Jib Sizes

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jaydog5000

Couls someone explain the Jib sizes. 150%? 140%? and when they should be used?
 

Alan

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Jun 2, 2004
4,174
Hunter 35.5 LI, NY
The jib size as expressed as a percent is found by dividing the "LP"(luff perpendicular) by the "J"(distance from the front of the mast to headstay along the deck) dimension for that particular boat. For example if the LP was 15' and the J was 10' then 15/10= 1.5. Multiply by 100 to get the percent 1.5 x 100= 150% In general the larger sizes are used in the lighter winds. As the wind strength increases the size of the jib is reduced. Different boats can handle wind increases with varying amounts of sail area.
 
Jun 2, 2004
1,438
Oday 25 pittsburgh
Jaydog, The 150 and 140 refer to the jib size.

A 100% jib fills the area between the mast and the forestay. With that in mind, a 150 is a jib that is 50% bigger than what the 100% covers. The reason for different size sails is the need to capture different amounts of wind for the boat to perform to it's max in a given wind. Sailboats have a max performance.Too much sail overpowers the boat and causes problems. In light winds, you need as much sail up that will shape in a performance producing sail. A large sail like a drifter made of 1.5 oz. nylon in very light wind will shape much better than a heavier say 6oz dacron 150 of the same size. The sails can be the same size but it is the shape that counts in light wind. As the wind picks up the light sail is not strong enough to perform with out damage to the sail. Now the 6 oz. dacron is the better sail. If the wind picks up more and the boat is heeling too much and the steering is uncontrolable, a smaller sail is needed. Say a 100% jib. This will remove much of the heeling and and still put the need powr into the boat. The boat only goes so fast. When the boat creates a wave from bow to stern, that is the designed hull speed. For constant terms, this is hull speed and the boat will not go faster. It is best to use the smallest sail you have tokeep a constant max hull speed. When you use larger sails, it does not make the boat go faster and the steering of the boat will be overwelmed so that control is difficult. OK,that was probably to much at one time. I will stop and if you have questions, ask again. r.w.landau
 
B

Bob B.

Jaydog. In additon to Alan's info.

I'm thinking that "LP" may not be a familiar term to you. On the C22 sail drawing notice that the 150% Genoa drawing indicates an LP of 12'. The C22 has a "J" of 8'. (12' divided by 8' X 100=150%) Regards from Canada.
 
P

Phil

To-may-to, To-mah-to

I've heard both descriptions before. LP/J is a precise measure used in class designations for racing. Can anyone give the history of the percentage of the foretriangle area description or the connection to jib size by number rather than overlap?
 
Feb 26, 2004
22,929
Catalina 34 224 Maple Bay, BC, Canada
It's not overlap

it's just the trigonometry of the luff perpendicular dimension.
 
Jun 12, 2004
1,181
Allied Mistress 39 Ketch Kemah,Tx.
RW Landau has it right...for now

When someone asks a question, such as Jay did about what is a 150 or a 140, it should be fairly obvious that he is brand new to sailing and if he knew what an LP or a J was, then he probably would know what a 150 is.It totally amazes me how some people can over complicate the easiest things. So , if A 100% jib fills the area between the mast and the forestay, then a 150 goes back another 50% past the mast....more or less. That should give you a rough idea, although not quite technically correct. The things that make people like Carl Sagen and Steven Hawkin famous is` their ability to explain the most complicated structures known ( from the atom to the universe) to mankind at a level that is easily understood by all, even at the risk of being slightly technically incorrect.
 
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J

Joe

here's the score....

sailortony, rw landau, phil... wrong Alan, Moody, Stu, Bob B.... right Alan's answer is all that is needed... it's just a way of relating a sail's size to its boat. Has nothing to do with overlap, or foretriangle. It's simple geometry...not trigonometry, God Forbid. If you don't beleive me... go ask a sailmaker.
 

Alan

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Jun 2, 2004
4,174
Hunter 35.5 LI, NY
One small mistake...

... that many skippers make. The #3 sail with a 100% rating is, in fact, an overlapping sail. To have a 100% rating, the LP(or height of the triangle) must be equal to the "J" for that particular boat. This then would require the clew to extend past the mast, therefore an overlapping sail. A true non-overlapping sail would need to be on the order of 90% where the LP is less than J. This, of course, has nothing to do with sailing. It is simply a mathematical misconception that many have.
 
K

Kris

Oh Jaydog...

