Jib

Definition and key measurements

The jib fills the foretriangle forward of the mast without crossing the mast centerline.

Standard dimensions:

I = forestay height (deck to hounds)

J = foretriangle base (mast to stem)

LP = perpendicular distance from luff to clew (≤ 100 %)

Area = (I × J × LP%) ÷ 2

Luff type: wire, rope or foil

Jib categories

Working jib

LP 90–100 %

Versatile all-round sail for 10–20 kn

Cross-cut Dacron 6.5–8 oz

Hanks or furling foil

Moderate draft for balanced helm

Blade jib

LP 70–90 %

Flat cut for 20–30 kn and choppy water

Tri-radial laminate or 8–9 oz Dacron

Reduces heel and weather helm on fin-keel boats

Standard on performance cruisers 35–45 ft

Heavy-weather jib

LP 85–95 %

Built for 25–35 kn; replaces partially furled genoa

9–10 oz Dacron or hydranet radial

Foam luff pad for shape when reefed

Hanked on inner forestay or roller-reefed

Storm jib

LP < 40 %; high-visibility orange

9–11 oz Dacron, triple-stitched

Hanked on removable inner stay; never furled

Required for World Sailing OSR Category 0/1

Area ≈ 5–7 % of rated mainsail

Selection criteria

1. Measure I and J from rig plan or tape.
2. Match LP to wind range:
   • Coastal cruising → 95 % working jib
   • Offshore passage → 85 % blade + storm jib
   • Club racing → 70 % blade + #3
3. Crew preference: hanks for reliability, furling for convenience.
4. Cloth weight: increase 1 oz per 10 ft LOA above 30 ft.

Maintenance protocol

• Rinse with fresh water after every sail.
• Flake zigzag; avoid hard creases on battens.
• UV strip facing sun when furled.
• Inspect hanks, telltales and seam chafe monthly.
• Replace UV strip every 4 years.

End-of-life upcycling

When stretch exceeds 15 % or UV damage penetrates the resin, retire the jib. Resail harvests panels for:

• 25 L day-sail backpacks with original hanks
• Padded winch handle sleeves
• Waterproof chart cases (8,000 mm HH)
• Reversible cockpit cushions

Procurement and upcycling

Send I and J measurements to info@resail.org for a matched second-hand jib or to schedule free collection of your retired sail. Every exchange keeps 8 m² of performance cloth in circulation.