Why does a cutter rig point higher & sail faster?

[SeaDrive]

Originally Posted by gybeset

... rake is faster and still is in a few specific cases (Contender, Hobie 16,49er)

I doubt the weight of the light masts is a factor in these boats. More important would be that the smaller angle between stay and mast increases the tension due to the pull of the leech and mainsheet.

dreamer: Thanks for the explanation and the picture. I suspect the fastest way to get your boat downwind would be with a convertional spinnaker, but it seems clear you don't want the trouble. Neither would I. Cruisers don't need to race. Beautiful boat.

[MikeJohns]

Originally Posted by dionysis

Remember that aerodynamically, rake reduces forward thrust as the cosine of the angle.

The reduction factor will be a factor of (1- [cos(rake angle)]) which doesn't amount to much, for example at 7 degrees its about 0.0075 less.

[gybeset]

Originally Posted by Rich Kinard

We can point higher (10+ degress) and sail faster in light winds (up to 80% of true wind speed!), after converting our O'Day 37 to the cutter rig version. I fly a 110% high clewed Yankee and 75% Staysail.

Can anyone explain this phenomenon or share their similar experiences?

Phenomenon could be just the word for it , seriously tho the most CURRENT opinion we could seek here (particularly for a conventional leadbelly) would be from the skippers or designers of the Global Challenge 72ft Cutters that just departed NZ for Sydney

[brian eiland]

Originally Posted by skinny boy

Ah, most racing boats I know have rake and pre-bend making them anything but vertical. The fastest boats around these parts have more rake than the others like it. My rig carries a couple of degrees of rake and used to have more until I got my new sails. Pulling the mast back a bit increases my boat's pointing ability and every other boat I have been on. Standing the rig up even leaning it forward a bit helps off the wind to project more area.

How about this sampling from Ron Holland.

[Alan Hugenot]

The answer to the original question of why will a cutter points higher than a sloop used to be common knowledge, normally acquired in the first year at sea by every working sailor.

Sometimes we all make the mistake of thinking that what we know is all there is to know. But, the truth is that racing sail has become so narrowly sloop oriented that the collective wisdom of the "powers that be" within the racing world have forgotten, or never even learned, much of what used to be common knowledge among ordinary working sailors.

Back in the days when cargo was moved by sail, no one set a Genoa nor a Spinnaker. Spinnakers are much less efficient than square sails, and Genoas are much less efficient than a schooner's "fisherman" sail. Indeed those two sloop sails are merely strange anomallies invented to help the inefficient sloop rig try to preform as well as a cutter, ketch or schooner. Actually, the only reason sloops dominate the racing circuit is because they are easier to understand, cheaper to build, and novice sailors can master their simplicity sooner, so there are today thousands of sloops and very few cutters, ketches, and schooners (I left Yawls out of the list because they are merely sloops with a mizzen tacked on).

Just 100 years ago the great ocean cargo ships, dependent on the wind, needed to point as high as possible and sail downwind as fast as possible, and they all used multiple headsails. And if they had needed genoas or spinnakers they would have invented them.

Unfortunately, the experience of most racing sail participants is limited entirely to sloops racing around windward and leeward marks. They simply have no intuitive gnosis outside the sloop's foretriangle (translate "can't think outside the box")

The slot effect is a well known principle of sail dynamics. It is a simple fact that the slot formed between a jib and the mainsail improves the apparent wind for the succeeding sail, a 150% genoa elongages the slot but the overlap does not have much effect on improving the apparent wind, any more than a 100% jib. However, it does improve boat speed on a spring reach. However, a succession of several slots as in the case with multiple head sails it improves the apparent wind for each following sail, with the result that a cutter can point much higher than a sloop. Just as a sloop can point higher than a cat rigged dinghy. A staysail schooner with two flying jibs forward of the staysail can likewise point higher than a cutter. This was common knowledge of all sailors for hundreds of years. But, today it is unfortunately not known by the rules committees, all of whom have never experienced this phenomena because sailing cutter headed rigs is simply outside their experience.

a quarter century ago, I used to win every race and take the championship trophy in all the PHRF handicapped races, because there the PHRF rules did not take into account my staysail. The rule writers were simply unable to conceive that just by setting the staysail inside the genoa I had doubled my leading edge, created a second slot and improved the apparent wind angle for the main. I checked the PHRM No FLying Sail rule, and it still allows me to fly a staysail inside the jib with no penalty, so long as my vessel is normally rigged with a permanent stay for the staysail. This also allows me to rig the staysail inside my downwind spinnaker on a spinnaker reach, instead of carrying an asymetrical tri-radial. This improves my boat speed by around 50% on that reach, and while my fellow competitors are penalized for carrying their tri-radials, I am not. They end up owing me time, when I have the clearly faster boat.

