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Are genoa's a thing of the past?


PinkSpinnaker

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I have not seen any (maybe I am not looking hard enough) newly designed sailboats with a genoa, but I am sure this is due to the boats design. Does that make genoa's a thing of the past?

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IRC didn't like them so that contributed to their downfall. Over 5 knots and with a correctly sized main blades are more efficient uphill. They suck reaching. Like awfully. No power at the top of the sail. Hence the development of the code zero which is very necessary if you're reaching on a modern boat.

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Pain in the ass they may be, but there is nothing like a well cut 155% for going upwind in 5-10. As long as there are "older" boats out there racing PHRF and larcenous sailmakers looking to make a buck, genoas will be around for awhile.

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Not a rule cheat, mostly that's the shape that sail cloth of old could handle - an equilateral triangle. Spars were short, due to materials (decaying vegetable matter), soft bronze metals, deadeyes to tighten the shrouds, hulls with no form stability coupled with shallow keels all meant the overlapping sail was the only easy way to get large sail areas.

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Not a rule cheat, mostly that's the shape that sail cloth of old could handle - an equilateral triangle. Spars were short, due to materials (decaying vegetable matter), soft bronze metals, deadeyes to tighten the shrouds, hulls with no form stability coupled with shallow keels all meant the overlapping sail was the only easy way to get large sail areas.

 

 

Oh yes, Raz'r is right, a rule cheat. Used first time by Sven Salén in a regatta in the Italian town named Genoa, in 1927.

 

Definitions vary somewhat, often a jib is said to not go behind the mast, if it does it is a genoa. But then, 110% jibs are not unknown.

 

Genoa did have their peak during RORC and IOR rules, usually rather short masthead (under rigged) - the hulls of that ear couldn't be said to be slim ... Rule makes wanted safe boats, usually rather heavy and under rigged. All this resulted in heavy use of genoas. A Norlin 37 has a genoa 1 of ~60 sqm, genoa 2 is ~50 sqm ... heavy sails to sheet. Another example is the Ballad which often was sailed with the genoa up to 12 m/s (~24 knots) of wind. Heavy!

 

Since then fractional rig has become popular again. Genoas are still useful, but of course those who have the pockets for a set of code:s and all other new variations will go along that route.

 

However, we have seen this before. After rain comes sunshine ... the racing rules will direct hull and sail design. There was a time when everybody viewed the jib as a thing of the past, maybe used in a bad storm. That changed back, the same may very well be true about genoas. We have now had genoas for about 100 years.

 

/J

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to get back to the original statement/question. the J109 was designed to carry Genoas and it is a rather newish design. so yes, it has happened. there are 36.7s that are designed with genoas.

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Code zero, the CCA genoa of the 2010's

xacry. Genoas on big boats wax and wane with the rating rules.

 

In development classes with open rules (dinghies, beach cats, AC cats?), where only measured total sail area is rated, genoas are dead. It either cat rigs or small jibs.

 

That tells me they're not efficient for their size.

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As sail area restricted classes show, overlap is an inefficient place to put sail cloth. Only worth putting there if it's cheap from a rating point of view. Or a bit of entryism by sailmakers has overthrown the bourgeois class structure of the rating authority, and as a result they want everybody to have to use sails which get shredded every tack.

 

 

2006pitsford16.jpg11.jpg

 

2745166_1_O.jpgyandy121550.jpg

 

yandy138708.jpg

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Not a rule cheat, mostly that's the shape that sail cloth of old could handle - an equilateral triangle. Spars were short, due to materials (decaying vegetable matter), soft bronze metals, deadeyes to tighten the shrouds, hulls with no form stability coupled with shallow keels all meant the overlapping sail was the only easy way to get large sail areas.

 

 

Oh yes, Raz'r is right, a rule cheat. Used first time by Sven Salén in a regatta in the Italian town named Genoa, in 1927.

 

Not a rule cheat as I understand it - more of a surprise. The race was held in 6 metres. In those days, 6m's carried a non-overlap jib for windward work and an overlapping reaching headsail. The boat in question was so far behind the fleet at the bottom mark that the skipper called not to change to the upwind jib because it wasn't worth the effort. But it was a light breeze and the additional sail area powered them past the fleet for a win (as the story goes) and, yes, because the race was held at Genoa, the sail got that name.

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I once heard that sail inventory changed dramatically when Hood got involved. Designed boats to have small mains and multiple headsail inventories. The full argument, which did make sense, but I cannot repeat it so it does, was along the lines of comparing traditional sail plans with more modern ones, where a properly reefed large main with one or two headsail was all that would really be needed.

There may have been something about furlers in it as well, I can't remember

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The CCA Rule saw 200% lp genoas

The IOR Rule reduced that to 170% and brought about blade mains

The IMS (MHS) Rule brought back large mains

The IRC (CHS) Rule knock genoas down to 110% Jibs

The ORR Rule will probably usher in an increase in genoa size.

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mostly rule driven.., but mast and rigging technology improvements have made it easier to have tall light masts with thin sections that stay up.., enabling bigger mainsails to be more common.

 

to some extent sail area was distributed over more sails down low because it was harder to get the area up high

 

also keel technology has changed a lot..,hull shapes have changed.., so boats have more initial stability - they are stiffer - so they don't heel as much from having sail area up so high

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mostly rule driven.., but mast and rigging technology improvements have made it easier to have tall light masts with thin sections that stay up.., enabling bigger mainsails to be more common.

 

to some extent sail area was distributed over more sails down low because it was harder to get the area up high

 

Just going to throw this out there... :) For big mainsails and lots of area high up, hard to beat this:

 

xreliance-shamrock-on-page.jpg.pagespeed

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Genoa did have their peak during RORC and IOR rules, usually rather short masthead (under rigged) - the hulls of that ear couldn't be said to be slim ... Rule makes wanted safe boats, usually rather heavy and under rigged. All this resulted in heavy use of genoas. A Norlin 37 has a genoa 1 of ~60 sqm, genoa 2 is ~50 sqm ... heavy sails to sheet. Another example is the Ballad which often was sailed with the genoa up to 12 m/s (~24 knots) of wind. Heavy!

 

/J

 

Yeah, the Ballad's working headsail is 150% masthead (G1), with an option for 165% and some racers carry the full kit up to 30kts. For shorthanded cruising, we plan to use a 135% on a furler & keep a 145% flying Zero for the light. The mainsail foot is a ludicrous 9'6"; when time comes to replace the main, we might add 18" to the boom & as much roach as we can get away with. Counterintuitively, shrinking the genoa and adding mainsail actually moves the net center of effort slightly forward and down. :blink: So much of the G1 is behind the mast. And yet, the Ballad in standard trim is considered an upwind machine, so the added drag doesn't seem to hurt its angles. Speed, maybe.

 

 

 

With 47% ballast ratio & that as lead (carried low), would the smart thing be a taller mast & blade jib? Boat's stiff enuf to sail a cheater kite plastered to the forestay, with headsail inside -- like a 5o5, but no hiking required!

 

b6448f9e15.jpg

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There is at least an element of truth in almost every previous post

 

With regards to IOR. Rated SA (RSAT) was determined mainly by I,J,P, & E. RSAF assumed a base LP of something like 150% or 155%. No reduction for LP less than that, but an LP over that would increase RSAF.

 

In truth, IOR favoured big low AR mains - not small skinny ones. At least from the perspective of largest SA for the smallest RSAT. The initial preference of small skinny mains in IOR may have been because that worked best on the earlier heavier IOR hulls - but the kiwi designers were the first to take advantage of using big low AR mains, which also worked well with their more dinghy like hulls.

 

As an example, in the early 80's, the One Tonner I was sailing on revised the sail plan by increasing E of the main by 2-2.5 ft. Actual SA increased some 55 sq ft but RSAT only went up by 11.

 

How did that work? For starters RSAM was calculated at .35 x P x E (in other words 70% of geometric area). Then there was a reduced High Aspect Ratio multiplier, Then there was a reduced multiplier for RSAF/RSAM (essentially an increasing credit for boats that had a higher proportion of total SA residing within the main. There may have been more rating advantages of big mains, but these were the big three.

 

Taking this to the extreme resulted in L'Effrai (sp?) the French mini-ton cat sloop. Shortly after, IOR either outright banned this or implemented a minimum RSAF, not sure which.

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Have a 155% Genoa on mine, hate the thing. Catches on everything when I tack, short tacking should not be this much work on a 25 footer.

 

Can't even get away with a 130% because as is typical of the era the rig is too small.

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Overlapping furling headsails still have a place on short rig cruising boats in terms of versatility. Reaching (without cost and room required to carry more efficient Codes), poling out for VMG running instead of symetric kites and upwind in stiffer conditions simply rolled up and revert to using only an inner blade, either hanked or on a furler.

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There is at least an element of truth in almost every previous post

 

With regards to IOR. Rated SA (RSAT) was determined mainly by I,J,P, & E. RSAF assumed a base LP of something like 150% or 155%. No reduction for LP less than that, but an LP over that would increase RSAF.

 

In truth, IOR favoured big low AR mains - not small skinny ones. At least from the perspective of largest SA for the smallest RSAT. The initial preference of small skinny mains in IOR may have been because that worked best on the earlier heavier IOR hulls - but the kiwi designers were the first to take advantage of using big low AR mains, which also worked well with their more dinghy like hulls.

 

As an example, in the early 80's, the One Tonner I was sailing on revised the sail plan by increasing E of the main by 2-2.5 ft. Actual SA increased some 55 sq ft but RSAT only went up by 11.

 

How did that work? For starters RSAM was calculated at .35 x P x E (in other words 70% of geometric area). Then there was a reduced High Aspect Ratio multiplier, Then there was a reduced multiplier for RSAF/RSAM (essentially an increasing credit for boats that had a higher proportion of total SA residing within the main. There may have been more rating advantages of big mains, but these were the big three.

 

Taking this to the extreme resulted in L'Effrai (sp?) the French mini-ton cat sloop. Shortly after, IOR either outright banned this or implemented a minimum RSAF, not sure which.

 

Spinnaker area is a function of J and jib hoist-----which leads to small skinny mains....

 

 

That was likely the original thinking, but by the late seventies most new IOR boats were frac rigs with large lower aspect ratio mains.

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I hope so, short tacking with heavy #1 on old IOR boats was fucking hard work.

 

On my Quarter Pounder I had a guy at the mast to bring the 150 across the baby stay.

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I hope so, short tacking with heavy #1 on old IOR boats was fucking hard work.

 

On my Quarter Pounder I had a guy at the mast to bring the 150 across the baby stay.

 

 

Glad to see the back of those things as well. :P

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Ultra light floater

Light No. 1

Medium No.1

Heavy No.1

No.2

No.3 blade

No.4

 

What's not to like having all those on your fore-deck, side-deck, exploded down below when the seabreeze or front comes down the beat :-)

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And a track for each of them on the deck

Peeling sheets all f*ked up and too little winches/jammers to put sheets on which by that time are half way under water anyway :-)

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Ultra light floater

Light No. 1

Medium No.1

Heavy No.1

No.2

No.3 blade

No.4

 

What's not to like having all those on your fore-deck, side-deck, exploded down below when the seabreeze or front comes down the beat :-)

Only the larger boats carried that many. Usually just a light and heavy #1, frac rigs eliminated the #2.
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Ultra light floater

Light No. 1

Medium No.1

Heavy No.1

No.2

No.3 blade

No.4

 

What's not to like having all those on your fore-deck, side-deck, exploded down below when the seabreeze or front comes down the beat :-)

Only the larger boats carried that many. Usually just a light and heavy #1, frac rigs eliminated the #2.

 

 

I don't know, on my 24ft Eygthene we had a 1, 2, 3, 4, Working Jib, Storm Jib.

That's like 6 headsails.

 

Fractional all the way now.

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I have 153% genoas that I think are critical to driving our boat, and I generally would not call the boat under-rigged. There is a big geometry component to why certain boats like or need certain sails - it's not just about the aerodynamics of overlap. If I could figure out how to build a properly fast light 100% jib for this boat I would love to try it. I'd trade that for spinnaker area in a heartbeat.

 

With the light #1 in the picture below, when it blows zero-1 knot we don't make much headway, but in 2-5 we can just about hang upwind with boats like the 1D35 and Farr 30, so you know the rig works when the conditions come to it...

 

post-257-0-76302700-1460400633_thumb.jpeg

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The CCA Rule saw 200% lp genoas

The IOR Rule reduced that to 170% and brought about blade mains

The IMS (MHS) Rule brought back large mains

The IRC (CHS) Rule knock genoas down to 110% Jibs

The ORR Rule will probably usher in an increase in genoa size.

And pretty soon we can break out the bell bottoms
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Genoa did have their peak during RORC and IOR rules, usually rather short masthead (under rigged) - the hulls of that ear couldn't be said to be slim ... Rule makes wanted safe boats, usually rather heavy and under rigged. All this resulted in heavy use of genoas. A Norlin 37 has a genoa 1 of ~60 sqm, genoa 2 is ~50 sqm ... heavy sails to sheet. Another example is the Ballad which often was sailed with the genoa up to 12 m/s (~24 knots) of wind. Heavy!

