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Lengths of Sheets and Halyards

We are constantly reporting on the latest innovations in the marine industry which offer weight savings whilst, at the same time, increasing safety factors. The result: lighter, faster, safer and more exciting sailing.

Lengths for sheets and halyards

We have previously discussed taking care of ropes, but, how long should these ropes even be? As previously mentioned, ropes are an essential element of your rigging system, and optimising your running rigging lengths is important.

Why is it imperative to have the correct lengths for sheets and halyards?

Obviously, too short a sheet or halyard does not get you anywhere. A rope that is too long increases the chances of getting tangled, adds to the overall weight of the boat and it’s just a waste of money!

Length Calculations and Formulas

You have chafed through a sheet / halyard, on your holiday, and need an emergency replacement shipped to you. How long should your new line be?

Standard sail-maker I.J.P.E. dimensions are usually the most commonly available data to work from. The following diagrams and formulas will then help calculate the most appropriate length for your ropes.


Don’t worry, this isn’t complicated maths, or rocket science.  However, please do bear in mind that these are measured in metres, thus all rope lengths (results) are defined as such.

upffront diagram 2


P: Mainsail hoist length

E: Mainsail foot length

I: Height of the forestay above deck

J: Length from mast to forestay

Y: Distance from halyard winch to mast

X: Distance from genoa winch to mast

Z: Height of boom above deck

L: Boat length





north sails diagram



         Ig: Height of Inner Forestay above deck

         Py: Mizzen hoist length

         Ey: Mizzen foot length





                                                            Source of Diagram: North Sails













IJPE Formula applied to Beneteau First 40 (Source of boat data: Sailboatdata.com)

L= 12.24m 

I= 16.05m benetau40

P= 15.57m

J= 4.60m

E= 5.39m

Main Halyard 1:1 (Winch on mast) = 2.1×P+2

Therefore = 2.1x15.57 +2
Main Halyard Rope Length= 34.70m


Gennaker Sheet= 2.5xL                                                     Image Source: Sailboatdata.com

Therefore = 2.5x12.24
Gennaker Sheet Rope Length= 30.6m

Safety Margin

Most of these formulae add an extra one or two metres, which translates to a little more ‘extra rope’ as a ‘safety margin’.



Rigging systems must have accurately measured and cut ropes to function properly. This then enables sheets to control and halyards to hoist sails efficiently. A general rule of thumb to calculating the length of halyards is to use the ‘vertical’ P / I measurements (height of the mast), while calculating the length of sheets then uses the ‘horizontal’ E / J, plus overall boat length.


                                                   Free running rigging guide


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