The fact that multiple head sails allow a boat to point higher was common knowledge among working sailors who sailed their ships every day with no engines and lived aboard year round. Today, most racing sailors are lucky to get four days of sailing in per month for 9 months of the year. Which only amounts to 36 days a year, so it takes them 12 years to acquire the experience in sail that any apprentice deck hand would pick up in one year sailing a ship at sea. Yet, today most of our sailing instructors become certified "experts" with less than three years of part time sailing behind them. Consequently, since the teachers don't know about multiple head sails, improved apparent wind, slot effects and increased leading edge, how can we expect the students to know about such things.

To me it is amazing that experienced folks from racing sail, will question these long proven physical principles, simply because it is outside their experience. And, yet they won't take the time to research the subject which their avocation depends upon, even though they can find time to watch the super bowl. Instead they accept the "received" wisdom on the docks, which is that the sloop is the finest possible rig for racing sail. Have they also forgotten that the original Yacht "America", which was designed for speed, and which took the America's cup home to the New York Yacht Club was a cutter headed schooner? They probably did not realize that the ownere had experimented with several other rigs on this hull before desciding that a cutter headed schooner rig was fastest?

Alan Hugenot
Naval Architect & Licensed Master in Sail
Retired Collegiate Racing Sail Coach
Certified Coastal Cruising Instructor A.S.A.

[dreamer]

yeah!

wow, that was great and it really helps explain why our boat was not as much of a dog as I expected it to be. Even Bob Perry poo-pooed the cutter rig on our boat (his design). But I think he too, as the others you mentioned, may have simply forgotten what a great combination these sails are.

I suspect you hit the #1 reason why sloops dominate: ease of use. I've had seasoned sailors (well, at least 72 days of sailing ) on our boat and they were confused by the whole thing. I would suspect that a racing crew would see the extra set of lines a nuisance.

[amolitor]

Then why do windsurfers (cat rigged, note) point higher than just about anything else?

Also, if someone could explain current thinking on 'slot effect' I'd appreciate it. It's my impression that the theories of 20 years ago on it have been pretty thoroughly debunked, and that there are now new theories about it. I didn't really understand either one, so I don't know which is which

[dreamer]

Windsurfer doesn't count...not a displacement hull. C,E, and M scows can also point higher. Again, not a displacement hull.

[gggGuest]

> Just 100 years ago the great ocean cargo ships, dependent on the wind, needed to
> point as high as possible and sail downwind as fast as possible, and they all used
> multiple headsails. And if they had needed genoas or spinnakers they would have
> invented them

You don't think the limitations of the materials and equipment they had might just have been a very small factor in this?

[amolitor]

Could you explain why non-displacement hulls don't count?

Cat rigs have the property that you can sheet them clean across the boat. Sloops and cutters can't bring the headsail(s) in even to the mast. On a cat rig, if you've got sail shape to keep the lift forward of the beam, and enough fin/keel in the water to keep you from crabbing too much, you can point like crazy.

The only relevance of non-displacement hulls that I can see if that they go fast, so your fin(s) can generate tons of lift without stalling.

Anyways, still not seeing any credible argument that cutter rigs inherently point higher than sloops, and I am nearly certain that cat rigs "inherently point higher" than either of the others, whatever that means. They're less efficient, so aren't as good at anything else.

They ran out of time. Steam powered boats were begining to appear on the ocean. Hi-tech of the day did them in. What is the speed of the Tall Ships in the present day?

[CT 249]

"the truth is that racing sail has become so narrowly sloop oriented that the collective wisdom of the "powers that be" within the racing world have forgotten, or never even learned, much of what used to be common knowledge among ordinary working sailors."

I beg to differ, because your facts are wrong. The twin-headsail rig was used commonly in the '70s FOR CLOSE REACHING. Sailors like Dennis Connor and John Bertrand used them BUT ONLY FOR CLOSE REACHING. They were perfectly aware of twin headsail rigs but they knew they were not as effective upwind.

In the late '60s/very early '70s twin head rigs were used upwind in heavy air in Australia, but as soon as sailcloth improved and larger single headsails could be built and retain their shape, the twin head rig was relegated to reaching.

Later, the Whitbread maxi ketch Stienlager set twin headsails, main, mizzen and mizzen staysail so they were completely aware of importance of the slots, as was Farr who designed it and remains the top designer in the world. Yes Stienlager used them only FOR CLOSE REACHING, not upwind.

Almost every good middle-aged offshore sailor has had experience with twin headsails, thanks very much. The skippers of many of Australia's top boats (Ragamuffin, Challenge) were leaders in the twin headsail area; they know about it very well.

Nigel Irens is very innovative and very aware of older craft, hence his designs for gaff and lugger styles (which he sails himself). His tris are not constrained by rules yet they are sloops. Why? 'Cause it's faster.

"those two sloop sails are merely strange anomallies invented to help the inefficient sloop rig try to preform as well as a cutter, ketch or schooner."

So why did old rules like the CCA have a rig allowance that rated a schooner rig as something like 90% of a sloop, and a ketch about 94% of a sloop?

Why do current rules give much lower ratings to ketches, yawls and schooners? The IOR Mk IIII rated the mizzen at only 1/3rd of its actual area (Shape f Speed p 267 and many, many other sources) and did not count mizzen staysails at all. Mk IIIA had even "cheaper" sail area in the mizzen.