 

/J

Yeah, the Ballad's working headsail is 150% masthead (G1), with an option for 165% and some racers carry the full kit up to 30kts. For shorthanded cruising, we plan to use a 135% on a furler & keep a 145% flying Zero for the light. The mainsail foot is a ludicrous 9'6"; when time comes to replace the main, we might add 18" to the boom & as much roach as we can get away with. Counterintuitively, shrinking the genoa and adding mainsail actually moves the net center of effort slightly forward and down. :blink: So much of the G1 is behind the mast. And yet, the Ballad in standard trim is considered an upwind machine, so the added drag doesn't seem to hurt its angles. Speed, maybe.

 

 

 

With 47% ballast ratio & that as lead (carried low), would the smart thing be a taller mast & blade jib? Boat's stiff enuf to sail a cheater kite plastered to the forestay, with headsail inside -- like a 5o5, but no hiking required!

 

b6448f9e15.jpg

 

Not sure that's fast

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I submit a different interpretation. The gospel, according to IOR during the 70s, was headsails were supposedly more efficient upwind and down so rig dimensions tended to emphasize J and I (masthead rigs). Sail area is sail area so, to maximize power to windward without over canvassing, the higher aspect, skinny, main provided more upwind drive for given amount of reduced area and relied upon the big spinny pulling you downhill. Something like a jib top was usually carried for long reaches to compensate for the poor off the wind performance of genoas and skinny mains. I had an early IOR influenced Yamaha 33 that we raced in PHRF against CCA influenced Ranger 33s. We crushed them going upwind but lost it all back as soon as we turned the corner. The Ranger had a slightly shorter rig with a much longer boom. I guess a better spinny would have helped us downwind but we were on a budget.

 

I think it was the Southern Hemisphere lads that discovered more sail area with less penalty was the better way to go and the move to bendy, fractional rigs was on.

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Not sure that's fast

 

Yet that's a pretty good bow/quarter wave for a 1970s leadmine in -- what? -- ten knots true? :) WIth big genoas (which we all agree are problematic) and tiny mains (171 sqft!), no asyms or Codes on sprits (that photo is OD racing at Kieler Woch), and so much of the boat's allowable sail area in the spinnaker, top sailors of these boats have found hoisting the kite as early as it will stand (& using the genoa as a spinnaker saysail) yields the best speed in light winds. The drag is always there, goes the logic; so let's maximize lift using a projected sail with big shoulders. You've got the RM for it, right? Might not be fast on an Etchells, but it seems to work for these boats on short courses.

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Ultra light floater

Light No. 1

Medium No.1

Heavy No.1

No.2

No.3 blade

No.4

 

What's not to like having all those on your fore-deck, side-deck, exploded down below when the seabreeze or front comes down the beat :-)

and the reacher with the staysail, tallboy and bigboy plus 1/2 oz 3/4 oz 1 1/2 oz and the 2.2 oz kites plenty of sails for move around and sleep on.

 

Those where the days when the IOR owners where the sailmakers best friend. ^_^

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Heartily disagree that sail area is sail area, which is a weakness of PHRF. On the other hand, it makes the calculations easy and is only used for base rating adjustments - not the ratings themselves, so works fairly well in that context.

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Ultra light floater

Light No. 1

Medium No.1

Heavy No.1

No.2

No.3 blade

No.4

 

What's not to like having all those on your fore-deck, side-deck, exploded down below when the seabreeze or front comes down the beat :-)

Only the larger boats carried that many. Usually just a light and heavy #1, frac rigs eliminated the #2.

I've gone to a Lt.1, 2, 3, 4, JT.

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Heartily disagree that sail area is sail area, which is a weakness of PHRF. On the other hand, it makes the calculations easy and is only used for base rating adjustments - not the ratings themselves, so works fairly well in that context.

Agree.

IRC is slightly more clever as it rates the sails aspect ratio also. Hence rule 21.7.3

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Sail area ain't sail area. If you agree that using the rudder a lot, or having to put a ton of weight on the rail both slow the boat down, then the allocation of sail area fore-to-aft is really important. A balanced sail plan is faster than a sail plan that makes the helm fight with the rudder.

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I can confidently say that I won't own another boat that has anything bigger than a 110% as a standard working size. hell, I might go as far as saying Self-Tackers are us....

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I always understood their demise had to do with dollars. You have one mainsail, multiple headsails and spinnakers. Small main = tons of yards of headsails and spinnakers. Big main = lots less cloth in headsails and spinnakers.

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Unless class rules limit the inventory, you're still looking at a light jib and heavy jib. Saving a #2 and 3 (the jibs are in essence a 3). Either case, race rules may require a #4 and SJ. Sails are smaller, which helps. W-L bouy races saves a JT and staysail. Still probably need 3 kites.

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I was trying to make a point about heeling moment and I obviously screwed that one royally. Sail area is sail area when you're concerned about how much heeling force is generated going to weather. To handle the bigger headsails without taking knockdowns in 12 kts of true wind, the main was made smaller. It was also skinnier which meant higher aspect ratio allowing more forward drive from the reduced area. I'm not saying it was a great idea, just the prevailing theory of the time.

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https://www.facebook.com/aquaeolo/videos/923071247808165/

 

Some good Genoa stuff here, Cowes 1968...fuck all breeze and honking current!

 

 

Hey! How about that tricked-out roller reefing mainsheet claw! <_<

 

Did you know you can still buy a new Procter mast in 2016?

 

Never mind that - X117 (XRay) seen in the final shot is still racing regularly.

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  • 2 weeks later...

I can confidently say that I won't own another boat that has anything bigger than a 110% as a standard working size. hell, I might go as far as saying Self-Tackers are us....

useless? No, those blade days are the best, and that's a self tacker, sort of. Has anyone mentioned that a 120 or bigger heaves to better than a 90 or 100? That's my experience. (Limited as it is)

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  • 3 months later...

I got a big laugh when I read thru this subject thread. Its interesting to see the big number of references to how the rules influenced the sailing rig designs/sail deployments.

I have this gentleman (CT249) over on this other forum that continually insist that there is no connection. He insist that the rig configurations gravitate toward the best overall design (the fractional rig sloop in his opinion) rather than any other possible configurations.

Here are a couple of links to his postings:
http://www.boatdesign.net/forums/sailboats/aftmast-rigs-623-59.html#post762843

 

http://www.boatdesign.net/forums/sailboats/aftmast-rigs-623-58.html#post762667

 

*******************************************

...and another,

CT249 wrote

If you know that, then you must be right and every successful racing boat designer in the world must be wrong. That means that reckon you know more than Farr, VPLP, Irens, S&S, Peterson, Holland, AMAC, Reichel and Pugh, Botin, Carkeek, Bethwaite, Morrison, Bieker and dozens more, including aerodynamic experts from MIT, Boeing and other places.

