injects additional energy into the boundary layer which keeps the flow stuck to the main to the end of the leech without stagnation. That's the goal.

 

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Responses from excellent folks so far, thanks. @climenuts, I can't see the pics you have attached.  Just large white space with a question mark.  Would very much like to check out.

@blunted I've been thinking slot is everything too and that kind of thinking is what is pushing me to go very flat on the next main even for the light air lake I sail on but I know got a ribbon main on this boat with main sail foot under 12 feet and jib often with a foot of 24 feet on a J dimension of 15 feet.  My other boat is an A-Class catamaran and adjusting the mast rotation and other controls to keep flow on the leeward side of the main is the most important aspect of the sail performance.  I've gotten comfortable thinking of the jib and main working together on the big boat and understand there can be circulation between the two as well.  

I never see people really worrying about backwinded mains which seems counterintuitive but maybe this is because it only really happens when the boat is getting overpowered?

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1 hour ago, Lost in Translation said:

Responses from excellent folks so far, thanks. @climenuts, I can't see the pics you have attached.  Just large white space with a question mark.  Would very much like to check out.

@blunted I've been thinking slot is everything too and that kind of thinking is what is pushing me to go very flat on the next main even for the light air lake I sail on but I know got a ribbon main on this boat with main sail foot under 12 feet and jib often with a foot of 24 feet on a J dimension of 15 feet.  My other boat is an A-Class catamaran and adjusting the mast rotation and other controls to keep flow on the leeward side of the main is the most important aspect of the sail performance.  I've gotten comfortable thinking of the jib and main working together on the big boat and understand there can be circulation between the two as well.  

I never see people really worrying about backwinded mains which seems counterintuitive but maybe this is because it only really happens when the boat is getting overpowered?

We get the speed bubble with either of our big headsails, and I pretty much ignore it and focus on making sure the jib leech is breaking even, and match my main leech to that. The main leech is a little flatter of course as I've got more mechanical advantage there but I don't mind a little twist if needed, which means boom might even be a tad above centerline. If I've got too much twist, the bubble shows up, but then i know I have too much twist.

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On the last IOR that we raced (won KWRW 03) with it, a Farr Dickerson 37. We used an outboard track and a flat main. Set the backstay to the average wind speed, then dump traveler and then the mainsheet. Pretty easy upwind really, it liked the slot.

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2 hours ago, blunted said:

.....SLOT IS EVERYTHING and the individual sails don't matter, only how the sail plan works as a whole matters.......

 

This is so, so true even on those new-fangled boats with 100% jibs. On a J/105, you want your jib leach tell-tales always streaming so that you can deliver more wind to your main.

 

Look at those F-1 cars with those 5 bladed front foils. If the rules required them to keep the same surface area but make them solid, you would get 1/10 the aggregate downforce .

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2 hours ago, Lost in Translation said:

Responses from excellent folks so far, thanks. @climenuts, I can't see the pics you have attached.  Just large white space with a question mark.  Would very much like to check out.

 

Flat Mainsail.jpg

Intermediate Mainsail.jpg

Full Mainsail.jpg

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4 hours ago, Parma said:

I'm curious as to why that works for your boat. Could you explain (readers digest version) what you think is going on with the sails, rig, sheeting angles, point & overall VMG to make that setup work for you? 

The rig is pretty inflexible so thats a starting point . I'm  left trimming sails to make a difference and the boat seems especially sensitive to main trim. I prefer to sail with a smaller jib with less overlap...say about 140 lp, and a moderately deep main. This seems to be a good compromise on our boat. I would much rather work on flattening out vs. not being able to power up no matter what because the sail is flat. Years ago I had that type of main which was fine  above a certain tws  but the  boat just won't have the same drive in light air. VMG aside, I know the flatter sail kills us under 8 - 10 true.

On the other hand, if I raced in a venue with 15+ all day I would probably want a sail with less depth. 

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Whatever keeps your helm balanced. Depower as much as possible until the main is providing nothing, then do a sail change.  There is a point that you're just dragging it through the air, which is slow. I often see people trimming their mainsails to look pretty, like in the sail trim books, at the expense of too much heel and helm.  As a rule of thumb, that's also very slow.  Don't over think it, just pay attention to your helm and respond accordingly.

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Yes, they are good photos.  Thank you @climenuts.   @JPD, so you have chosen not to run a 150 or 155 and instead use a smaller overlapping headsail in light air?  Or move to the 140 as a number 2 in light / medium?

It's interesting the compromise the main lives with on a keelboat with a fairly large and stiff mast.  The pics above show a draft that is behind 50% I think.  I have a C&C too by the way.  Will see if I can get some photos this weekend.

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Two things came to mind. One was the Flying Dutchman. That has always been an interesting overlap problem. I used to helm one. There are some great pictures of funny looking mainsals on them.

