High seas drifter: The code zero solution

A versatile, light-air sail can keep a heavy-displacement rig moving, or drifting under control, even in a breeze just two knots beyond dead calm. A 100 percent, bi-radial cut, drifter does the job on our Tayana 37 cutter Anna — it’s a lightweight headsail, constructed of 1.5-oz nylon and can be used on the open ocean or along protected coastlines. Upwind, downwind, any time the air gets light.

When our heavier, 9-oz Dacron cruising sails stall out, too heavy to be effective in much less than five knots of breeze, the drifter goes to work; it will fill and hold its shape in the slightest wind. And it’s surprisingly effective over a large range of wind angles: from 45° to 180° off the wind, close hauled to dead downwind.

In very light air, our drifter is certainly our most versatile sail. It can work downwind, as one element in a double-headsail setup (either with or without the addition of the mainsail), and it can work, capably, all by itself. For upwind work, it may be combined with mainsail or mainsail and staysail. And, once again, it can work quite effectively on its own.

With a moderately-sized drifter, the total square footage of the sail plan can be adjusted effectively, in increments. The drifter also has the ability to drive the boat on any point of sail — not just a limited reach — and this is, in our opinion, the biggest draw over that of a large asymmetrical spinnaker (which may be two to three times the size of our drifter and more powerful on a reach, but not nearly as versatile, overall).

A drifter can simply hank on to a headstay without an existing furler. A Solent stay can also be rigged to accommodate a second hanked-on headsail. Our preference was to rig an endless-line, code-zero type furler to handle the job of flying the drifter. Since the drifter has its own built-in stay, of low-stretch Spectra sewn into the luff, all we needed were two additional fittings to rig the drifter: a fitting to accommodate the external block and Spectra halyard, positioned about one foot below the masthead. And a strong padeye fitting, positioned toward the forward end of the the bowsprit, for attaching the tack of the flying drifter.

The code zero furler
We chose the Facnor FX-1500 series, code zero furler, because it is well-engineered, proven technology. In open-ocean conditions, or in gusty channels, straits and sounds, our Facnor code zero furler can be handled by one person, with very little effort. This can be done from anywhere on deck or from the ever-popular safety of the cockpit.

The square footage of the sail will determine the size of the furler (or model number) required for safe working loads. On Anna, the drifter is 450 square feet (about the same size as our heavier 100-percent headsail). The Facnor FX-1500 is rated for up to 590 square feet of sail area, and so it can handle the task with ease. It affords one-handed operation, even under loads imposed by a fresh breeze.

The component parts (both the furling drum and the head swivel) are precision engineered. They are constructed of anodized aluminum and stainless steel. The clever design of the furling drum allows for the endless furling line to remain conveniently in place, on deck, after the sail and furler have been stowed away. The drum, which is grooved, grips the endless furler line without slippage; yet its friction isn’t excessive.

The setup is quick and simple. Quick-release, stainless snap-shackles are built into the head swivel and furler-drum component parts, so the rig is easily connected, disconnected, raised or dropped, all under full control. When the drifter is furled, it snakes down and coils compactly onto the deck or directly into a bag, without the drama of the sail flailing around and chafing on deck, or accidentally slipping over the side into the water.

Drifting in the shipping lanes
The ability to move along on any point of sail, in light air, helps to reduce the risk of collision with commercial traffic that may be restricted to the shipping lanes. Large containerships, cruise ships, tankers, ferries and working tugs are all required to stay within the inbound and outbound vessel-traffic control lanes, as they make their way to and from busy seaports. A sailing vessel is not restricted to the confines of the shipping lanes, and typically tries to avoid being in them when traffic is present. But we sometimes need to cross those lanes; and the quicker the better.

It only takes about five minutes for a loaded containership, moving at 24 knots, to cover two nautical miles. It seems like we have plenty of time to get out of their way when we see them off in the distance. In reality, though, a sailboat drifting in very light air — say, a three-knot breeze — will move only about as far as, say, the length of one of these mega-ships by the time they reach us. Not very far, really.

