My running rig looks quite old, so I decided to change it. The answer to the question what kind of lines I need appeared not to be very straight forward. I searched in Internet and different forums, but people suggested lines basically based on the lines diameter, but not the line strength. I think it is clear to everyone that a line with smaller diameter in some cases could be tougher than a line with larger diameter. Finally I found some formula by which one could calculate the approximate load on a Genoa and Main sheet, which numbers could be a good starting point when you decide about the lines:
1. Genoa.
So, about the Genoa it looks pretty straight forward:
SL = SA x V² x 0.02104
Where: SL = Sheet Load in kilogramsSA = Sail Area in square metersV = wind speed in knots
Where: SL = Sheet Load in kilogramsSA = Sail Area in square metersV = wind speed in knots
For Genoa number 1 (about 18 square meters), and a wind speed of let say 40 knots, the sheet load in kilograms will be about 600 kilograms force or 600 daN.
For storm sail (about 5 square meters), and a wind speed of let say 100 knots, the sheet load in kilograms will be about 1052 kilograms force or 1052 daN.
I decided to get for a Genoa sheet line of 12 mm with strength of 3014 daN (Hurricane polyester double braided Lanex sheet).
I think that it is unlikely that the Genoa sheet of Contessa could suffer more than 1052 daN, if it happens the Genoa sheet will be the smallest problem which you will have to deal with.
For the Genoa halyard I decided to go for 3600 daN Dynema 8 mm line.
2. Main sail.
Estimate of the main sheet load could be made by the following formula:
ML = E² x P² x 0.02104 x V² / (sqrt (P² + E²) x (E - X))
Where:
ML = Mainsheet Load in kilograms
E = Foot length on main in meters
P = Luff length of main in Meters
V = Wind speed in knots
X = Distance from aft end of boom to mainsheet attachment point.
ML = Mainsheet Load in kilograms
E = Foot length on main in meters
P = Luff length of main in Meters
V = Wind speed in knots
X = Distance from aft end of boom to mainsheet attachment point.
For Main sail (about 12 square meters), and a wind speed of let say 60 knots, and X = 0.5 m the sheet load in kilograms will be about 685 kilograms force or 685 daN.
I decided to go for the same lines as for the Genoa, Main sheet line of 12 mm with strength of 3014 daN (Hurricane polyester double braided Lanex sheet), and Main halyard of 3600 daN Dynema 8 mm line.
My traveler blocks are 4:1 system, which I expect to reduce the force on the main sheet by factor of 3, and I decided to go for blocks with working load of 700 daN.
For the boom vang, I decided to go for 500 daN blocks 4:1 system and 10 mm lines 2500 daN.
More information about the sheet load one can find here:
