TECHNIQUE Quick guide to the use of threads and windmarks

Sithout them, you don’t go anywhere. Even on the most extreme racing boats, even on TP52s (photo above) or flying AC75s, they are never lacking. They are the famous “fillets”.

GUIDE TO THE USE OF FILLETS AND WINDAGE MARKERS

We will call fillets those strands, made of wool or nylon, attached to sails for the purpose of showing wind flow near the surface. By wind markers, we will mean instead the tapes installed on the superstructures, designed to indicate the direction of apparent wind at that point. We will consider, in the following examples, keeping a steady course, and wanting to maneuver to set the sails. Here is our guide to using a basic tool for sailing.

ON THE MAINSAIL,

THE FILLETS ON THE LEECH

ARE THE MOST SIGNIFICANT

On the mainsail, the fillets should be installed on three lines: along the leech, in the middle part, and near the luff. The threads placed along the leech, at the height of the batten pockets, are the most significant: they allow the assessment of the airflow out of the entire sail, thus giving the overall picture of the performance of the entire mainsail.

You start the set-up from the uppermost leech fillet, near the pen, by maneuvering the mainsheet. In succession, acting on the vang, you will spin the other threads correctly on the liner. The high batten should be almost parallel to the boom. In tight winds, the liner will tend to vibrate, making thread reading impossible. In addition to caulking the vang, one must therefore tension the duet, the selvage inside the sail that adds tension and rigidity to the leech.

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TO ADJUST THE “FAT”

The fillets in the middle part of the mainsail are installed upwind and downwind. They are useful for adjusting the shape of the mainsail and indicate the presence of turbulent rejection of the headsail.

Middle fillets assume significance when observed all together, identifying areas that are too fat or too thin. If, for example, the sail fat is too low, the downwind fillets of the lower part will tend to fall off; tensioning the mainsail base will be the first maneuver to improve the profile.

FILLETS AT THE LUFF, FUNDAMENTAL ON DRIFTS AND CAT

The threads near the luff indicate the flow at the angle of attack of the sail. They are mainly used on fast boats and dinghies, where the cunnigham greatly modifies the sail shape in this area. On rotating mast catamarans, they help orient the mast and full-batten battens. They also serve for achieving voluntary stall: in high winds, in fact, on catamarans where you cannot reef, you reduce lift by counter-rotating the revolving shaft until the threads near the luff all go into turbulent motion.

ON THE HEADSAILS

In addition to indicating the correct angle of incidence as shown in the quick start guide on these pages, the threads near the forestay allow the sheet point to be adjusted. If the windward fillet near the pen moves upward, the sheet point should be advanced; vice versa, the sheet carriage is retracted. On Code0s, the fillets are already placed by the sailmaker at strategic points so as to clearly indicate to the crew when the sail has the optimum angle and shape to provide maximum thrust in low wind conditions.

FOR SPINNAKER AND GENNAKER

Spinnaker and Gennaker are already a giant thread in themselves. The good bowman, observing the trailing edge, maneuvers the sheet. Lasca, seeking maximum extension and abrupt cocking as the ear forms on the leech, seeking balance between these two points.

On the spi, if the flow is laminar at the inlet, it will propagate, because of the spherical cap shape along the entire surface. Therefore, it is useful to install, in addition to the fillets on the sail, wind markers on the tangon to indicate the correct angle of incidence of the apparent wind, which must always be perpendicular to it. On the gennaker, the fillets are similar to those on the jib. The analysis of the fillets on the load-bearing sails, should also be extended to the fillets on the other sails, to detect turbulent interactions. On gennaker dinghies, where there is no jib luff, the wrong position of the headsail will greatly impact, for example, the downwind spinnaker threads, while a mainsail that is not on target will drastically frustrate the outflow of a spinnaker.

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THE TRICK OF MAGNETIC RIBBONS AS A WEATHER MARKER

Electronic anemometers and Windex gauges have lost the tradition of attaching a long ribbon to the top of the mast as a wind marker. This remains in use only on radio-controlled classes. However, the tapes, often made from old cassette tapes and mounted on the low shrouds, are useful in a number of circumstances for some tricks. In port, they identify wind turns not present at the top of the mast: wind impacting the hull will be the most important one to consider in maneuvering.

When there is a flat calm, the direction of the first wind burr is better identified by the windward marker tapes than by the windex, which is more sensitive to roll and pitch. Painting the ends of them with fluorescent paint is a trick to make them more visible even at night, then there are those who claim that the noise of the windmarks made by old VHS tapes or aluminum tapes, is a good deterrent for birds.

TO SUMMARIZE: GUIDE TO THREADS IN BRIEF

SAILS OF PRUA.

Here the fillets indicate the correct incidence of the forward part of the sail with respect to wind; they are mainly affected by the tension of the jib sheet. Let’s look at the example of upwind (red) and downwind (dashed green) threads, sailing with port tack.

– A – Threads parallel to each other: = OK, in that area, the headsail is on mark, correct angle of incidence and attack, the flow is laminar coming in both upwind and downwind.

– B – The upwind upwind fillet, the sail is too caulked and chokes the wind, generates much heeling and little progression, the jib sheet needs to be let go.

– C – Windward fillet falls down = sail does not carry, is too loose, need to caulk sheet.

Of slack, this situation is preamble to jibe!

– D – Threads in an erratic position = non-laminar and turbulent flow, sail angle is deeply wrong, shape is exaggeratedly flat or fat, eddies form, or the sail is already receiving turbulent flow such as the rejection of a gennaker or spi.

RANDA

– Balumina: They indicate whether the angle of incidence is correct, and whether the overall outflow of air is laminar. They have to spin Parallel to the slats. They are adjusted starting from the top one, acting mainly on the sheet.

– Middle area: upwind and downwind, indicate whether the sail fat is well positioned. With fillets of the lumina already on the mark, They suffer from baseline tension, vang and cunningham. Downwind, they also indicate turbulent rejection of the over-capped headsail.

– Inferring: Flow information at angle of attack, reflect the effects of cunnigham on dinghies and fast boats. On revolving-mast catamarans, they allow adjustment of lift or indicate the point at which voluntary stall is reached to reduce power.

SPINNAKER AND GENNAKER

– On the spi they are useful in combination with windmarks on the tangon, which must be perpendicular to the incoming wind.

– On the gennaker, especially those downwind, indicate turbulent interactions generated by the jib that nullify the gennaker’s lift in faster gaits.

FOCUS – FOUR SOLUTIONS FOR FILLETS AND WINDMARKS

Tape markers for shrouds. These rigging marker tapes, sold in pairs, red and green, are nylon with Velcro closure. They cost 13.45 euros. FIND THEM HERE.

Sail marker threads. This is the giant Plastimo’s solution for wind markers on sails: they are fastened quickly using an adhesive disk, with no need to puncture or sew the sail. They cost 12.81 euros. FIND THEM HERE.

The classic “flag.” Another solution is this Levante wind mark flag, ideal for small boats or superstructures. Applies to the side of the shaft, with bayonet bracket. Balanced with counterweight, it is priced at 12.99 euros. FIND IT HERE.

“Digital” threads. Trimcontrol e-telltales are actual electronic threads that send data to on-board instrumentation and even to an app on your cell phone. Battery-powered, they are installed on sails like classic ones, sending data to the control unit up to 4 times per second. Price is by request. FIND THEM HERE.

Report by Luigi Gallerani