You got'em goen good with that one. Its fun to watch 'em out brain each other. Your queston has been answered, but can you guess what it is? You know the bigger the percentage, the bigger the sail. A jib usually comes back to the mast, or so. That is basicly 100%. You want more power? You want more sail. But, you can over do it. Those cool looken boats that are almost covered in foresail, from front to 3/4 back or so, that would be the 150. OR SO. I want a big ol 150, but its probably not the right move for my tender h23. So maybe 130. I'll ask the shop guy, he has a 23 also. Do the same if you can.
 
Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
A 1, and A 2 and A 3

The sails by the numbers, ie "get the #2 genny out" are just the racer way of describing their sail inventory. The #1 is the biggest #2 is the next one down in size etc. There is no correlation between a #1 and any percentage size. For instance if you had only one jib then that would be your #1 no mater how big/small it was. The use of additional adjectives, #3 lapper, #2 genny, #4 Yankee, are from sailing history where each sail actually had a name. This used to be a "(make)Hard and Fast" rule but alas we have all been sidetracked by the land lubbers inability to assimilate our language. Alas gone are the days of the Topsail, the Cloud Botherer, the Moonraker, and the Angele tickler. For an atta-boy and the "knows his/her salty stuff" award for the day, who can tell me what those last four sails have in common and how they got their names?
 
P

Phil

Rules and design tug of war

Thanks Moody and Bill. I'd sure like to see a picture of some of those 150% non-overlapping sails that have been inferred. Maybe they have mains that don't come up to the mast. :) I guess geometric ratios would have been more appropriate than "overlap". I agree that overlap of the sails does not define area. Consider this, if you compare the area of a decksweeper with LP = 1.5*J, its area is not 150% of the foretriangle area. Conversely, a decksweeper with area 150% of the foretriangle area does not have LP = 1.5*J. I have heard both descriptions used though, and I wonder if the area ratio is just an old convention or even approximation (better or worse depending on the angle between the forestay and deck). Is the LP/J calculation a more recent description originally stated as an attempt to clarify class rules, or as you suggest perhaps impact design? I don't know the history that well but it seems that design always pushes the rules, the rules adjust to make for better competition, and it all repeats. Just some thoughts.
 

higgs

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Aug 24, 2005
3,701
Nassau 34 Olcott, NY
with trepidition...

This came up a few months ago and I answered much like landua, which , unless you are racing, suffices perfectly. I got raked over the coals by the experts that keep their sailing encylcopedias at their computer desk. Trust me and landau - his answer will get you where you are going - unless you are a serious racer, which I am beting you are not. In light air use the 150 or the biggest jib you have. If the wind kicks up and the boat begins to be hard to handle it is time to either put in a reef or reduce headsail to 120 or 100 or whatever you have. A little trial and error and you will know what is best for you and your boat. It ain't rocket science.
 
Oct 25, 2005
735
Catalina 30 Banderas Bay, Mexico
Phil is right.

A sail with LP 150% of J has more than 150% of the foretriangle area. I=41 J=13.2 Area = 41 x 13.2 x .5 = 270.6 sq ft = 100% Foretriangle Area The I dimension is the leech, the J dimension is the foot. Good old Pythagoras tells us the luff must be 43.0725. If LP = 150% of J, LP = 19.8 Using the formula Base x Height x .5 = Area Base is the luff length = 43.0725 Height is the LP = 19.8 43.0725 x 19.8 = 426.42 270.6 x 150% = 405.9 The confusion comes from the fact that a jib that fills 100% of the foretriangle does not have an LP = J. In this example the LP is only 12.57 or 95.2% of J. If you compare jibs by LP the 100% jib has area = to luff x J x .5 not I x J x .5 Thus a 100% LP jib has area = 284.28 and the 150% LP sail at 426.42 is indeed 150% of the area of the "100%" jib. As Alan said a 100% LP jib overlaps the mast. A 100% foretriangle area jib might or might not overlap the mast, depending on the height of the clew. As long as you are consistent, it makes sense. My boat is pretty dull, it has no idea what area the sails are, only if there is not enough or too much. The only people that care about the actual dimensions are rating committees. :) If your boat is slow, you need more power (area + trim). If your beer slides off the seat and spills in the cockpit, you need less power (area + trim). :) Topsail, the Cloud Botherer, the Moonraker, and the Angele tickler. Are all names for the highest sail on the mast at one time. Topsails can be square or fore and aft. Moonrakers or Moon Sails only refer to the highest sail on a square rigged mast (above the Royal and Sky Sails)?
 
