I am fairly new to this so bear with me on this one. When a sail is said to be a 110% or 135% genoa what is that a measurement of. Is it percentage of a standard mainsail for that boat ie a 150% genoa is 50% larger that the main? Dave
Genoa percentage
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Headsail percentages
Dave: Headsail sizes, expressed in percentages, are based on: (size of the headsail luff x headsail foot x per cent overlap) divided by 2. Anything over 100 per cent indicates the headsail foot overlaps the distance from the tack of the headsail to the mast, and has nothing at all to do with the size of the main. Hope this helps. We've all been there.
Dave: Headsail sizes, expressed in percentages, are based on: (size of the headsail luff x headsail foot x per cent overlap) divided by 2. Anything over 100 per cent indicates the headsail foot overlaps the distance from the tack of the headsail to the mast, and has nothing at all to do with the size of the main. Hope this helps. We've all been there.
Headsail measurements
Here is a more technical (and precise) explanation. LP Defined The LP or Luff Perpendicular is a measurement used to describe the size of a headsail. The LP measurement is the length of the line perpendicular to the luff that passes through the clew. The percentage of a sail (150%, 135%, 100%) and the J dimension are used to calculate the LP of a given sail. The J dimension is the distance between the forestay intersection with your deck aft to the front of your mast. Calculating your sails LP Example: If a Catalina 30 (standard rig) owner wanted a 130% headsail for his/her sailboat with a J dimension of 11.54', the LP calculation would look like this: 11.54' x 1.3 (130%) = 15.0' LP = 15'
Here is a more technical (and precise) explanation. LP Defined The LP or Luff Perpendicular is a measurement used to describe the size of a headsail. The LP measurement is the length of the line perpendicular to the luff that passes through the clew. The percentage of a sail (150%, 135%, 100%) and the J dimension are used to calculate the LP of a given sail. The J dimension is the distance between the forestay intersection with your deck aft to the front of your mast. Calculating your sails LP Example: If a Catalina 30 (standard rig) owner wanted a 130% headsail for his/her sailboat with a J dimension of 11.54', the LP calculation would look like this: 11.54' x 1.3 (130%) = 15.0' LP = 15'
geometry
The LP (luff-perpendicular) distance is an important dimension, since it multiplied by the length of the luff divided by 2 gives the area of the jib. Since the forestay angles back to the mast from its attachment to the deck, however, the J-dimension is going to be longer than the LP distance of any sail that clears the mast. To put this another way, a 100% genoa, using the definitions supplied by Joe and Jon W. will overlap the mast.
The LP (luff-perpendicular) distance is an important dimension, since it multiplied by the length of the luff divided by 2 gives the area of the jib. Since the forestay angles back to the mast from its attachment to the deck, however, the J-dimension is going to be longer than the LP distance of any sail that clears the mast. To put this another way, a 100% genoa, using the definitions supplied by Joe and Jon W. will overlap the mast.
Joe: Why is simple not OK?
Joe I am going to respectfully challenge your post. For those of us going out on day sails and cruising vacations - who cares? When the boat is over powered we reef the jib, then the main. Keep the boat on its feet. Who cares if you have a 150 or a 135?
Joe I am going to respectfully challenge your post. For those of us going out on day sails and cruising vacations - who cares? When the boat is over powered we reef the jib, then the main. Keep the boat on its feet. Who cares if you have a 150 or a 135?
simple is good
I'm with Higgs . Take the measurement from the forestay to the mast, thats 100%. If for example that distance is 10 feet, then if the foot (bottom edge) of the sail is 13feet long, then you have 130% or a 130. If we dont simplify, and you were on someone elses boat and you asked what size jib or jenny do you have? you would never understand their answer without the sail plan for their boat and a calculator. Leave the calculations to the sail maker.
