Straight Luff Furlers

Straight Luff Furling is a versatile solution, perfect for various sail types such as Code Zeros, Reachers, and Gennakers. These sails have more shape than a genoa, but not so much that they can't be furled around a luff rope. They require an anti-torsion line sewn into a pocket on the sail's luff.

With Straight Luff Furling, the process is a breeze. As furling begins, the tack and head of the sail rotate in sync, neatly bringing the sail in. Once furled, the sail and the torsion rope can be effortlessly stowed and replaced, making for quick and easy sail changes.

Straight Luff Furlers, also known as Bottom-up Furlers, are Continuous Line Furling Systems developed to make reaching sails, e.g. Code Zero, much easier to handle. Although relatively deep and lightweight compared with a genoa, a certain degree of luff tension is still required to enable pointing, hence the term straight luff furler.

The torsional cable is enclosed in a pocket that runs up the sail's luff.

The Tack is lashed to the bottom thimble eye in the torsional cable.

The Head is also lashed to the thimble eye of the torsional cable at the head.

The sail is stowed with the cable threaded through the luff pocket and firmly furled.

Straight Luff Furler Deployment:

Attach the bottom thimble eye to the fork on the top of the drum and fix the top thimble eye to the fork on the swivel at the head

Hoist the complete system as a tightly furled unit and tighten the luff by hauling on the halyard to achieve the required tension

Spin the wheel to unfurl by pulling on the appropriate part of the continuous furling line

Spinning the wheel in the opposite direction by pulling on the other part of the continuous furling line results in the bottom of the sail wrapping around the torsional cable first, and then the roll gradually rises up the luff – Hence the term bottom up

Bottom-up Furling Basic Facts:

• Suitable for straight luff, reaching sails
• Torsional cable runs through a luff pocket sewn into the sail
• Head and Tack are attached to either end of the torsional cable
• Furling begins at the tack and works its way up the luff to the head

Straight Luff Furling (Bottom Up) Cables - Key Performance Factors

• High Working Load Capability to achieve the required luff tension
• Cable stiffness
• Minimum diameter to reduce upwind drag
• Effective initial Anti-Torsional performance – after a few turns, the increased diameter of the rolled sail will help to transfer the torque up the cable and add to the effective torsion of the system with each successive roll

PBO is the stiffest, lightest and smallest diameter soft composite fibre available on the market and is generally regarded as the optimum core material for bottom-up furling cables

Zylon® PBO: Facts, Features and Plus Factors

• Developed in the 1980s
• The world’s strongest synthetic fibre
• The first organic fibre with cross-sectional strength superior to both steel and carbon fibre
• Excellent strength and modulus
• Good flame resistance
• Excellent thermal stability
• Excellent creep resistance
• Good chemical resistance
• Composition: rigid-rod isotropic crystal polymer, spun by a dry-jet wet spinningEffective process

The Jimmy Green Rigging Team can help you choose a system from top manufacturers Profurl, Karver, Selden, and Harken.