And although the opposite of overlapping, the Star mainsail came to mind. They have a strange cut and also that noodle rig and being overpowered leads to all sorts of strange things. Perfect recent photo:

slide9.jpg

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33 minutes ago, Lost in Translation said:

Yes, they are good photos.  Thank you @climenuts.   @JPD, so you have chosen not to run a 150 or 155 and instead use a smaller overlapping headsail in light air?  Or move to the 140 as a number 2 in light / medium?

It's interesting the compromise the main lives with on a keelboat with a fairly large and stiff mast.  The pics above show a draft that is behind 50% I think.  I have a C&C too by the way.  Will see if I can get some photos this weekend.

The 135% Genoa is my largest sail because I race mainly double-handed and the babystay would chew the shit out of a 155% Genoa without someone to help it around. I'm considering going up to the 155% if we keep racing because the 135% lacks power in the light and point at the top of its range.

I'm just starting to get a good handle on flattening the main out and optimizing draft position is my next focus. I think the aft draft and flat luff entry works well on the boat when it builds to the top-end of the 135% Genoa. Seas are usually flat so I point high aided by the flat entry. If it's choppy I have to sail the boat in a completely different twisty low-mode or I hobby horse and don't go anywhere.

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22 hours ago, Zonker said:

Maybe it's just the camera but bottom photo is a pretty big bubble in the main?

It's not a bubble but it's not a uniform shape. The full battens were setup for a lot of draft and the top half of the main's luff is a little stretched out because of a goofy jackline setup the sail originally had.

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17 minutes ago, Zonker said:

How old is the sail? To my uneducated eye it looks like the draft is pretty far aft.

2 years, ~600 Hours. The aft draft is likely user error. I have a tough time getting the appropriate halyard tension with my crappy clutches, 10-speed winches, and stretchy wire halyards.

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On 10/27/2021 at 9:23 AM, Parma said:

I'm curious as to why that works for your boat. Could you explain (readers digest version) what you think is going on with the sails, rig, sheeting angles, point & overall VMG to make that setup work for you? 

That era of boat have pretty broad sheeting angle for the headsails.

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I've got RollyTasker, Performance Tape Drive, both headsail and main,  the right conditions and trimmed well 30-33deg, 40 is easiest, when the bubble occurs I know the mainsail is working properly. 

Quote

 

 

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1 hour ago, Lost in Translation said:

lots of backwinding on a main on my C&C 36 on a windy day where the main is eased to trim to angle of heel.  You can also see how little this mast bends with backstay tension.

1818760390_ScreenShot2021-10-29at10_11_32AM.png

Does this model have a baby stay?

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25 minutes ago, Lost in Translation said:

good question.  It does but I have never used it and am missing the car for the deck.  I wonder how much that would help get some shape.  I have heard they really aren't a pleasure when tacking the boat.

It will help a bit and isn't very far forward on c&c's so tacking is really not more difficult than usual.  That combined with a very well purchased vang will give you a surprising amount of bend compared to what you are seeing in your picture.

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And mark your main halyard at full hoist - you need lots more luff tension in that pic, and your c/ham is maxed out. A babystay WILL get you a lot of bend. Our procedure on a Ranger 32 ( single sprdr, big tube mast) was to max out the b/stay (it pulled forwards on a track) before winding the backstay back on. This would blade out the main quite nicely. We did add a wire belowdecks connecting the track to the hull, to keep from lifting the deck off the bulkhead.

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On 10/28/2021 at 10:38 AM, climenuts said:

I have a tough time getting the appropriate halyard tension with my crappy clutches, 10-speed winches, and stretchy wire halyards.

While wire jib and main halyards have many disadvantages "stretchiness" is not one of them.  Assuming roughly the same SWL, 7x19 pre-stretched  marine halyard wire has less stretch than even the lowest stretch (PBO $$$) line.  Of course wire has no creep or permanent elongation problems and doesn't suffer from UV damage and abrasion problems.  It's gone out of style because of weight aloft (mainly) and handling difficulties.

BTW I'd like to learn more about your 10-speed winches; that's impressive.

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4 hours ago, Lost in Translation said:

lots of backwinding on a main on my C&C 36 on a windy day where the main is eased to trim to angle of heel.  You can also see how little this mast bends with backstay tension.

1818760390_ScreenShot2021-10-29at10_11_32AM.png

Surprisingly large gap between the luff and the sail track.  What kind of shackles are those?

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1 hour ago, Lost in Translation said:

It has a Harken battcar system and webbing loops to connect to the cars. 

I've dealt with Battcars on bigger boats and they're fantastic ($$$) friction free systems especially with full battens.  Something's wrong there, maybe the loops are too long?  I assume you're using the System AA setup.