 

Brian responded:

I repeat again, it is not always a favorable situation for designers to 'go-off-the-beaten-path', either on a financial basis, or a reputation basis. If the current RULES don't allow unusual variations in the rigs (etc), then the boat's owner may suffer being disallowed to race, and possible even suffering a lost of resale value in his vessel. Subsequently the designer may in turn suffer in follow-on commissions to design, etc.

So its not always a question as to whether a new idea has some viability, but rather will it fit in with the established 'norm' allowed under the rules.

I posted a related question about some ideas that Herreshoff tried introducing to the yachting scene, and was rejected by rating rules:
sail aerodynamics

***************************************************

 

NOTE: He is often responding to my interest and postings of unusual sailing rigs, particularly one I have been promoting that carries two headsails plus a mizzen sail,....no mainsail.....a cruising rig design that carries a 105% genoa.

 

Revisiting a Mast-Aft Sailing Rig
by Brian Eiland

Twenty five years ago, I was a younger fellow aspiring to become a sailing yacht designer. I was particularly interested in ocean going, cruising boats. I would devour every reference I could find on what made sailboats work. With keen interest I followed new developments on the racing circuits, believing that this was the incubator of fresh new ideas to speed our progress across the seas. Surely this breeding ground would bring significant evolution to the sport of sailing and the art of designing.

"Au contraire", I became disillusioned so soon. Bruce King's fantastic twin, asymmetrical, bilgeboard development, disappeared in little over a year. Prof. Jerry Milgrams cat-ketches were afforded a similar welcome. Truely different sail rig innovations were totally discouraged, and numerous other design innovations were "rated" out of existence by handicap racing rules. Ocean going boats were not being designed to "mother-ocean's rules", but rather to some arbitrary, man-created, racer/cruiser rule.

http://www.runningtideyachts.com/sail/

(more like 40 years ago now)

 

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Thread drift: I applied for a PHRF rating in a new district - we have always raced our boat OD, like for the last 45 years - and the handicapper gave me a long lecture about my 167% headsail (class rules) and how we were going to get a 6 second hit from our base rating. The boat was designed to carry a 170%. Shouldn't the "base rating" be based on the design of the boat? Why is a base rating for a 155% (our #2). I don't really care what my rating ends up being, these are the sails I have and I intend to stay class legal. However, it seems a little myopic. I'd think that any boat that CHOSE to carry a 155% should get a credit from the base instead of the other way around.

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I have not seen any (maybe I am not looking hard enough) newly designed sailboats with a genoa, but I am sure this is due to the boats design. Does that make genoa's a thing of the past?

Yes, the sport has become a sport for pussies.

No more genoa's to have to muscle in in 15-20 and no more spin poles to have to muscle on jibes in 20-30.

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Pain in the ass they may be, but there is nothing like a well cut 155% for going upwind in 5-10. As long as there are "older" boats out there racing PHRF and larcenous sailmakers looking to make a buck, genoas will be around for awhile.

 

Except maybe the big-ass mainsail the boat should have had in the first place, but didn't get because of rating rules

 

FB- Doug

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...from another forum...
I think Tom Speer & I are both in agreement as to the superiority of the genoa sail from an aerodynamic viewpoint. And we are in agreement that much of its superiority is gained as a result of its interaction with the mainsail. (We had previous discussions of this interactivity under the subject headings, “The Slot Effect” and “How Sails Work”. Where we probably come to differ a bit is the extent of this superiority of the headsail. I give it greater creditability than he does……and particularly as I have it designed.

We know that the restriction presented by the ‘slot’ tends to divert more air around the two sides of the slot, i.e. the windward side of the main and the leeward side of the genoa. This higher flow rate on the lee side of the headsail increases its effectiveness. Now if we also overlap the mainsail with the trailing edge of the headsail, we further increase the effectiveness of the headsail, as it is able to carry this increased flow rate much further aft along its span than if it was to have to dump its flow at free stream velocities up at the leading edge of the mainsail. This overlap is important.

Now imagine looking down on the sailing rigs from directly overhead and evaluating the cross-sections at various vertical levels ( I probably should draw a diagram of this view and post it on my website). You would discover that my two parallel headstays present uniformity in both the slot between the two sails, as well as the overlap of these two sails. And this uniformity is consistent from the foot of the sails up to the hounds.

Significantly this is no-where near the case with the traditional Bermudan rig, either fractional or masthead configured. In both of these cases the throat of the slot is decreasing in size as we move vertically up the mast, while the wind velocity is increasing with this height……sort of a reverse of what we might desire. And the overlap of the necessarily hollow-leached headsail is at best really only effective at the bottom 1/3 of the sailplan. Seems there are many more questions of the compatible interactivity of the main and the headsail of the Bermudan configuration than with my twin headsail arrangement. In this comparison I think my rig configuration will prove significantly superior.

Note also that this nice uniform genoa overlap is attained while utilizing only what amounts to a 110-120% genoa rather than a radical 150-180% sail (Bermuda rig designations). And the foot areas are fully compatible, unlike the raised boom region of the Bermuda rig. Above the hounds the natural twist in apparent wind should help to make this upper portion of my genoa be a more productive sail area, certainly more productive than the thin strip of Bermudan mainsail hidden behind a mast structure on a fractional rig vessel. Just possibly the slot formed between my bare mast and the genoa sail in this upper region may create an upwash that could assist this productive task.

 

I also find it interesting that the latest ‘state-of-the-art’ Volvo 60’s appear to be evolving from their fractional rig plans to a masthead arrangement with their new flat cambered Code Zero sails (large genoas?) for close reaching work. I think this speaks to the superiority of the masthead verses fractional rig. Just when we thought evolution was favoring a smaller jib/larger main, things re-adjust. Evolution doesn’t always follow mother nature’s preferred path, it can get skewed off- -course a bit following rules put in place by handicappers.

While on this flow subject, I wish to bring up one other matter. Almost no one including the textbooks addresses the triangular nature of the slot (throat of the slot) in the traditional Bermudan rig, and how this might redirect (divert) some portions of the airflow up or down vertically (3 dimensions)? Everything is treated in a 2 dimensional manner, in a plane parallel to the water’s surface. Wouldn’t this more restrictive slot at the upper regions combined with an increased flow velocity, tend to deflect some airflow in a vertical manner? I’ve certainly seen it with my telltails…..and if my Bermudan mainsail is diverting wind upwards it must be pushing back downward on my mainsail (for every action there is an opposite and equal reaction). Or how about that ‘lift’ I seem to experience with some headsails. Where is the theoretical data to suggest and/or collaborate these observations? Things in nature don’t always follow our assumed calculated rules.

