Have a C 30 std rig. The brochure specs say it has a certain sail area with a 100% foretriangle. Mine I believe has a 150% genoa per the factory order sheet from 1984. Dumb question, anyone know what my sail area would be? Bob Lufkin C 30 Windborne 1984 3634
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E
Edward Steenstra, III
M
Mike Kenny
HS math...
Area = (base * height / 2) works when the height is the perpendicular distance between a vertex and the opposite side. So, you would need to know a perpendicular measurement like clew to luff (clu) and length of the luff (lu), then: Area = (clu * lu / 2) or the perpendicular measurement from the tack to the leech (tle) and the length of the leech (le): Area = (tle * le / 2). Otherwise you can calculate the area of any triangular sail with: le = length of leech lu = length of luff fo = length of foot s = (le + lu + fo) / 2 Area = Square Root (s * (s -le) * (s - lu) * (s - fo))
Area = (base * height / 2) works when the height is the perpendicular distance between a vertex and the opposite side. So, you would need to know a perpendicular measurement like clew to luff (clu) and length of the luff (lu), then: Area = (clu * lu / 2) or the perpendicular measurement from the tack to the leech (tle) and the length of the leech (le): Area = (tle * le / 2). Otherwise you can calculate the area of any triangular sail with: le = length of leech lu = length of luff fo = length of foot s = (le + lu + fo) / 2 Area = Square Root (s * (s -le) * (s - lu) * (s - fo))
B
Bob
You need to know
the percentage of overall sail area the jib represents. For example, if the main is 200 sq.ft. and a 100% jib is 200 sq.ft. your total sail area is 400 sq.ft. (duh). So if that jib were replaced by a 150, the new headsail would have an area 1.5 times the old one, in this case 300 sq.ft., giving you 500 total. Your Catalina 30 looks to have main and #1 jib of about equal areas, and looking at some old specs I see the total sail area listed at 444, so if the #1 jib is about 222, the 150 genoa should be about 333 sq.ft., yielding a total area of 555 sq.ft. with the big headsail. This is ballpark, but I bet it's not too far off.
the percentage of overall sail area the jib represents. For example, if the main is 200 sq.ft. and a 100% jib is 200 sq.ft. your total sail area is 400 sq.ft. (duh). So if that jib were replaced by a 150, the new headsail would have an area 1.5 times the old one, in this case 300 sq.ft., giving you 500 total. Your Catalina 30 looks to have main and #1 jib of about equal areas, and looking at some old specs I see the total sail area listed at 444, so if the #1 jib is about 222, the 150 genoa should be about 333 sq.ft., yielding a total area of 555 sq.ft. with the big headsail. This is ballpark, but I bet it's not too far off.
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Joe
sail area
To figure sail area you need to know the following dimensions. (L) LUFF - length of the sail's leading edge) (LP)LUFF PERPENDICULAR - a line perpendicular to the luff that bisects the clew (sail's rear corner) (In Geometry the Luff would be called the Base and the LP would be called the Height. A=1/2BH) Therefore: Sail area = L x LP divided by 2 Now... let's add another dimension called the "J". This is the distance between the headsail tack fitting and the front of the mast. Headsail SIZE is expressed as a percentage. It is the relationship between the sail's "LP" and the foredeck dimension "J" Therefore: Sail size = LP / J. If the "J" equals the "LP" then you have a 100% jib. Sails 100% or less are called "Jibs", larger than 100% "Genoas". By the way, on your boat (according to the Catalina Yachts website) the "J" is 11.5 Ft. The Link below will take you to North Sails' CruisingDirect website that gives you exact instructions on how to measure all your sails. ('cause they want you to buy some) Anyway it's very interesting. Have Fun.
To figure sail area you need to know the following dimensions. (L) LUFF - length of the sail's leading edge) (LP)LUFF PERPENDICULAR - a line perpendicular to the luff that bisects the clew (sail's rear corner) (In Geometry the Luff would be called the Base and the LP would be called the Height. A=1/2BH) Therefore: Sail area = L x LP divided by 2 Now... let's add another dimension called the "J". This is the distance between the headsail tack fitting and the front of the mast. Headsail SIZE is expressed as a percentage. It is the relationship between the sail's "LP" and the foredeck dimension "J" Therefore: Sail size = LP / J. If the "J" equals the "LP" then you have a 100% jib. Sails 100% or less are called "Jibs", larger than 100% "Genoas". By the way, on your boat (according to the Catalina Yachts website) the "J" is 11.5 Ft. The Link below will take you to North Sails' CruisingDirect website that gives you exact instructions on how to measure all your sails. ('cause they want you to buy some) Anyway it's very interesting. Have Fun.
A
Al
lufkin?
gee Bob , with a name like "lufkin" i would think a question about measurement would be a "no brainer"
gee Bob , with a name like "lufkin" i would think a question about measurement would be a "no brainer"
B
Bob Lufkin
ha ha ha Al
I guess I was really trying to figure out what the % mean in regard to headsails. Like 100%, 135%, 150% of what? The main or orginial jib?
I guess I was really trying to figure out what the % mean in regard to headsails. Like 100%, 135%, 150% of what? The main or orginial jib?
J
Joe Ford
Size matters....
See my previous post for an explanation of "J" and "LP" Since the boat's "J" dimension is constant, the sail's size is expressed as a percentage relationship the boat's "J" and the sail's "LP." If your "J" dimension is 11.5 ft. then the "LP" of a 150% genoa would be 17.25 ft. ... 11.5 X 1.5= 17.25 A headsail with an "LP" of 10.35 ft would be a 90% jib. ...11.5/10.35=.9 So what would a 135% genoa's LP be on the same boat? If the sail's luff is 36 feet long can you figure its area? Remember: Headsail SIZE is NOT the same term as headsail AREA. See, they were right, you will use this math stuff in your life after high school.
See my previous post for an explanation of "J" and "LP" Since the boat's "J" dimension is constant, the sail's size is expressed as a percentage relationship the boat's "J" and the sail's "LP." If your "J" dimension is 11.5 ft. then the "LP" of a 150% genoa would be 17.25 ft. ... 11.5 X 1.5= 17.25 A headsail with an "LP" of 10.35 ft would be a 90% jib. ...11.5/10.35=.9 So what would a 135% genoa's LP be on the same boat? If the sail's luff is 36 feet long can you figure its area? Remember: Headsail SIZE is NOT the same term as headsail AREA. See, they were right, you will use this math stuff in your life after high school.
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