Please select your home edition
Edition
YY.com app (top)

Torsional Furling Cable - What's an S-Splice?

by Kerri Robson 22 Feb 09:00 UTC
S-Splice termination in torsional rope © Kohlhoff Rigging

When it comes to furling cables, custom top-down cables (for loose luff, asymmetrical gennakers) and bottom-up cables (for code zeros and staysails) can sometimes be expensive. For small to medium sized racing and cruising sailboats (up to 45ft), torsional rope can often be a viable and cost-effective alternative for performance furling systems.

Thick, dense and resistant, torsional rope is a high-performance composite cable which is specifically designed to provide maximum torsional stiffness, whilst remaining flexible enough to be stuffed into a sailbag after use. As a result, torsional rope is great for high speed furling, ensuring fast torque transmission along the cable from the tack to the head of the sail.

At upffront we distinguish between:

Torsional Cables - which are made to a specific length, in the factory, by winding high performance single, fibre tows (commonly K49, SK99 or PBO) around two end thimbles

Torsional Ropes - which are supplied by the manufacturer, in long lengths on a reel, and can be finished to the correct length on site, yourself or by a rigger / sailmaker

To produce a finished torsional rope, the cable is cut from a roll and needs to be terminated, at the required custom length, around a thimble at each end (to fit your furling unit/swivel). Due to the nature of the rope, it is impossible to splice and the ends of rope are commonly secured with a metal clamp.

However, using a metal clamp as the termination method has disadvantages. Heavy and bulky, it is possible the cumbersome clamp could catch your sail or possibly even tear it in addition to being a real snag hazard for sheets and lines. What's more, in our view the use of metal clamps, on a high-performance composite material, is archaic and doesn't align with upffront.com's continued passion for lighter, faster, and safer sailing.

One of our preferred suppliers, Kohlhoff Rigging, are making waves in torsional rope innovation, inventing a truly unique, modern, soft solution that has been well received and endorsed by industry professionals across Germany and Northern Europe.

Instead of a clamp, their progressive 'S-Splice' termination makes use of the simple, but highly effective, 'Chinese finger trap' principle.

Similar to the premise behind the Cousin Trestec Constrictor, the braided textile sock constricts, utilising friction, to keep the ends of the torsional rope in place around the thimbles. In addition to the textile sock, the cable's Polyester and Dyneema covers are also glued with a special PU adhesive, ensuring maximum stability and durability.

Further, the ends of the torsional rope, bound by the textile sock, are tapered thus creating a streamlined transition with no hard edges (unlike a cable with a metal clamp). Consequently, the cable is less likely to get caught on sailcloth, lines or sheets - plus the tapered edge can easily go inside the sail luff pocket.

Benefits of this 'braided sock' termination method, in comparison to a metal clamps, include: lower profile, lightweight, flexible and soft thus meaning it is kinder on the sails.

On top of all this, the standard thimble used by Kohlhoff Rigging is a Loop Product, purpose-built for this technique. This thimble has an additional hole which the braided cover travels through, meaning it is impossible for the thimble to twist out of the eye in the torsional rope, which can be an issue with other methods.

The Kohlhoff Rigging S-Splice has been fully load-tested and exhibits excellent grip (due to the braiding angle of the cable jacket which is optimised for grip and anti-twist), good breaking strength and the special aramid cover prevents slipping of the splice and ensures optimum torque transmission.

Thinking of trying torsional rope out? Get in touch with any queries via the upffront.com 'Furling Enquiry Form' or shop torsional ropes here.

Related Articles

Reducing Weight Aloft with Composite Backstays
Simple replacement offerring superior performance over wire Reducing weight aloft is one of the most cost effective ways of increasing your boat speed and performance: every kilogram you take out of the rig is roughly equivalent to 4kg added to the bottom of your keel. Posted on 22 Apr
PROtect Tapes take on regatta plastic pollution
Biodegradable and compostable hull stickers available Experts at creating products designed to tackle chafing, abrasion, scratches, damages, ageing, and wear, PROtect Tapes have now honed their unique technical film know-how to create biodegradable and compostable bow and hull stickers Posted on 17 Apr
Fresh In - Tiller Extensions
From three big players: Spinlock, Harken and Ronstan We are excited to now introduce six ranges of tiller extensions on upffront.com, from three big players: Spinlock, Harken and Ronstan. Posted on 15 Apr
Dyneema Braided Cover
The latest addition to your tool kit Dyneema® is the strongest fibre in the world. Ten times stronger than steel, and seven to ten times lighter than a steel wire of equivalent size, Dyneema® is one of the most durable and sought-after materials on the sailing market. Posted on 8 Apr
Robline Rope: Dinghy Ranges
Extensive range specifically developed for dinghies and small sport boats Robline has an extensive range of lines specifically developed for dinghies and small sport boats. In this post, we discuss the different types of dinghy lines and their recommended applications. Posted on 3 Apr
Bjarne Lorenzen talks Top-Down Furling
Andy Rice interviews Bjarne Lorenzen of sailmaker Doyle O'leu In part three of this series, Bjarne Lorenzen of sailmaker Doyle O'leu explains the benefits of top-down furling, one of the big developments of the past decade which has trickled down to the cruising scene from the Volvo Ocean Race. Posted on 29 Mar
Lash Thimbles
What are they, and how do I use them? Lash thimble, ferrule, rope thimble, bobbin or low friction ring... whatever you call them, there's no denying they are the perfect (low cost!) solution for a multitude of applications. Posted on 25 Mar
How do I rig the bobstay of my Trogear bowsprit?
Reaping the benefits of a retrofitted removable bowsprit The bobstay is connected to the tip of the bowsprit and routed to a u-bolt, which is attached on the bow. Assuming the sails are deployed and the bowsprit is horizontal, the bobstay should achieve an angle of 45 degrees or more. Posted on 20 Mar
Ronstan Core Block Range
Significant time and effort invested in developing this range Ronstan invested significant time and effort in developing this functional and stylish range, for keelboat sailors. Posted on 15 Mar
Introducing the LOOP Products E-Furler
Gennaker furling at the touch of a button Launched at Dusseldorf Boatshow 2017, the LOOP® Products E-Furler 1500 brings push-button technology, safety and comfort to sportsboat gennaker furling. Posted on 11 Mar
YY.com app (top)