I'm with Higgs . Take the measurement from the forestay to the mast, thats 100%. If for example that distance is 10 feet, then if the foot (bottom edge) of the sail is 13feet long, then you have 130% or a 130. If we dont simplify, and you were on someone elses boat and you asked what size jib or jenny do you have? you would never understand their answer without the sail plan for their boat and a calculator. Leave the calculations to the sail maker.
Sheesh! it's dead simple
My god the convoluted crap you can read on the net!!! Genoa percentage is figured as follows: Lay the sail flat(or if you are tall you can do this while it is hanked on). Take a simple carpenters square, lay one leg square along the luff edge near the bottom. Move the square upwards, keeping the one leg even wiht the luff. Sight along the edge of the square poining to the leech. When the inside leg points directly at the clew, mark the luff at that point. Now take a tape measure and measure the distance between the mark on the luff and the clew. THAT is the luff perpendicular(gee, a line perpendicular to the luff, who knew!) Now divide the luff-perpendicular distance by the 'J' distance multiply by 100 and you have your percentage. Example: Luff perp distance = 15' 'J' = 10' LP/J * 100=150% Now wasn't that simple and easy? Where in the world do some people come up with the garbage they write?
My god the convoluted crap you can read on the net!!! Genoa percentage is figured as follows: Lay the sail flat(or if you are tall you can do this while it is hanked on). Take a simple carpenters square, lay one leg square along the luff edge near the bottom. Move the square upwards, keeping the one leg even wiht the luff. Sight along the edge of the square poining to the leech. When the inside leg points directly at the clew, mark the luff at that point. Now take a tape measure and measure the distance between the mark on the luff and the clew. THAT is the luff perpendicular(gee, a line perpendicular to the luff, who knew!) Now divide the luff-perpendicular distance by the 'J' distance multiply by 100 and you have your percentage. Example: Luff perp distance = 15' 'J' = 10' LP/J * 100=150% Now wasn't that simple and easy? Where in the world do some people come up with the garbage they write?
Didereaux ...
...is exactly right. Realize that this means a 100% jib DOES in fact overlap the mast. higgs, in this case you are wrong. gr8_2_av8's original question was for an explanation about headsail size and how it is calculated. Just because some people are exclusively cruisers doesn't mean they don't understand how headsail size is figured. Knowledge is power, the more you know the better sailor you are.
...is exactly right. Realize that this means a 100% jib DOES in fact overlap the mast. higgs, in this case you are wrong. gr8_2_av8's original question was for an explanation about headsail size and how it is calculated. Just because some people are exclusively cruisers doesn't mean they don't understand how headsail size is figured. Knowledge is power, the more you know the better sailor you are.
and besides
the only time you use the percentage size is when you order the sail. You and your sail maker determine what inventory you need for your type of sailing. When you get your suit of sails you assign them a number. #1 being the largest genoa, 2 the intermediate genoa,sometimes called a lapper, 3 the working jib, or blade, and 4 the the storm jib. Larger racing boats often have different weights of the same size sail. It is common to have a heavy, medium and light #1 genoa. The relationship between the "J" and the "LP" depends on how high the clew is cut. A low deck sweeping racing sail would have less overlap than a high clewed cruising sail of the same percentage. Why, because the LP's location on the luff is dependent on clew's location. The higher the clew, the higher the LP's base and the closer it is to the mast, which also makes the foot longer. So ... you have different SHAPE triangles with the same SIZE (area). That's why you can't use the foot length to describe the sail's size (or percentage), higgs. The lengths of the leech and foot are related to the location of the LP base on the luff. The LP is the "height" of a triangle with the luff being its base the leech and foot the sides. So... Sailortonyb and higgs, I have no problem with keeping things simple. On my boat, and others I've crewed on, we never call the sail size to the foredeck. We call the number or sail name.
