The biggest decision on a headsail, and the one that decides how the sail sails in three years rather than in its first season.
The three families
| Dacron | Woven polyester. Durable, tolerant of rough handling, repairable anywhere, stretches more as it ages |
| Laminate | Film and load-bearing fibres between woven faces. Holds its shape far better, weighs less, wants looking after |
| SurgeX | Continuous fibre laid along the load paths of your particular sail. Best shape retention, lightest for its strength |
How each is actually made is in Upwind & Code Zero Sailcloth. The available families, mills and weights are listed in Sailcloth.
Why it matters more here than on a mainsail
As a woven cloth ages it stretches, and the sail gets deeper through the middle with its deepest point further aft. The familiar word for it is a belly.
That is what costs pointing. A deep sail with its draft aft heels the boat instead of driving it, and will not sail as close to the wind. An old genoa is noticeably worse to windward long before it looks worn out. A mainsail that has gone slightly full is a nuisance; a headsail that has gone full stops the boat pointing.
Choosing
Dacron for a cruising headsail that will be handled hard, rolled wet, and expected to last. This is right for most boats, and a well-chosen Dacron genoa is not a compromise.
Laminate where you sail enough that the entry going soft would annoy you, and the sail will be looked after.
SurgeX where shape retention and weight are the point.
One thing to avoid: a low-stretch cloth and a very large overlap. A big genoa is dragged past the shrouds twice an hour and a light cloth will not survive it. Overlap and cloth are one decision, not two.
Weight
Heavier is not safer. Too light for the sail and it stretches early; too heavy and the sail is hard to roll, slow to fill in light air, and no longer-lived for it.
For Dacron the weight is read off the cloth manufacturer’s published tables for your sail’s size rather than estimated, so it is not something you have to judge.
What follows from the cloth, without being asked
How the sail is cut. Woven cloth is strongest in one direction, so the panel layout has to match it — Cross-Cut and Radial-Cut.
How much protection it needs. Laminates and continuous-fibre structures are more UV-sensitive than woven polyester, which raises the stakes on the UV cover.
How to stow it. Rolling suits every cloth, and a laminate particularly — a roll is a gentle curve, not a crease. What a laminate objects to is folding, and folding on the same lines year after year most of all. A furling headsail is stowed correctly by default; the thing to avoid is folding it small for the winter along the same creases.
Construction follows the cloth
A woven cloth is strongest in one direction, so its panel layout has to put that direction where the loads run. Cross-cut and radial constructions are offered only where they suit the selected cloth and sail; the two are not mixed within one sail. Cross-Cut and Radial-Cut explains why.
For SurgeX the question does not arise in the same form, because continuous fibres carry the primary loads. Fibre density and the load paths around the corners and any batten positions are engineered for the individual sail rather than selected as fields.
The cloth also sets the starting point for corner transitions, edge tapes, stitching, UV protection and the foam-luff structure. Lower stretch does not mean less reinforcement: it means concentrated loads have to be distributed into the sail more carefully.
Thread, stitch rows, tape widths, fibre density and plot layout are production specifications confirmed during Sailmaker Review.
Configuring this at SurgeSails
Range selects the family and Cloth the specific weight or grade. Choosing SurgeX adds Fiber Material and DuraSkin with its colour. Cut construction is selected automatically from the chosen cloth: radial-compatible laminate uses tri-radial panels, while woven and other non-radial cloth uses cross-cut. For a radial sail, panel density is also calculated automatically from foot length (approximately one panel per 600 mm), so the editor does not expose a manual cut-style or radial-division selector. Older saved seam-mode values may still be read for migration, but they do not override the current automatic preview or build specification.