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Overlap Dynamics

Overlap Dynamics
Quote:
Originally Posted by Paul Scott
Anywere I can find more info about overlap dynamics? (that is vs no overlap?)
If DP is right about the air accelerating (after stagnating at the entrance to the slot) "as it approaches the leach of the genoa, reducing pressure and re-establishing the suction that produces the mainsail's drive", does this have design repurcussions, like where the leach of the genoa ideally ends relative to the maximum chord of the main, and does it change where you would want the point of maximum camber on the main for that particular genoa?
Overlap dynamics: Have a look at back thru Postings # 63,64,65,66 of this subject thread.
http://boatdesign.net/forums/showpos...4&postcount=63
http://boatdesign.net/forums/showpos...4&postcount=64
http://boatdesign.net/forums/showpos...4&postcount=65
http://boatdesign.net/forums/showpos...4&postcount=66

And then an excerpt from here, "We know that the restriction presented by the ‘slot’ tends to divert more air around the two sides of the slot, i.e. the windward side of the main and the leeward side of the genoa. This higher flow rate on the lee side of the headsail increases its effectiveness. Now if we also overlap the mainsail with the trailing edge of the headsail, we further increase the effectiveness of the headsail, as it is able to carry this increased flow rate much further aft along its span than if it was to have to dump its flow at free stream velocities up at the leading edge of the mainsail. This overlap is important."
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The main reason a Code 0 works is because it is usually rated as a spin and so has a lot of unrated area as a headsail. If they were measured as a jib, I think they would disappear pretty quickly from the face of the earth in most classes.

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Genoas/Code 0 are one way to add area to a boat that needs more sail for a given rig.

 

A cat wing with appropriate slots is probably the most efficient in terms of raw area,

 

A big wing with small jib next and then you evolve towards masthead sloops and divided rigs where the complexity of rigging and multiple sails gives diminishing returns upwind.

 

Most effective for a given rig investment will still favor raw area and that's masthead genoa/code 0.

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Makes sailing non-spin beer can races in light wind sucky when everyone else has 150 genoas and you have an itty bitty headsail and swept back spreaders.

Tight reach inlight air and with the 1 up the sc27 was motoring along and longer boats with the smaller headsails did not begin to pull away until the wind picked up.

 

I like having the option to run a bit overpowered with a headsail when the sea is bumpy. I have toyed with getting a short hoist heavy 140 cause you can reef the main and flatten the heqdsail and power upwind maybe not so efficiently but shorthanded downwind in a breeze you can pole it out and go ddw with much more stability than the chute. Kind of old lazy man sail.

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The 30 Square Metre class from way back when (still racing, BTW) took genoa jibs to an interesting extreme.

 

2000px-Bijou_30_qm_Sch%C3%A4renkreuzer.s

Rating anomaly. Any area beyond 80% J (I think) was free. My experience was it didn't necessarily make it faster up wind, but cracked a little....

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Dont tell the J29 guys in 16-18 with the H1 up and 7 guys hiking their asses off. They might not understand

Exactly!

Anytime you would like a try at getting it inside the lifelines tack after tack in those conditions, look me up for shot at it! :o

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  • 2 weeks later...

Genoas/Code 0 are one way to add area to a boat that needs more sail for a given rig.

 

A cat wing with appropriate slots is probably the most efficient in terms of raw area,

 

A big wing with small jib next and then you evolve towards masthead sloops and divided rigs where the complexity of rigging and multiple sails gives diminishing returns upwind.

 

Most effective for a given rig investment will still favor raw area and that's masthead genoa/code 0.

 

I posted this over here:

http://www.boatdesign.net/forums/sailboats/code-zero-sails-aerodynamic-questions-53291.html

 

Code Zero Sails, aerodynamic questions

I was looking to restudy some of the aerodynamics of the 'code zero' sails that we see an increasing usage of since their original development on the Whitbread boats. We now see more use of these type of sails on very fast multihulls (particularly foiling ones) that bring their apparent winds so far around on the nose.

 

To my mind's eye, I often tend to look at them as a big genoas, as I found this article that expresses the same. I've made a copy of that article here, as often these things can disappear after some period of time in this modern world of SO MUCH information. I hope it does not, as there are some good illustrations that accompany the article.

http://northsails.com/tabid/27323/Default.aspx

(sorry, that freaking link is no longer viable,...as happens often these days )

 

 

Code Zero" (A0) Asymmetric Spinnakers

Part genoa, part asymmetric reacher... is the A0 (aka "Code Zero") right for you?

Quote:

In the opening leg of the 1997-98 Whitbread Around the World Race EF Language unveiled a “secret weapon.” It was a new close-reaching asymmetric developed by North sail designers dubbed the “Code Zero,” and it vaulted EFL to an early lead the team would never relinquish. A decade later, North “Code Zero” (A0) asymmetrics are versatile members of mainstream inventories... not only used by boats that spend a lot of time close reaching in light air, but also in windier conditions and wider angles.

 

What they do

Code Zero asymmetrics fit effectively into the crossover gap between a genoa and the ubiquitous 3A asymmetric reacher. They provide additional power at approx. 40-degrees AWA in true wind speeds under 10 knots; conditions that are typically slow with conventional sails. Code Zeros have also proved effective for reaching in 15-25 knot winds at 80 to 90 degree apparent wind angles. Most boats sailing offshore can put a Code Zero to good use.

 

Code Zero Design

Code Zeros are closer to a oversized hybrid genoa than they are to a typical asymmetric spinnaker. For racers, a Code Zero wants to measure as close to a genoa as possible while still qualifying as a legal spinnaker. They are designed with a flatter shape than other asymmetrics, yet still fly without the leech flapping. The draft sections are evenly shaped with a mid-stripe camber of around 20%. A typical light genoa’s mid camber is around 16% and a V-Series 1A asymmtric’s mid camber is around 23%. The Zero has more vertical curvature than a genoa and carries a much more twisted flying shape. The luff needs to set relatively straight and the leech has a small positive fan (roach). Wind tunnel testing indicates this configuration increases forward force with a lower side force and center of effort than a fuller sail with more normal edge profiles.

 

Code Zero design can be affected by limits placed on them by rating rules, handicaps or class rules. Typically, that means:

1)The leech must be less than 95% of the luff in length.

2)Mid girth must be at least 75% of the foot length. (This is in the RRS, as well)

3)Additionally, asymmetrics are limited to a maximum width (girth limited) or to an area through a formula using luff, leech, foot and mid girth

 

A Code Zero luff should be as long as the rig allows. This is determined by measuring the distance from the raised halyard point to wherever the tack will set. Ideally, the tack point is a strong fixture on the boat forward of the headstay. These sails are rarely set on conventional spinnaker poles and extreme caution should be used setting a Code Zero on retractable sprit-style poles. Zeros exert a lot of upward force in order to fly with the luff as straight as possible. If the sail will set on a furler (recommended), clearance between the drum and the headstay must also be accommodated. The leech is designed close to the maximum allowed. The foot is usually close to half the luff length, but also can be governed by handicap, rating or class rules. Girth-limited Code Zeros may need shorter foots. Area limited sails might need longer foots if there is a minimum area requirement that needs to be met.

 

Code Zero sail handling

There are two methods of handling Code Zeros. The preferred is a roller furling luff, which allows the sail to be rolled and stowed in a spinnaker box bag. When raising, simply hook up the corners, hoist and release the furling line as the sail is sheeted in. An alternative method is lots of good stopping yarn or zippered snakes.

 

When setting the sail, make sure the luff cord is tensioned more tightly than you think would ever be needed. Tie it off as short as possible as it is easier to ease than add tension later. The sail should set with minimum cloth tension on the luff.

 

Some rig builders advise the use of a 2:1 halyard in order to reduce compression on the spar. In any case, the halyard needs to be very low stretch and very strong. The sheeting point is usually the spinnaker sheet block, although a tweaker might be required. Leech cord tension is very sensitive and can span a wide range. When tensioned to stop the flapping, expect to see considerable curl in the leech. This is the inevitable result of the amount of leech fan required to meet the minimum mid girth restriction.

 

Takedowns with a furler are fairly simple. Without one, the best method is bear off with lots of hands. Spiking off the tack and using the gap between the boom and mainsail foot to smother the sail also works well.

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http://www.boatdesign.net/forums/sailboats/code-zero-sails-aerodynamic-questions-53291.html#post737374

How Sails Work, the slot effect (Yeah, another long one)

 

From: brian eiland
>We now know irrefutably that the flow between
>these two sails is SLOWED rather than speeded up, and that results in a
higher pressure on lee side of the jib and on the windward side of the main;


As Brian has pointed out, the reason the slot does not work entirely like a
conventional venturi is because the mass of air flowing through the slot is
not constant as you change the gap. As you close the slot less mass flows
through it and more mass flows around the sail with the dividing streamline
(separating the air that goes to leeward from that which passes to windward)
moving to windward.

The finest explanation I've seen of the slot effect was given by A.M.O.
Smith in his 1975 Wright Brothers Lecture ("High Lift Aerodynamics," AIAA
Journal of Aircraft, Vol. 12, No. 6, June, 1975, pp 501-530). This should
be available from any university engineering library.

Smith starts out by considering what limits the amount of lift a section can
provide and shows that there are two basic factors: when the local pressure
reaches Mo^2*Cp = -1 [Mo is the freestream Mach number and Cp is the local
pressure coefficient], and when the boundary layer separates. The first
criterion places an absolute limit on the lift that can be produced
regardless of the type of high lift device.

The second, the load-carrying capacity of the boundary layer, is what sets
the limit in nearly all practical cases. For attached flow, the velocity at
the trailing edge is a little slower than, and the pressure a little higher
than for the freestream conditions. Somewhere ahead of the trailing edge
the local velocity is higher and the pressure is lower. So the last thing
the boundary layer has to do as it gets to the trailing edge is to negotiate
a region of increasing pressure and decelerating flow. If the increase in
pressure is too much the slower flow in the boundary layer literally gets
backed up. This is what causes separation - you have flow moving forward
meeting flow being pushed backwards, both get brought to a stop at some
point, and the only direction they can both go is away from the surface. So
there's a limit to how suddenly the flow can be decelerated.

The harder you can decelerate the flow, the longer you can maintain the
higher velocity on the lee side and the more lift you can produce. It's
just like coming up to a stop sign - you can either coast into it from a
long way out, or you can come zooming in and slam on the brakes at the last
minute. It turns out that the velocity profile for maximum deceleration of
the flow has a concave shape - a steep drop at the beginning when the
boundary layer is fresh, and a pronounced flattening out of the profile with
distance from the start of the drop (kind of like a car whose brakes fade
badly). If the maximum velocity is very high, the deceleration has to start
much earlier and more of the airfoil's lee side has to be devoted to it. If
the deceleration is started later, then the maximum velocity can't be as
high, but the high speed/low pressure can extend over more of the surface
and less of the surface has to be spent on the deceleration. Naturally,
there's an optimum combination of the two which results in milking as much
lift out of the lee side as you can get at a given Reynolds number. This is
important for the interplay between main and jib. But put that aside for
the moment and consider slot effect.

Here's what Smith says about slot effect:

"A remark about the action of slots comes from a recent NASA report: 'It is
well recognized that the usual function of the slot is that of a
boundary-layer control device permitting highly adverse upper surface
pressure gradients to be sustained without incurring severe separation.
This stabilizing influence results from the injection of the high energy
slot flow into the upper surface boundary layer.' A still more recent NASA
report states, 'This leading-edge slat gives the fluid which passes through
the gap between the slat and the main airfoil a high velocity.
Consequently, a boundary layer which grows on the upper surface of the main
airfoil has more momentum than it would have in the absence of the slat.'

"There are two things wrong with these statements. First of all, the slat
does not give the air in the slot high velocity. If anything, it gives the
air low velocity. Secondly, the air through the slot cannot really be
called high-energy air. All the air outside the actual boundary layers has
the same total head. Properly designed and spaced slats are far enough
apart that each component develops its own boundary layer under the
influence of the main stream, and there is no merging within the slot.
Topologically, the process of boundary-layer development is no different
from that on a biplane. Subject to their particular pressure distributions,
the two boundary layers on a biplane grow, trail off downstream, diffuse,
and finally merge. That is just the process for an airfoil system of two or
more elements so long as merging does not occur within the slot.