the only time you use the percentage size is when you order the sail. You and your sail maker determine what inventory you need for your type of sailing. When you get your suit of sails you assign them a number. #1 being the largest genoa, 2 the intermediate genoa,sometimes called a lapper, 3 the working jib, or blade, and 4 the the storm jib. Larger racing boats often have different weights of the same size sail. It is common to have a heavy, medium and light #1 genoa. The relationship between the "J" and the "LP" depends on how high the clew is cut. A low deck sweeping racing sail would have less overlap than a high clewed cruising sail of the same percentage. Why, because the LP's location on the luff is dependent on clew's location. The higher the clew, the higher the LP's base and the closer it is to the mast, which also makes the foot longer. So ... you have different SHAPE triangles with the same SIZE (area). That's why you can't use the foot length to describe the sail's size (or percentage), higgs. The lengths of the leech and foot are related to the location of the LP base on the luff. The LP is the "height" of a triangle with the luff being its base the leech and foot the sides. So... Sailortonyb and higgs, I have no problem with keeping things simple. On my boat, and others I've crewed on, we never call the sail size to the foredeck. We call the number or sail name.
In my defense
Alan, I will defer to your technical expertise, but disagree strongly that just because one knows the proper way to size a jib makes one a superior sailor. I have to wonder how knowing the technicalities of sail measuremnent is going to help me out on the water. When the boat is not handling right, I adjust my sails. Whether I am a "better" sailor than the next is unimportant to me. I am good enough to get my boat and its crew safely from one destination to the other without running into to anyone else. I enjoy myself and those around me.
Alan, I will defer to your technical expertise, but disagree strongly that just because one knows the proper way to size a jib makes one a superior sailor. I have to wonder how knowing the technicalities of sail measuremnent is going to help me out on the water. When the boat is not handling right, I adjust my sails. Whether I am a "better" sailor than the next is unimportant to me. I am good enough to get my boat and its crew safely from one destination to the other without running into to anyone else. I enjoy myself and those around me.
higgs
You've 'missed the boat'. My reference to knowledge is for everything you can learn, not "just because one knows the proper way to size a jib makes one a superior sailor." I'm glad that you enjoy yourself sailing, but limiting your knowledge because something might have the stigma of 'racing' attached to it, is a narrow point of view. In my book, ALL that you know and learn makes you a better sailor, regardless of whether or not you use the information.
You've 'missed the boat'. My reference to knowledge is for everything you can learn, not "just because one knows the proper way to size a jib makes one a superior sailor." I'm glad that you enjoy yourself sailing, but limiting your knowledge because something might have the stigma of 'racing' attached to it, is a narrow point of view. In my book, ALL that you know and learn makes you a better sailor, regardless of whether or not you use the information.
I don't have the racing "stigma"
Alan. I have no objection to anyone knowing this stuff - if you need it then know it. I do not need it and don't anticipate needing it. I would rather spend my time learning new anchoring techniques or something similar. My approach to this is no narrower than anyone else's. None of us can know everything there is to know about this sport so we learn what we feel we will need. The original poster said he knew nothing about it. He got some great technical answers so I thought a simple, general explanation might help him/her see the picture slightly better. I do not have a racing "stigma" and do occasionally crew for others and do some short handed races on my own boat. I think that some racers have a cruiser "stigma'.
Alan. I have no objection to anyone knowing this stuff - if you need it then know it. I do not need it and don't anticipate needing it. I would rather spend my time learning new anchoring techniques or something similar. My approach to this is no narrower than anyone else's. None of us can know everything there is to know about this sport so we learn what we feel we will need. The original poster said he knew nothing about it. He got some great technical answers so I thought a simple, general explanation might help him/her see the picture slightly better. I do not have a racing "stigma" and do occasionally crew for others and do some short handed races on my own boat. I think that some racers have a cruiser "stigma'.
How much info is too much?