Edit:  I looked it up in the Harken manual and the webbing span from the luff of the main to the clevis pin center should be about 1".  Your setup is weird with no luff grommets, instead the webbing is sewn into the sail, but it does look like it meets the 1" spec.  So mea culpa.

harken.gif.c8c8c3ffe51c183174ad935dc657da83.gif

yours.jpg.e27bcda8a1c3d423db44ca50cb9ce8cd.jpg

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3 hours ago, axolotl said:

Surprisingly large gap between the luff and the sail track.  What kind of shackles are those?

The C&C Half Ton had a similar or the same set up and gap - so it may be a C&C thing of that era.

 I think it was one of those 70's things where there was some claimed aerodynamic advantage - although I can't recall what the claimed advantage was.

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1 hour ago, 12 metre said:

The C&C Half Ton had a similar or the same set up and gap - so it may be a C&C thing of that era.

 I think it was one of those 70's things where there was some claimed aerodynamic advantage - although I can't recall what the claimed advantage was.

Can't be.  Any leaks from the high pressure side of the main to the low pressure side at the mast (and boom) is slower.  Thus luff rope mainsails are marginally faster, although a hassle because when you drop the main it goes everywhere instead of semi-stacking on the boom if you have track slides.

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3 hours ago, SV Resolute said:

Here's 2 pictures with some speed bubble and baby stay on and last one without babystay in lighter winds.  Please excuse the 40 year old genoa.

Screenshot_20211029-124549_Gallery.jpg

20200803_124610.jpg

20200911_093913.jpg

That Jib doesn't look bad at all...

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1 hour ago, axolotl said:

Can't be.  Any leaks from the high pressure side of the main to the low pressure side at the mast (and boom) is slower.  Thus luff rope mainsails are marginally faster, although a hassle because when you drop the main it goes everywhere instead of semi-stacking on the boom if you have track slides.

IIRC, the notion was to emulate a slotted wing.

1.gif

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17 hours ago, axolotl said:

I've dealt with Battcars on bigger boats and they're fantastic ($$$) friction free systems especially with full battens.  Something's wrong there, maybe the loops are too long?  I assume you're using the System AA setup.

Edit:  I looked it up in the Harken manual and the webbing span from the luff of the main to the clevis pin center should be about 1".  Your setup is weird with no luff grommets, instead the webbing is sewn into the sail, but it does look like it meets the 1" spec.  So mea culpa.

harken.gif.c8c8c3ffe51c183174ad935dc657da83.gif

yours.jpg.e27bcda8a1c3d423db44ca50cb9ce8cd.jpg

It is the Harken Battcar batten receptacle that is the problem with this system. Non-adjustable post on receptacle is stupidly long. Intermediate sliders are webbed on to match that length. I prefer installing the simpler Tides system. Harken's Captive ball bearings are not very captive from what I have seen. HTH

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On 10/27/2021 at 7:29 PM, blunted said:

Some people may go insane over what I have to offer here.

Backwinding isn't always a bad thing.

It's ugly and has a bit of drag but its not the part of the sail plan doing anything very useful.

The luff of the jib is doing the most work in the whole sail plan and everything after that is just trying to hang onto flow. If you have a big overlap you just have an oversized slot which is there to accelerate flow on the lee of the main behind the end of the slot and help keep flow stuck to that part of the total sail plan. The bubble in the main is just the sail trying to get out of it's own way in the slot.

Downwind, is your main doing anything useful? Does it actually have flow over it or are you doing W/L courses sailing deep and relying on your pretty sail up front with the main there as a billboard? If so, I'd just go with a flatter main. If you are doing a bunch of reaching or VMG sailing and your main actually has flow downhill, I'd be inclined to get something with some more depth and then use the tools you do have to flatten it out going upwind.

Note, I grew up racing 8 Meters with massively overlapping headsails and constantly backwinded mains with fairly narrow sheeting angles. I moved on to sailing boats with wings where we control the slot to the millimeter. What did I learn? SLOT IS EVERYTHING and the individual sails don't matter, only how the sail plan works as a whole matters, just consider it as one aerofoil with a slot in it like a big plane with flaps down at takeoff. Goal is to bend air as much as you need or dare matched to heeling moment for the lowest drag you can get. To bend air a long way you need it stuck to the lee side of the foil (Main and Jib) from front to back without it detaching. The slot injects additional energy into the boundary layer which keeps the flow stuck to the main to the end of the leech without stagnation. That's the goal.

 

I agree with a lot of this, especially with the two sails forming one wing. However, I think there is one important difference between the solid wings and a main and jib combination which is that the gap size differs by orders of magnitude. Hence the flow regime inside the gap are quite different.

Anyway, if you consider main and jib as one wing, one could argue that increasing the sheeting angle of your jib might help (think inverse jib inhauler). Many people will argue that you will lose height doing this. However, if the leech of your main is the trailing edge of your compound wing then the angle of attack would not change.

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