Calling for a code zero!

Practical: Sails

David McKay decides to enlist the big guns to speed things up in light winds.

Our yacht, Diomedea, needed more horsepower in light winds. Turning on the motor was one option, but isn’t this a sailing boat we are talking about?

The rig

Our rig has a large main and a non-overlapping blade jib. While the latter is excellent for ease of handling, it leaves us under-powered when off the breeze in light conditions. Of course, yachts with large overlapping genoas tend not to suffer this problem. They do pay the double penalty of difficult tacking and too much power in heavier conditions.

For broad reaching we have a big, sexy, asymmetric spinnaker to power the 20 tonnes of steel that is our 14.5m Van de Stadt. After a long assessment it was decided to build a code zero-style sail to power up in wind less than 12 knots. Essentially this is a flat-cut genoa on its own furler. There is no stay to which the sail is attached. The cloth is a laminate made by Dimension-Polyant called PX 10, mixed with PX05. It is a black polyester yarn inserted into a warp-oriented scrim of high-tenacity polyester. The tack is about 400mm above deck level while the clew is elevated about two metres, allowing a view under the sail. Sheets run back to outboard reacher tracks, just in front of the cockpit. The sail is quite large at 115 sqm compared to our normal jib of 45 sqm and main of 70 sqm. Loads develop quickly in the sail so true wind has to be monitored.  

Luff tension

The key to good setting of a sail on a removable furler is luff tension. Because there is no forestay, the luff has a very strong built-in line. We used 7mm DynexDux. It is made of Dyneema fibre and has a seven-tonne breaking strain. Apart from handling loads the great benefit of Dynex is that it resists twisting. This means that when furling occurs, the sail rolls around the line rather than the line twisting upon itself. It is thus referred to as a “torque rope”. The head of the sail is hauled up on a 2:1 Spectra masthead halyard, finished on a winch. The tack is kept mounted to the furler, which itself is snap-shackled to the end of the bow roller. We chose a Profurl endless line furler, rated to four tonnes.

Coiled

When not in use, the furled sail lies coiled like a snake in the sail locker. To set it, we bring it up through the forward hatch onto the foredeck. For ease of movement the normal jib is furled in the usual manner. The endless-line furler is attached at the bow and a spinnaker sheet snapped on at the clew. The still-furled sail is then sent aloft. A sail tie around the sail at clew height prevents early unfurling. The endless furling line is brought aft. The sail can then be unfurled by pulling on the sheet.

Sailing angles vary with wind from about 500 to 1200 apparent. The code zero can be used down to 1500 if the main is not set or is scandalised. Diomedea can do 6-7 knots in 8-10 knots TWS in flat water with this rig.

Furling

Furling the sail is probably the most difficult part of handling. If one has waited too long in a building breeze, then the sail will flog, making furling very challenging. The sail can be blanketed in the lee of the main by running off in this case. One has to be careful not to get wineglass furls in this situation. On one occasion we were forced to drop a partly furled sail onto the deck. It was a big mess. The line used to run the furler should be kept taut. I run our 10mm line through a snatch block shackled to a block and tackle, which itself is made fast to the toerail. This reduces the problem of the sail “running out” as one is furling it in. Furl quickly and smoothly. Once it is furled, I slacken the halyard and unclip the furler from the bow roller. I then guide it into the sail locker and drop the sail while Andrea coils it as it comes down. Unclip the sheet, run out the jib, and Diomedea is away.

What’s in a name?

So why is it called a “code zero”? Probably because of the prevalence of that numeral in the price tag. However, for pure light-wind sailing pleasure, the code zero is brilliant. And, if nothing else, the 2:1 halyard is excellent for lifting a dinghy on and off the foredeck or for taking me to the masthead.

RESOURCES

Halyard rigging by Riggtech:

www.riggtech.com.au

Torque rope by Sydney Rigging:

www.rigging.com.au

Sail construction by Ian MacDiarmid:

www.macdiarmidsails.com.au

More information on Torque rope:

www.strongrope.com/dynex.htm

Sail material:

www.dimension-polyant.com/en/Laminate_Racing_2_4_1.php

Profurl furlers:

http://www.profurl.com

Voyager’s Handbook, 2nd Edition.

Beth Leonard