The diameter of these lines is determined by the type of use and the size of the boat.

However, it is essential to ensure compatibility with clutches, blocks, and winches to avoid any unpleasant surprises.

Choosing the right diameter for a halyard or sheet can help optimize weight in the mast, reduce friction, and improve overall performance.

Select the rope material, terminations, and any additional fittings according to your specific needs.

Here is the recommended diameter chart for each type of line based on your boat size.

To determine the ideal length of a line (halyard, sheet, control line, etc.), it's important to consider both its function and the complete path it takes on board.

Method 1: Measure

Carefully measure the actual route the line takes, following it through all relevant fittings: blocks, sheaves, clutches, cleats, and turning points.
We recommend adding a 10–15% safety margin to this measurement. This extra length accounts for knots, adjustments, and the natural stretch of the line. When in doubt, it's always safer to go a bit longer: a line that's too short is unusable, while excess length can always be trimmed or adjusted.

Method 2: Calculate

You can also estimate line lengths using formulas based on the standard rigging dimensions of your boat: I, J, P, E, which refer to:

• I – Height of the forestay attachment point from the deck

• J – Distance between the front of the mast and the forestay fitting at the bow

• P – Maximum usable luff length for the mainsail

• E – Maximum usable foot length for the mainsail

Here are a few useful formulas to help you cut your lines to the correct lengths:

Practical formulas to help you cut your lines to the right lengths:

• Furling genoa sheet= LOA × 1.1

• Asymmetric spinnaker sheet = LOA × 2.2

• Genoa control line = LOA × 1.5

• Main halyard / topping lift= (√(P² + E²) + P + P×0.1 + E) / 100

• Spinnaker halyard (head)= (√((P×1.1)² + J²) + P×1.1 + J) / 100

• Genoa halyard = (√(I² + J²) + I + E) / 100

LOA = Length Overall (total boat length)