Used sail fit analyser
Screen geometry and interfaces together. A good score means the candidate deserves detailed inspection—not that the sail is proven to fit or is safe to use.
Turn assumptions into written checks
Measurements and scores organise the buying conversation. Keep photos, record uncertainty and ask the provider to confirm final dimensions, engineering, hardware, material, price, delivery and commissioning in writing.
How close do used sail dimensions need to be?
There is no universal tolerance. Edge lengths are only a first screen; rig clearance, LP, clew position, hardware and condition can reject an apparently close sail.
Can a furling sail fit the wrong furling direction?
The UV cover normally needs to face outward when furled. Its side, the drum direction and the luff system must be confirmed before purchase.
Does a high fit score prove the sail is safe?
No. The score only organises the supplied facts. A qualified sailmaker must inspect the cloth, stitching, structure and actual fit.