The original question was posed by a new sailor. I know when i was new i wanted a relatively simple answer. I am not a racer, but i assure you i can sail from point A to point B. I am a retired engineer so i certainly can do the math. If it is a relatively light wind day I want my 150, why? because the bag says 150 not No.1. I put up the 150 which is the biggest one I own. But wait, It is not comming back that far past my mast, looks more like a 110. How do i know which one it is? I get out my square, my tape measure and a series of other stuff including a calculator, OR...I look and say to my self "self, is that a tad past the mast or is it about 50% overlapping". Maybe when you start talking 'J's, I's, LP's , etc. to a new sailor you might think to your self, is this too much information? No, probably not, because then how would i tell the sailmaker how to design a sail? Maybe a person with 'limited knowledge' in life has a need to display all his knowledge to convince the world or himself of how smart he is. maybe it is the show off that doesnt have a 'clew', LOL.
The original question was posed by a new sailor. I know when i was new i wanted a relatively simple answer. I am not a racer, but i assure you i can sail from point A to point B. I am a retired engineer so i certainly can do the math. If it is a relatively light wind day I want my 150, why? because the bag says 150 not No.1. I put up the 150 which is the biggest one I own. But wait, It is not comming back that far past my mast, looks more like a 110. How do i know which one it is? I get out my square, my tape measure and a series of other stuff including a calculator, OR...I look and say to my self "self, is that a tad past the mast or is it about 50% overlapping". Maybe when you start talking 'J's, I's, LP's , etc. to a new sailor you might think to your self, is this too much information? No, probably not, because then how would i tell the sailmaker how to design a sail? Maybe a person with 'limited knowledge' in life has a need to display all his knowledge to convince the world or himself of how smart he is. maybe it is the show off that doesnt have a 'clew', LOL.
The problem , if I may, is that
Higg's simple answer was not correct. The LP percent method of sizing a headsail has nothing to do with how far the clew overlaps the mast. It is a method for determining a sail's surface area. The higher cut the clew, the higher up the luff the LP moves, thus shortening the distance to the mast. So a high clewed sail with 100% LP will overlap the mast by a significant amount. If you have trouble identifying the sail once you take it out of the bag, then mark the size, or number, or name on the sail. A NUMBER requires less writing. And this is true for furling sails also. Mark the sail's foot or the genoa track for different settings. Finally.... this is not a racing exclusive practice. It's just a way of simplfying things to make it easier for all crew members, whether coast cruising, passagemaking, racing or daysailing.
Higg's simple answer was not correct. The LP percent method of sizing a headsail has nothing to do with how far the clew overlaps the mast. It is a method for determining a sail's surface area. The higher cut the clew, the higher up the luff the LP moves, thus shortening the distance to the mast. So a high clewed sail with 100% LP will overlap the mast by a significant amount. If you have trouble identifying the sail once you take it out of the bag, then mark the size, or number, or name on the sail. A NUMBER requires less writing. And this is true for furling sails also. Mark the sail's foot or the genoa track for different settings. Finally.... this is not a racing exclusive practice. It's just a way of simplfying things to make it easier for all crew members, whether coast cruising, passagemaking, racing or daysailing.
The reason
I guess the reason for asking the question is I want to have a jib bag made for my hank on 150% and I don't have the sail here to measure the sq footage. I guess that it may have been less contraversial to just ask if anyone knew the sq footage of a 150% for a hunter 31 84 vintage. Never the less it is very inersting and educational to get everyones perspective on the question. Keep'em coming. Dave
I guess the reason for asking the question is I want to have a jib bag made for my hank on 150% and I don't have the sail here to measure the sq footage. I guess that it may have been less contraversial to just ask if anyone knew the sq footage of a 150% for a hunter 31 84 vintage. Never the less it is very inersting and educational to get everyones perspective on the question. Keep'em coming. Dave
Genoa
See higgs first post, slightly modified: -on a 100% jib the foot will go back as far as the mast. -on a 150% genoa the foot goes 50% past the mast. That's it stated in a simply form.
See higgs first post, slightly modified: -on a 100% jib the foot will go back as far as the mast. -on a 150% genoa the foot goes 50% past the mast. That's it stated in a simply form.
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