What diameter should you choose for your halyards?
Table of contents
To refit a second-hand sailboat and give it a new lease of life, or simply due to wear and tear on your boat's ropes, you may need to change the lines.
Once you know which halyard to choose, that is, the type of rope (polyester, high-modulus polyurethane, static polyamide, Dyneema/polyester mix, etc.), you still need to determine the correct diameter.
Diameter based on hardware
The first thing to check is your boat's hardware.
Generally, your clutches, winches, or cleats will determine the minimum and maximum diameter of the ropes.
If the diameter is too small, your rope won't hold in the clutches; it will slip.
If the diameter is too large, it simply won't fit.
To keep things simple and practical, a good method is to simply buy new halyards of the same diameter as the previous ones.
No risk, you're sure it will hold.
Breaking strength
This is an essential criterion: your halyards must have a breaking strength adapted to the load they will have to bear, i.e., the weight of your sails.
Whatever the rope, the larger its diameter, the higher its breaking strength.
How to calculate the halyard diameter?
In fact, the real question is how to calculate the load to be supported. There are 2 simple calculation methods.
Quick method
We will simply multiply the sail area in m2 by a coefficient.
Spinnaker = area x 30
Mainsail = area x 100
Genoa = area x 80
More precise method
Sail area (m²) x Wind speed² (in knots) x 0.021 = Working load (in daN) x 5 = Breaking load
Once the breaking load is calculated, it is necessary to check which diameter of the chosen halyard offers sufficient breaking strength.
Consider the weight
The diameter of a rope will have a direct impact on its weight, which is detailed in the technical table at the bottom of each product page on the website.
For some halyards, especially for cruising, weight is not such an important factor: this is the case for the mainsail halyard or the genoa halyard.
However, a spinnaker halyard that is too heavy will slow down the sail's inflation and hinder your navigation. Even without seeking performance, sailing should remain a pleasure to fully enjoy the sea.
Oversizing your halyards?
Can oversizing your halyards be beneficial for your sailing or equipment?
Yes!
An approach that is seemingly contradictory to the point just above, because increasing the diameter means more weight.
But oversizing a halyard will allow it to work, for example, at only 25% of its breaking strength, thus reducing its elongation and improving its performance.
Depending on the halyard (Spinnaker, Mainsail, Genoa), it is therefore also a calculation to be made and a compromise to be found.