"The next paragraphs will elaborate on and confirm what we have just said.
There appear to be five primary effects of gaps, and here we speak of
properly designed aerodynamic slots.
"1) Slat effect - in the vicinity of the leading edge of a downstream
element, the velocities due to circulation on a forward element, for
example, a slat, run counter to the velocities on the downstream element and
so reduce pressure peaks on the downstream element.
"2) Circulation effect - in turn, the downstream element causes the trailing
edge of the adjacent upstream element to be in a region of high velocity
that is inclined to the mean line at the rear of the forward element. Such
flow inclination induces considerably greater circulation on the forward
element.
"3) Dumping effect - because the trailing edge of a forward element is in a
region of velocity appreciably higher than freestream, the boundary layer
"dumps" at a high velocity. The higher discharge velocity relieves the
pressure rise impressed on the boundary layer, thus alleviating separation
problems or permitting increased lift.
"4) Off-the-surface pressure recovery - the boundary layer from forward
elements is dumped at velocities appreciably higher than freestream. The
final deceleration to freestream velocity is done in an efficient manner.
The deceleration of the wake occurs out of contact with a wall. Such a
method is more effective than the best possible deceleration in contact with
a wall.
"5) Fresh boundary-layer effect - each new element starts out with a fresh
boundary layer at its leading edge. Thin boundary layers can withstand
stronger adverse gradients than thick ones."

Smith then goes on to discuss each one of the effects in more detail. The
fresh boundary layer effect is typically the only one people mention. The
dumping and circulation effects are responsible for the observation that a
jib is more effective per area than a main. The slat effect is important in
dealing with the flow around the mast.

> Brian again: THEN WHY do we continue to make the mainsail bigger than the
>jib???


Just because the circulation effect causes the jib to produce more lift on a
per area basis does not necessarily mean that the entire system would be
more effective if the jib were made larger than the main. The jib and main
can play different roles and the relative importance of each of the five
factors above are different for each.

For example, consider a genoa with significant overlap. At the location of
the genoa trailing edge, the flow around the main, in the absence of the
jib, is substantially parallel to the trailing edge of the genoa. This
means the circulation effect is not as important. The circulation effect
can be likened to an increase in the angle of attack, because the presence
of the downstream element and the angle of attack both increase the
component of the flow normal to the trailing edge. This requires a larger
circulation around the jib in order to balance the conditions there,
resulting in more lift on the jib. With the large overlap, there's not much
lateral component applied to the genoa's leech.

But the dumping velocity effect is very important. The main doesn't produce
the sharp leading edge pressure peak of a thin airfoil because the peak is
blunted by separation behind the mast. So putting the trailing edge of the
genoa back where the highest velocity occurs maximizes the velocity at the
trailing edge of the genoa. Since the trailing edge velocity is higher, the
jib can carry a higher velocity farther aft on the lee side than it would
otherwise.
To go back to the braking metaphor, it's like the genoa's
boundary layer only has to slow down for a yellow light, but not come to a
full stop, so the braking can start later.

For a non-overlapping jib, the situation is different. The mast and main
cause a considerable lateral component at the trailing edge of the jib,
enhancing the circulation effect. The dumping velocity is still important
for the non-overlapping jib, too.

Now sailboats have to operate at a wide range of Reynolds numbers. To get a
rough idea of the Reynolds number, take the wind speed in knots, multiply by
the chord in feet, and multiply that by 10,000. So a 5 ft chord in a 5 kt
wind is operating at a Reynolds number on the order of 250,000. At that
Reynolds number, it takes a long ways for the flow to slow down to the
sub-freestream velocity at the leech of the main. A laminar boundary layer
can't do it at all in the length of the chord - so laminar separation will
definitely occur, hopefully with reattachment to form a laminar separation
bubble and turbulent boundary layer (most likely just behind the mast).

But the point is, pretty much the entire lee side of the main is fully
engaged in decelerating the flow in light wind/low Reynolds number
conditions. The shorter the main, the lower the maximum velocity on it can
be. That means a lower dumping velocity for the jib, too, so more of the
pressure recovery has to be done on the jib, which cuts into its lift
production. Is it better to have a short highly-loaded jib with high
dumping velocity and large main with a long pressure recovery and more
off-surface jib pressure recovery? Or is it better to have a large jib,
with less loading and lower dumping velocity, and a shorter main to finish
up the job? It's not a slam-dunk decision either way.


I've not tried to design main/jib combinations, but I have looked at rigid
wing/slotted flap configurations. The data are on my web site. I
considered flap sizes from 20% of the total chord to 50% of the total chord.
Especially in the light wind conditions, the bigger flap (hence bigger main)
was more effective. The 50/50 combination only starts to get into the
genoa/main range, and I didn't look at anything like a slat/wing combo which
would be more representative of a jib/main. But the trend did not point to
a larger forward element being the better choice.

I would love to be able to look at this issue with the proper tools.
Unfortunately, the only programs I have for multiple elements can't handle
separation, so they can't predict maximum lift or the onset of the drag rise
due to stall. I had to do some really crude fudging to guess at stall
effects. It would take something like MSES to calculate the two-dimensional
flow around main and jib (with boundary layer), and that program is out of
my price range. I've asked Drela about a multiple-element XFOIL, and he's
thought about it but hasn't pursued it.

The bottom line is that the jib can act as a slat for the main, in which
case a small jib makes sense. The main can act as a slotted flap for the
jib, in which case a large jib makes sense. Deciding between these two
extremes is a quantitative issue that can be answered with experience on the
water, wind tunnel test, or computational methods. Each has its strengths
and drawbacks.
Cheers,
Tom Speer

 

 

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Not all sail area is the same.

Nearly all the propulsive force comes from the leading edge. The length of the luff, not the LP, dominates.

If there were no rating or measurement rules, you would see maximum leading edge, minimum LP: the higher the aspect ratio, the better.

Since stability also matters, and infinite aspect ratio means infinite height of he center of lift which means infinite stability is required, we need to find a nice compromise. This is generally true in engineering and yacht design in particular.

A common compromise is to use multiple sails.

A foiling kite can use a single high aspect foil. An A class too: in both cases, little total SA is needed or allowed compared to the righting moment (infinite and very high).

Once lead, lots of crew, and/or substantial structure is required to provide stability, then it pays to reduce the lever arm of the rig to reduce the required stability. The age old way of attacking the problem is to use multiple sails, and sometimes multiple spars, to provide lots of leading edge for a given amount of stability required. Hence jibs, multiple jibs, schooners, and so on.

As mentioned above, the Genoa was simply a way to gain a little advantage under the rules. It is certainly an inefficient way to use expensive sail cloth!!

Yachting is and has always been dominated by fashion: life is too short to sail an ugly boat.

Engineering areas where lots of money and time is spent to discover efficient (minimum material and structural properties of those materials) ways of generating high lift to drag includes the turbines of aircraft engines, hydroelectric plants, steam turbines, windmills for water wells, wind generators, ship and airplane propellers.

In these areas, overlapping foils are never seen.

When somehing forces the foils to be close, they still do not overlap. The best configuration for minimum distance foils is to have the leech of the jib at the minimum pressure curve of the mainsail, which is about 30 to 45 degrees forward of the beam at the mast.