If a drifter can give us the ability to change our course and keep moving (without a lot of fuss) in any direction, that’s a sail worth having in the inventory.

A minimalist, light-air strategy
Our most basic light-air strategy is to fly our code-zero type drifter. Effective on any point of sail between 45° and 180° off the wind, it’s a no-nonsense, light-air solution that is capable of moving us along at about one half of the apparent wind speed, or better, when the breeze is less than eight knots apparent.

We’re not particularly concerned about moving fast in light air. We simply want forward progress and directional stability. In fact, we’re happy to move along on an ocean passage at four to five knots. And in very light air, moving at two to three knots works for us, too, until the breeze picks up.

A 1.5-oz nylon drifter is durable enough for use on the open ocean, but works for coastal or inland cruising as well. It will fill and maintain a nice shape in as little as two knots of breeze. The only downside to nylon is UV degradation. So, when not in use, it should be covered with a protective sleeve. We simply drop, bag and stow the sail after conditions have shifted to a steady, moderate breeze; when our heavier, more rugged, Dacron cruising sails can take over.

Rigging a code-zero type furler
Code zero furlers are typically located just forward of the fixed headstay. A sloop rig, without a retractable bowsprit, may fabricate a fitting just forward of the headstay; for instance, at the end of a sturdy bow roller. But that isn’t a likely option for a true cutter rig, where bow rollers are located well aft of the headstay, at the leading edge of the deck. This would likely result in the loss of too much sail area for the drifter to be effective.

The code-zero setup on Anna is somewhat nontraditional. We decided to rig our flying, code zero — with its own built-in Spectra stay — slightly inboard of the fixed headstay; just nine inches aft of the cranse collar on the bowsprit. This leaves just enough room for the furled drifter to clear the larger Profurl drum which resides on the headstay.

In our opinion, the tradeoff of positioning the code zero, just aft of the headstay, but still well forward of the leading edge of deck, was negligible: it represented the loss of perhaps 70 square feet of drifter area. If the addition of that amount of square footage had been really important to us, we could have designed and fabricated a strong fitting forward of the cranse collar. But loads imposed beyond the cranse collar would not have been well-supported without additional stays; and we simply didn’t want to add complexity to an otherwise simple rig. By positioning the code zero furler slightly aft of the cranse collar, where the bowsprit is thicker and stronger, we could reduce threats to the integrity of the structure, while under a load.

Another advantage of rigging the code zero where we did, is that we could avoid hanging off the end of the bowsprit to attach or to detach the drifter. In sloppy seas, this would add an extra margin of comfort and safety.

A consideration of wind-loads
We fabricated a strong fitting that would take advantage of spreading the imposed loads over the thickest, strongest section of the bowsprit aft of the cranse collar. Since we couldn’t calculate the exact stress loads on the bowsprit, where it wasn’t supported by stays at the cranse collar, we took a common-sense, educated-guess approach and overbuilt the fitting to give us an added safety factor.

We figured that a beefy, stainless fitting, measuring about 6 inches in width and 3/16-inch in thickness, with a padeye welded to its top surface would work well. The loads imposed by the drifter would first be transferred to this stainless fitting and then spread out over a somewhat larger and stronger cross section of the bowsprit. It would be more effective than through-bolting a padeye and a backing plate. Essentially, our fitting would fully encompass a section of the vertically laminated bowsprit, near the cranse collar, and avoid drilling unnecessary holes into the laminate.

We expected, occasionally, to see higher wind gusts and corresponding forces when using our drifter setup, especially if going towards weather. We’ve since used our drifter in gusting conditions and believe that the extra loads imposed on our bowsprit are, in fact, adequately supported by our reinforced fitting.

