A headsail has to fit the foretriangle and your sheet leads and your furler. These are the coded values on our headsail form (CS-HS-02), in centimetres.
Before you put a tape on anything
Attach a non-stretch surveyor's tape and retrieval line to the halyard shackle or upper swivel, raise it to the full hoist, and record Lp, I and B before lowering. For the track-end spans — B, SA and SY — route the tape around the shrouds and pull it taut. That's not fussiness: the sail has to get round them too, and a straight-line measurement describes a path your sail can't take.
The coded measurements
| Code | What it is, and where the tape goes | Where |
|---|---|---|
| LpLuff | Full-hoist bearing down to the tack fitting, or to the furler tack pin. | |
| IForetriangle height | Hoist point to the side deck at the mast. | |
| JForetriangle base | Forestay pin to the mast foot. | |
| BHoist to forward track end | Hoist point to the forward end of the track — tape routed around the shrouds. | |
| SAForestay to aft track end | Forestay pin to the aft track end — around the shrouds. | |
| SYForestay to forward track end | Forestay pin to the forward track end — around the shrouds. | |
| RForestay to furler tack | Forestay pin to the tack pin on the furler. Hank-on boats leave this blank. | |
| KFurler tack to gate | Tack pin on the furler to the foil entry gate. Hank-on boats leave this blank too. | |
| Lw / LdOld sail leech & foot | If you're sending your old sail's numbers, they go here — and the form labels them reference only. See measuring a sail you already own for why. |
Which side is your UV strip on?
Our form has a field for it: UV on port, or UV on starboard. A furling headsail is cut to roll one specific way, and the UV strip goes on whichever face ends up outside. Get the side wrong and the strip rolls up inside the sail — you paid for UV protection and the sun eats the sailcloth anyway. It is the single most common expensive mistake on a second-hand furling genoa, and it is invisible in every measurement on this page. The form also asks your furler type and article number, whether your leads are on a sheet track or fixed points, whether the track is on the roof or the deck, and whether your spreaders are swept or in-line — because those decide whether the sail can be sheeted at all. Fixed leads: leave B, SA and SY blank and send us the fixed-point geometry.
The rule that runs through every form we print
If you aren’t sure of a bearing, leave it blank and tell us. Our forms say it on every page, and it isn’t politeness — it’s arithmetic. A blank is a question we can answer with one phone call. A guess is indistinguishable from a measurement, so it survives all the way to the cutting floor and comes back as a sail that doesn’t fit. We would rather have four honest numbers and a note than five numbers where one is fiction.
The words on this page, explained
Or don’t measure anything at all
The easiest measurement is the sail you already own. Bag it, send it, and we’ll do all of this on a flat loft floor with proper tension — then send you the production dimensions to approve before we cut.