A furling main lives or dies on its luff rope and its entry gate. These are the coded values on our furling-mainsail form (CS-FM-01). Everything is in centimetres — including the luff rope, which is why you will see it written as 0.8 rather than 8.
Before you put a tape on anything
Attach a non-stretch tape and retrieval line to the main-halyard shackle or head fitting, hoist to the maximum, and record Lp/P and Lw before lowering. Identify every lower bearing before you start measuring — deciding what counts as “the tack” after the tape is up is how the numbers go wrong.
The coded measurements
| Code | What it is, and where the tape goes | Where |
|---|---|---|
| Lp / PLuff | Maximum main-halyard hoist down to the tack fitting. | |
| LwLeech | Maximum main-halyard hoist to the clew connection. | |
| Ld / EFoot | Tack fitting to the clew connection, or to the boom black band. | |
| ATack to furler entry | Tack bearing to the furler entry. Leave it blank if your hardware differs from the diagram on page 1 — don't force it. | |
| BBackstay clearance | Aft mast face to the backstay, horizontal at boom level. | |
| CLuff-rope diameter | The rope in your luff, in centimetres. An 8 mm rope is entered as 0.8. Get this wrong and the sail will not feed into the foil. |
What we deliberately leave blank
Code D — mast-crane clearance — stays empty on your form. Not an oversight: we won't fill it until we've verified a model-specific datum from your mast reference and a square-ruler photo. The form asks for the mast reference, the furler reference, the sail number and the clew UV protection colour instead. A blank we can see is safer than a number we guessed.
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.