The force of the wind on a sail is an easy calculation:
WL = SA x V2 x 0.00431
WL = wind load in pounds
SA = sail area in square feet
V = wind velocity in knots

This gave us a starting point for our educated guess as to the safe working load that could be transferred to an unsupported section of the bowsprit, that is, the section aft of the cranse collar, and before the deck.

Using this formula, we can determine that the forces transferred to a deck, bowsprit or masthead fitting, in light air conditions — say, eight knots apparent — will not be an issue. With winds up to 16 knots, the loads are still rather small. If the fitting is beefy and able to spread the load over an area of at least a few inches, in the direction of the pulling force, then the loads imposed by occasional, unsustained gusts shouldn’t present a problem. If sustained, high winds are expected, then obviously a drifter is the wrong sail to be flying, and we would roll it up in favor of our heavier Dacron, cruising sails.

Wind strength and corresponding forces are exponential. A drifter with a total area of 450 square feet, for example, will exert the following loads:

Wind speed     Load/Force
(knots)            (pounds)
4                       31
8                       124
16                     497
32                    1,986

A light-air, code zero will typically fly in apparent winds of about eight knots or less. In these conditions the loads are minimal, especially downwind. But if a squall or heavy gust catches the sail before you can hand it, the load increases, significantly. So it made sense for us to design a stout setup, as we planned to use our drifter in areas where squalls were likely to be encountered.

The endless-loop setup
The endless-loop (or continuous-line) setup for the Facnor FX-1500 uses 6-mm line that is twice the length of the distance from the furler drum to the location where you’ll be furling the line; most likely the cockpit. The line should be run through the path of the lead blocks or bullseyes for the exact length, and then a little extra should be added to compensate for the continuous-line splice. Attaching the last block in the setup to a bungee cord will give the endless loop the right amount of tension on the furler drum. It will also allow you to stop the line from running free, after the sail is furled, by providing enough slack in the line, for example, to take a wrap around a nearby cleat, which will add friction to the line and keep the sail from accidentally unfurling.

The reduced-volume, end-to-end splice
The continuous-line, end-to-end splice, must pass through the groove in the furler drum without excessive friction. And since the splice isn’t ever under a tremendous load in this application, a reduced-volume endless-loop splice is acceptable. The reduced-volume splice is not as strong as a traditional end-to-end splice, but it is strong enough for continuous-line furler applications.

Once the lead from the furling drum to the cockpit has been laid out, and the number of bullseyes or blocks required for a fair lead are known, they can be pre-threaded onto the furling line before the splice is made. Otherwise, small snatch blocks will need to be used to guide the continuous line, since they can be opened easily to accept the line and then snapped closed, once the line has been passed through.

Since the Facnor code zero furler allows a continuous line to be easily looped around the drum, or removed from the drum, at will, the furling-line setup can remain in place on deck whenever the sail and furler are stowed away. Next time you bring out the drifter, simply loop the continuous furling line around the drum and you’re good to go. Additionally, we run the drifter’s own set of light-weight sheets through the same large rail blocks that we use for the heavy-weight jib; these sheets share the same block and can remain in place, ready for use.

The cost of the code zero furler, size of the lead blocks and length of furling line will depend on a few factors: the size of the sail; the manufacturer of the furler; and the length of the run from the furling drum to the cockpit.

In our setup, a Facnor FX-1500 model, code zero furler fit the bill. The cost was under $1,000 for everything excluding the drifter. A 450-square-foot, 1.5-oz nylon, bi-radial cut drifter is probably one of the less expensive sails in the inventory.

The cost will vary, depending upon the sail loft used. If you already have a hank-on drifter, it can be converted. If the halyard is also Spectra, then sag will be minimal — a necessity for good upwind performance.

Rich and Cat Ian-Frese have been living aboard, refitting and cruising around the NE Pacific Ocean basin, on Anna, since 2000. They plan to leave Seattle and head in the general direction of South America in 2011.

By Ocean Navigator