Sail

Use telltales on both sides of the sail; ideally, they should be parallel and flowing backward to confirm laminar flow. Preparing For The Storm : How to Lie A-hull

Achieving a "deep" sail shape is about maximizing the lift-to-drag ratio and harnessing kinetic energy from the wind. Use telltales on both sides of the sail;

Aim for a maximum draft position about 40–50% aft on the sail to allow for gradual, efficient curvature. Use telltales on both sides of the sail;

A slightly "hooked" or curved leech can add lift but may cause the boat to struggle if over-tightened. Use telltales on both sides of the sail;