1. For most of us, the optimal sheeting angle (the angle formed between the boat’s centerline and straight line from genoa lead to the sail’s tack), lies between 10 and 15 degrees, depending on the design of the underbody and condition of the sails and bottom fouling. In the figure above, the advantage of a tight 7.5 degree sheeting drops off when the true wind angle is greater than 40 degrees. Most cruising boats lose drive when sailing angles are less than 45 degrees. The vertical dashed lines represent the optimal sheeting angle for that true-wind angle.
When setting up a floating lead system, you need to establish the maximum range of positions you may need. With a track system, the range of placement is limited, but with floating leads the sky is the limit. Make sure the anchor points are where they need to be.
INBOARD/OUTBOARD LOCATION
Historically, a narrow 7.5-degree sheeting angle was considered essential for good pointing ability. While this can make sense for a deep-keeled racer, it doesn’t apply to the typical cruising boat today, and certainly not to shoal-draft cruisers and most multihulls. The optimum pointing angle is determined not by when the jib luffs, but rather by the best tradeoff between the ability of the keel and rudder to resist leeway while creating drag, and the ability of the sails to provide forward drive, while limiting heeling and more aerodynamic drag. If you have a wider sheeting base that is greater than 7.5 degrees, don’t assume the designer got it wrong.
PERFORMANCE
How can a few degrees change the driving force so much? The answer is deceptively obvious— 15 degrees is twice as much as 7.5 degrees, and thus nearly twice as much of the driving force is pointed in the right direction.
2. The floating lead on this Beneteau is adjustable in three dimensions, forward-aft, inboard-out board, and up-and-down. Note the outboard turning block can be positioned more forward for use when the jib is furled.
A boat that has an efficient keel and plentiful sail area can accept this trade-off in exchange for a shorter distance traveled to the weather mark. In a good breeze they’re sailing near hull speed anyway, so more power won’t increase speed much.
A shoal draft cruiser, on the other hand, with a less efficient keel and a shorter mast, will be better off with a 10-15 degree sheeting angle, generating more power and less drag. More water flowing over their stubby keel means less leeway. All that a narrow sheeting angle and higher pointing would do for them is make them crab sideways, loosing speed and not pointing very high when measured over ground.
After considerable testing, in a range of wind and wave conditions, we determine the best average sheeting angle for our 34-foot PDQ catamaran is 12 degrees and the best angle for our F-24 trimaran) is 11 degrees.
The PDQ boat test has lengthened, streamlined keels, so it can out-point most cruising cats and match most cruising monohulls, but it has a shallow draft and is faster up wind when sailed just a little free.
The F-24 trimaran test boat has a deep centerboard and makes little leeway, but it is still faster to weather tacking through 90-100 degrees than pinching up higher. The best angle will depend on boat the boat’s sailing characteristics and the weather (waves, high winds, and very light winds reduce pointing). You’ll have to experiment.
The floating jib lead on this F24 trimaran is adjustable in three dimensions, forward-aft, inboard-out board, and up-and-down. Note the inboard control line leads through a fitting (with a Delrin bushing insert to reduce friction) that rides on the genoa track.
OFF THE WIND
The maximum sheeting angle for reaching with the apparent wind on the beam is about 45 degrees, generally attainable only on trimarans. However, 25 degrees is good and is attainable with reaching sails on most catamarans and racing monohulls using reaching struts. It is also practical on monohulls with non-overlapping head sails sheeted to the point of maximum beam.
Again, the best angle depends on the boat and the weather. Unless there is a reason not to, the outboard lead should be as far out as possible. It should also be farther forward than the windward setting, since the clew has moved forward.
Obstructions complicate matters. Shrouds can get in the way. On the PDQ, the only way to point high was to roll up enough of the genoa to clear the cap shrouds and haul inboard. On many boats with wide shroud bases, the best windward solution is often a partially furled headsail and an inboard/outboard sheeting system. This is awkward but effective.
CONTROLLING TWIST
The floating lead’s fore-and-aft position and/or the vertical height off of the deck is what helps control twist.
If the ring is far aft (or high), the sheet pulls the foot flat but allows the top of the jib leech to twist off to leeward. Moving the lead far forward eliminates twist and makes the sail more full.
Sailors who use roller furling to reef in stronger winds need to be aware that ideal lead position changes as the sail is reefed. The required adjustment to achieve ideal shape will depend on the shape of the sail. High-footed jibs are less affected by partial furling than tall blade sails with deck-sweeping foots.
The genoa on my PDQ catamaran had a high foot, and small changes in fore-aft lead position did not have a significant impact; the same lead position was acceptable from 130 percent genoa to just a handkerchief. My F-24 has a low-footed blade jib and is very sensitive to fore-aft position. If I take in one turn on the furler, the lead needs to move forward a corresponding amount.
TEST N0-DRILL OPTIONS FIRST
Before drilling more holes in your deck, try using existing hardware for your new adjustable lead. On our F-24, the existing track was as far inboard as we would ever want, so we attached the inside anchor point to a supplemental slider set at a forward location on the track. This kept adjustments intuitive; when reefing we simply moved the lead forward by hauling on just one line, rather than balancing the tension between two lines.
An optional anchor point would be a U-bolt just forward and inboard of our slider. This would allow in-hauling without having to drill holes. We also could have anchored to the mast base, although this may be too far forward on some boats.
The outboard anchor is at the extreme beam where an existing U-bolt existed—a location that allows far more outboard adjustment than we need. Monohulls with toe rail tracks or slotted aluminum toe rails will have plenty of outboard attachment options.
When selecting anchor points and running control lines, consider whether you are crating new tripping hazards. Follow existing lines, cabin chimes, and deck edges as much as possible.
Racers like floating leads because they are fast and easy to adjust, allow infinite adjustment in all directions, and are feather light. But even the dyed-in-the-wool cruiser can appreciate their simple reliability and adaptability for roller furling genoas.
