Above: this sequence
shows how the Helix Luff Cord delivers a safe, reliable tight furl all the way from head to foot, ruling out the risk of the sail unfurling prematurely. The TP52 Beau Geste was one of three programmes that tested the Helix Luff Cord and provided valuable feedback during the development. The Helix Luff Cord (near left) delivers reliable top- down furling at a fraction of the size, weight, and stiffness of traditional anti-torsion cables (far left)
Why reliability of top-down furling is important Bottom-up furling engages the bottom of the sail and is less efficient with the sail’s upper section. Larger and wider-girth sails (greater than 55-60 per cent mid- girth) benefit from top-down furling. Bottom-up furling can work on 75 per cent mid-girth Code Zeros with small luff lengths, provided the crew pay attention to the furl.
Helix Luff Cords explained Helix Luff Cords are developed specifically to work with North Helix 75-65 per cent girth sails. The cord is designed to set with two per cent sag and a load share between 20 per cent and 50 per cent of the total tack load. There are two styles of the Helix Luff Cord - Blue Water and Grand Prix. The primary difference between these cords is their intended application.
Blue Water Cord: to be used as an all-purpose cord, designed for inshore and offshore use where the
When a sail furls in the bottom and does not carry enough furling revolutions with one or two turns, the top of the sail is susceptible to unfurling prematurely. If this happens and then the bottom of the sail is unfurled, you get a twist in the luff where the top furls one way and the bottom the other. This is costly during active racing and results in loss of boatspeed, and thus boat lengths.
sails loading could be higher, and potentially used in higher wind speeds or offshore conditions. For the Blue Water Cords a load sharing of 50 per cent is used as the cord’s EA design point; the cord still intended to sail with an 80/20 sail/cord load ratio.
Grand Prix Cord: with a design point load share of 20 per cent, it is intended to be used as a day race cord sail with the crew having tight control on sail loading. It’s generally only applicable on North 3Di Downwind Helix sails.
SEAHORSE 69
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