It's not that the overlap has no value, it's that it's much, much less helpful area than if it did not overlap. That is why going from a 155% to a 95% can help going to windward (maximize lift to drag) long before it's a stability problem.

Sorry for bringing actual information into these forums, but I don't have any pictures of my wife's tits on this iPhone.

We just bought our new boat last year and all but one of the sails were blown out after 20 plus years. We are not racers and concluded that we did not want an overlapping head sail. Both sailmakers we talked to thought we were crazy, we finally went with a main and 95% jib from Quantum. Lars (the professor) at the S&S Owners forum has been recommending smaller headsails for a long time. I cannot remember his exact quote, but essentially, dropping from a 160 to a 120 Genoa only costs .25 to .5 knots.

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What I'd like to understand is that when the leech of the jib is arrayed just in from of the mast, where the main pressure distribution is least, that implies that the velocity at the jib leech is pretty slow (to meet the Kutta condition), which means the low pressure flow across the jib is stressed more, which means it's more likely to break and not reattach.

 

contrast that with Gentry's idea that if the jib leech is arrayed at the point of the main where pressure distribution is highest (and low pressure flow is fastest), the Kutta condition would seem to dictate that the jib's low pressure flow is less stressed, which would mean more reattached turbulent flow.

 

So, is a blade jib with a more stressed low pressure flow inherently more powerful than a bigger jib with a lesser stressed low pressure flow? Less friction? It seems Reynolds Number effects aren't helping either.

 

It seems to me the less stressed flow can sustain more camber, or with less camber, lower drag. Which kind of begs favorable l/d ratios? Or is friction a bigger deal? It seems that Reynolds number effects would help here.

 

That said, for 4k TW up, I use a 95% 3/4 jib on Amati. Belief? And a 165% drifter for low wind and off the wind. Old School stubbornness?

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Well then you might have a look at this study where the dbl-jib with overlap outperformed the sloop rig, and the dbl-jib arrangement without overlap.

WIND TUNNEL AND CFD INVESTIGATION OF UNCONVENTIONAL RIGS

http://forums.sailinganarchy.com/index.php?showtopic=175973&p=5420278

And this was a pretty sophisticated study .

 

 

 

 

 

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But it kind of avoids a question that turbine research has studied- where is an external spar best deployed? (~like a mast)

 

The best result was with the spar on the high pressure side, 33-50% from the leading edge.

 

Which is where a 'normal' mast would be with no mainsail and what would be considered an overlapping jib- say 180-200%

 

Would such a setup benefit from system rotation amped up by the mast? And give the jib lift?

 

Bluff body aero would kind of support this over an aft A frame?

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I dunno about all this theoretical back-and-forth but I can relate from personal experience, having crewed for a few years on Gerry Driscoll's S&S 39 "Nova" out of SDYC, that the 195% CCA Genoa was an absolute beast to tack, and we were one of the great rule beaters of all time in So-Cal light-to-moderate air. On tyhe other hand, we tried to defend the Lipton Cup for SDYC once in 20+ knots, and that disn't go very well :-)

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I dunno about all this theoretical back-and-forth but I can relate from personal experience, having crewed for a few years on Gerry Driscoll's S&S 39 "Nova" out of SDYC, that the 195% CCA Genoa was an absolute beast to tack, and we were one of the great rule beaters of all time in So-Cal light-to-moderate air. On tyhe other hand, we tried to defend the Lipton Cup for SDYC once in 20+ knots, and that disn't go very well :-)

Sort of addresses my old contention that it was very often that the handicap rules were often designing our rigs rather than mother ocean.

 

I agree that those very big overlapping genoas were not that great of an idea for all-around usefulness on our sailboats. And uni-rigs do perform very well in many cases (sort of isolated to pure up-wind capability). But there are many tests and practical experiences that indicate a moderate overlap by the genoa is a very practical sail.

 

The genoa I propose on my mast-aft rig looks to be a pretty big overlap, but in reality is only 104% as measure by the old standards.

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The early iterations of IOR penalized mainsail area harshly, and jib/genoa area much less. That is why the early IOR boats like the Ericson 39s and Ranger 37s had tiny mains, and huge masthead genoas. Over time, the situation moderated, and larger mains became more fashionable. By the mid-1980s, this penalty situation had been corrected, and boats could be designed with fractional or masthead jibs, at the option of the designer. It was generally thought that fractional inventories were less expensive to maintain because the mainsail was the only large sail in the inventory. At present, we see a big shift toward non-overlapping jibs in classes like the TP 52s. One reason for this is that they use athwart-ships jib leads, so the jib sheet can be moved in-board to reduce the angle of incidence of the headsail, which makes the boats closer-winded. Of course, those boats compensate for reduced sail area by using masthead genoas, and Code 0s to add reaching sail area.

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The early iterations of IOR penalized mainsail area harshly, and jib/genoa area much less. That is why the early IOR boats like the Ericson 39s and Ranger 37s had tiny mains, and huge masthead genoas. Over time, the situation moderated, and larger mains became more fashionable. By the mid-1980s, this penalty situation had been corrected, and boats could be designed with fractional or masthead jibs, at the option of the designer. It was generally thought that fractional inventories were less expensive to maintain because the mainsail was the only large sail in the inventory. At present, we see a big shift toward non-overlapping jibs in classes like the TP 52s. One reason for this is that they use athwart-ships jib leads, so the jib sheet can be moved in-board to reduce the angle of incidence of the headsail, which makes the boats closer-winded. Of course, those boats compensate for reduced sail area by using masthead genoas, and Code 0s to add reaching sail area.

FWIW, our general goal with Amati was to use the big sails in light air, when they're easy to handle. It's worked out really well. But I think you need a boat with a DLR under 105 (we are~ 100 ) or so to make it work, at least emotionally. Planing really makes the concept work. I think with a heavier boat, the temptation to go just a little faster gets overwhelming.

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  • 2 weeks later...

 

8mr still use rather large genoa's as well. even the modern

On six meters the LP is J+ 3 Meters.....

 

 

So a rating anomaly then?

 

I think it's safe to say, for the most part, Boats that are rated on actual area, ie most modern race boats, will tend to have little or no overlap. Boats where the rating gifts an overlap, including boats with no rating considerations, ie cruisers, "vintage" rules like the meter and meter square boats, may see genoas develop. Sure not the best for windward work, but won't hurt on any other angle...

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8mr still use rather large genoa's as well. even the modern

s82d17f_047e4a00a724491f80a2a143d04f8c66.

On six meters the LP is J+ 3 Meters.....

 

I sailed this last month, loved every minute of it... It should be close to 180%.

 

Regata-Illas-Atl%C3%A1nticas-2016-82.jpg

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