So the IOR rated a ketch with about 1000 ft of upwind sail at about the same as a sloop with 866 ft2, YET THE SLOOPS WERE NORMALLY FASTER...lots of people in '88/'90 looked at doing ketches for short courses because of this favourable treatment - yet they only worked in the Whitbread when other factors (machine measurement, Mk IIIA and heavy boats etc) also had major effects.

Lots of people looked long and hard at ketches at that time but they realised that EVEN WITH FREE SAIL AREA they were slower around most courses.


"Actually, the only reason sloops dominate the racing circuit is because they are easier to understand, cheaper to build, and novice sailors can master their simplicity sooner"

What? Pros race winged and canting keel water ballasted carbon fibre boats with Code Os and runners and they are worried about simplicity? Yeah, right.....

So why don't cat rigs rule, by the way?


"Just 100 years ago the great ocean cargo ships, dependent on the wind, needed to point as high as possible and sail downwind as fast as possible, and they all used multiple headsails. And if they had needed genoas or spinnakers they would have invented them."

And just 100 years ago the great steam ships and railway engines needed to develop as much power and speed as possible when hauling trains and cargo, and they used steam reciprocating engines. And if they had needed turbines, diesels and electricity, they would have invented them.

No, Uffa Fox and other contemporary accounts record that as sailmaking technology advanced, the number of headsails was reduced because one big sail was faster. Look at the J class and you'll see the number of headsails was reduced from 3 to 1 as sailmaking improved. It's damn simple, it's there in the pics and the plans.

The reason for multiple headsails is well known - those sails are terribly heavy and hard to handle and there's no way the comparatively small crews could have set and worked a single massive headsail.


"Unfortunately, the experience of most racing sail participants is limited entirely to sloops racing around windward and leeward marks. They simply have no intuitive gnosis outside the sloop's foretriangle (translate "can't think outside the box")"

It depends where you come from. Some of us have raced gaff ketches, sailed schooners, etc. Many of the top skiff sailors regularly race the old gaff skiffs. Some of us race long distance. Most of the top Australian big-boat owners have experience in other rigs (at least one sails a gaffer, one formerly owned the 23 metre Cambria which started off life as a multiple headsail boat and was for a long time a ketch) yet they all sail sloops. Why? "Cause it's faster.

For a start, the most common boats sailed by top-level sailors are the Optimist (sprit cat) and the Laser (cat). This is demonstrated by records on the Oppie site and other places. So once again your facts are wrong.

"The slot effect is a well known principle of sail dynamics. It is a simple fact that the slot formed between a jib and the mainsail improves the apparent wind for the succeeding sail, '

Hmmm, ask Arvel Gentry about that one.

"Today, most racing sailors are lucky to get four days of sailing in per month for 9 months of the year. "

But what about those who sail 300+ days per year while in AC and Volvo and other campaigns? The ones who I know who do such sailing are well in touch with their heritage; the family spe******es in rebuilding classic boats when not sailing in things like the Olympics and AC. Yet they sail sloops, racing and cruising...

"Have they also forgotten that the original Yacht "America", which was designed for speed, and which took the America's cup home to the New York Yacht Club was a cutter headed schooner?"

Yes, and that was in the 19th century. Saying that we shoould still look to "America" for our designs is like saying that the current Mercedes Formula 1 team should look to Benz' 19th century car for design clues, or that modern aircraft should be a biplane because biplanes dominated early flying.

"They probably did not realize that the ownere had experimented with several other rigs on this hull before desciding that a cutter headed schooner rig was fastest?"

Well, that's fairly well hidden history AFAIK. Can you provide sources?

"America" did not actually beat one of the syndicate's previous boats as demanded before the full price was paid. In fact, IIRC, Steer WAS paid the full price - but I think the cutter "Magic" (oowned by Stephens, syndicate head) beat America in NY tests. In the actual AC itself, the little cutter Aurora (much smaller boat) came home fast and would have beaten America under any rating system - but it was merely first home for hte Cup.

Why not read Alf Loomis' 1940s book "Ocean Racing" and read how the Malabars and other schooners, despite their low rating, were defeated by the sloops and yawls as ocean racing developed?

Multiple sails are -were a fact then, because getting the goods to port safely after being demasted in a storm, was most important. Lose sails, still have 2 or 3 to make port. Same for warships then. Racing has few restraints.--------------I remember also about the selection of America over a better boat.

[brian eiland]

Originally Posted by amolitor

...Also, if someone could explain current thinking on 'slot effect' I'd appreciate it. It's my impression that the theories of 20 years ago on it have been pretty thoroughly debunked, and that there are now new theories about it. I didn't really understand either one, so I don't know which is which

Have a look here using the 'search tool' for this forum (handy item!)
Sail Aerodynamics and the Slot Effect

[amolitor]

Yeah, I re-read THIS thread and found an earlier cite of THAT thread and read it. Alas, after I posted here

Thanks!