J

Joe

the point is, higgs

...that someone asked a question about jib sizes... whether he races or not he deserves an accurate answer, not a prejudiced opinion.
 
Sep 24, 1999
1,511
Hunter H46LE Sausalito
I don't agree...

...with Bill's claim that the numbers refer only to the boat's inventory. I used to race in a class (Express 37) that outlawed #2s in an attempt to keep the inventory down. Still, a number 3 was called a number 3 even though we didn't have a number 2 aboard. The whole thing was supposed to keep the cost of racing down, but it backfired because those of us who could afford it would sail with a standard #1, a "heavy" #1 that was cut flatter and therefore performed like a #2, and a #3. In essence, we ended up paying more for the sail inventory than if we'd had a traditional 1,2,3 suit of sails.
 

higgs

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Aug 24, 2005
3,701
Nassau 34 Olcott, NY
Joe:

All the number are fine, and it is good to know how the sail is measured, but if one doesn't know what those numbers mean once your boat is out on the water, what good are they? Hell, I don't even know for sure whether my jib, that came with the boat, is 140, or a 150 and for my uses it doesn't matter. Jaydog may need a perspective like mine just as much - or even more - than he needs all the formulas. Why not let him sort it out?
 
Dec 2, 2003
480
Catalina C-320 Washington, NC
Sails for Sea Salts

A fully rigged, square-rigged mast consists of three "spars": (a.) the "lower mast". (b.) the "top mast". (c.) the "topgallant mast". This rig has three basic sails: (a.) the "course" bent on the lower mast (b.) the "topsail" bent on the topmast (c.) the "topgallant" bent on the topgallant mast. Square riggers often flew a "royal" sail above the topgallant. Clipper ships flew "skysails" above the royals. Some flew a "moonraker" or "moonsail" above the skysail on the mainmast. There are names for sails above the moonsails: heaven poker, angel poker, and cloud disturber, These are refered to in literature and might have existed, but I understand there is scepticism as to their existance by experts in the field and am unaware of documented evidence of their actual use. Apparently "Cloud Botherer" and the "Angele tickler" may have been used as well. Although, the latter sounds more like something purchased out of a coin operated vending machine in a restroom.
 

Joe

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Jun 1, 2004
8,140
Catalina 27 Mission Bay, San Diego
Higgs, I certainly agree

that your perspective regarding practical application is as valuable as anyone's. I do not believe, however, that categorizing the correct answer to a simple question as being only important to "serious racers" unworthy of your considerable sailing experience. What sails you maintain on your boat and whether you classify them by Number, percent, colloquial name, or traditional name may not be important to many people. Truth is, most of the sailors here probably only have a main and a furling headsail, so what's the point? But what is important is that they know there are definitions, methods and traditions in our beautiful sport. It is important, also, that we pass this knowledge on in a responsible, conscientious manner, or at least refer any knowledge seeker to a reliable source of information that will answer his questions unobjectively and correctly. Then....as you so aptly suggest....he can make his decision as to how to use this new found knowledge.
 
Jun 2, 2004
1,438
Oday 25 pittsburgh
You guys, I answered this question like sailortony

said. I realized that Jaydog was probably new to sailing. I gave him info to sort out his questions. Remember, there was more than one question. Now, there have been books written on both subjects. I did not have the time and my guess is Alan didn't either because he only addressed half the question which is what most of the posts have done since. You guys with your sailing notes and instant look-up on line crap, do not take into account the simple questions a new sailor has. When you first started being interested in sailing, would you have perfered a simple answer or a book form responce. By the way, none of you have taken the time to explain in full the answer to Jaydogs question/s. If you are willing to type for day at a time to fully answer a simple question....which I asked if he had more questions, to ask again. (After the responses I would have been afraid to ask because all of you knoweverything people had to be correct, which some of your correctness is still being questioned) Be my guest. Have you heard the story where a young 6 year girl asked her dad about sex? Her dad carefully composed an answer to her question. He sat her down and explained the facts of life for more than an hour. With glared eyes the little girl said, "so dad, which box would I check?" Guys, give a young sailor a chance. Bring them aboard, then if you feel it required, beat them to death with your knowledge! The problem is you guys read responses with critisim in mind and not helpful info. Quit jerking people off and let's try to support the sailing community. Positive info instead of the superior knowledge brain approach. We have not heard back from JayDog. Which we would like to hear from you. Their are many here that want to help. thanks guys, you ran another would be off. Thanks Joe I think you under stand. just a thought... r.w.landau
 
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