ATechnical Reference Tools

A.1Wind-range tuning matrix

The matrix is a table of hypotheses, one column per wind band and one row per control, each cell holding the setting the crew expects to be fastest in that band on flat water. Very little of it can be sourced. The class tuning guide places the jib sheet in the middle hole and the track pins in the innermost holes for winds up to about 12 knots and flat water, and holds cap shroud tension at the baseline up to about 11 to 12 knots, then "progressively tighter to flatten the mainsail for progressively stronger winds" S13. No published 49er rake table by wind band and no published 49er polar exists in the fact base, so for every other column the crew's own logged values are the reference, and the cell reads crew value until the log fills it. The guide's jib settings are for flat water; in chop the A.2 row governs.

The mechanisms behind the columns are published. Cap shroud tension controls headstay sag, and sag makes the jib fuller S33. Mast bend flattens and depowers the mainsail, and diagonal wrinkles from clew to luff show over-bending S33. Luff tension induces mast bend and reduces power to the rig, and it is easy to over-vang the mainsail, which induces more mast bend than luff curve S12. Cunningham moves draft forward, outhaul flattens the foot, and downwind the vang controls leech twist once the mainsheet no longer pulls down S34. Rake is set for helm balance: raking the mast aft creates weather helm, and the target is 3 to 5 degrees of weather helm in moderate conditions S32. The lowers set the bend low in the mast; no published 49er figure covers them, so the crew calibrates them by sighting the mast. The crew's own dock readings with the mast stepped and no sails, taken on the same gauge every time, check that the rig has not moved between sessions; the baseline they are read against is the crew's own logged crew value.

The crew fills the matrix only from the recording sheet in A.4. A cell changes when a session row in that wind band, carrying a speed reference, shows the new setting faster than the current one; a setting sailed but not compared stays in the A.4 comment column. Each edit produces a new version, numbered and dated, recording the mast, sail set, foils and combined crew weight it was tested with, since a new mainsail or a change in crew weight invalidates the rows tested with the old ones. Old versions are kept, so that a loss of speed can be traced to the edit that caused it. The band edges are the crew's own: they sit where the log shows the limiting factor changing, from power to righting moment to control, and the class guide's figure of about 12 knots S13 is kept as a reference mark beside the crew's edge rather than as the edge itself. A version is valid when either sailor, or the coach, can set the boat from it at the dock without asking a question.

A.2Sea-state and wave-mode decision matrix

The row is chosen from the physics of the water, not from the wind band. Wind waves grow with wind speed, duration and fetch until the sea is fully developed S71S72; swell is wave energy that has travelled out of its generating area S71 and arrives with a period unrelated to the local wind. In deep water the phase speed is c ≈ 1.56 T metres per second S73, so a long-period wave outruns the boat and is steered as moving terrain, while short chop is met many times a minute and is sailed through. Where the depth falls below half the wavelength the waves slow, shorten and steepen S72, and a wave breaks once its steepness exceeds about 1:7 S74; wind against current raises wave height above normal and wind with current lowers it S76. A leftover sea running at an angle to a new breeze puts one tack into the waves and the other across them, and each tack then needs its own mode S77. Each cell below is a departure from the A.1 column for the wind band; where a cell adds nothing, the A.1 setting stands.

The row is selected before the start from the observed wave period, the wave direction relative to the wind on each tack, and whether the sea is still building or is leftover; it is re-selected at the top and bottom of the course when the sea differs between the two ends, as it does with a shoreline, a shoal or a current line at one end. A mode is a package: the upwind and downwind columns are sailed together with the trim, steering and crew-position columns that belong to them, and a change of mode is called by name so that both sailors move at once. The row and any mid-race change are logged on the A.4 sheet against the settings of the day. The testable standard is that an observer following the boat through a tack in a sea that runs across the wind on one tack sees the trim, the steering rhythm and the crew's fore-and-aft position change at the tack, and change back at the next one.

A.4Rig-settings recording sheet

One session produces one row, and the row is the only path by which a number reaches A.1 or a mode choice is confirmed in A.2. The fields are chosen so that the row can be reproduced: the conditions, every setting, the equipment the settings were carried on, the reference the speed was judged against and the result. Settings are written before launching, any change on the water is written with the time and the reason, and the result is written at the debrief from the logger where one was carried. Class rule C.5.2 permits timing devices, up to two compasses without functions beyond heading, heading memory and timing, camera and sound recording equipment, and tracking equipment where permitted by the ICA, Notice of Race and Sailing Instructions S3; the Vakaros Atlas 2 logs at 2, 5 or 10 Hz and reports VMG and shift tracking S79, and the Sailmon MAX records boat speed, heading, heel, pitch and position S80. At Paris 2024 voice, radio and data transmissions were prohibited from the first warning signal to the end of the last race of the day S4, so on race days the reference is read after racing, never during it. Where an event publishes tracking, the race row also carries the published per-boat metrics, average speed over ground, leg VMG, number of manoeuvres and cross-track error, the extra distance sailed upwind from the course middle line S78S17, so that a race result can be read against the settings of the day in the same units as a tuning result.

Three rules keep the sheet honest. A blank cell is a blank, never a guess, and a later reader treats it as unknown. A row without a speed reference cannot change A.1, whatever the crew felt on the water, because feel is the quantity the sheet exists to check. A change made on the water without a time and a reason is written as unknown for that leg. The standard is reproducibility: either sailor, given the row a month later, can set the boat identically and describe the conditions it was tested in, and the coach can tell from the row alone whether the result is a test or a calibration.

A.5Equipment inspection and maintenance checklist

The class rules make damage prevention a scoring matter. Hulls, hull appendages, rigs and sails are manufacture controlled, and a crew is allowed one hull, one set of spars, one daggerboard, one rudder blade and one mainsail, jib and gennaker per event unless lost or damaged beyond repair S3; a failure at an event is therefore a retirement or a request to the jury, and a repaired part is one whose tuning must be re-established. The mast carries a combined crew weight of up to 165 kg from its dual trapeze S9, and that load passes through the trapeze wires, the hounds, the spreaders and the shrouds every time a sailor goes out. Three inspection categories apply. Daily means on every sailing day, before launching and after the rinse, by eye and by hand without tools. Weekly means one session per training week with the mast lowered where needed, the foils out of the boat and the gauge on the wires against the crew's own logged readings with the mast stepped and no sails, crew value on each wire. Pre-event means a full strip, measure and replace-on-doubt pass completed before the event's equipment inspection, including the hull weighed against the 94.0 kg minimum including wings of class rule C.7.3 S3.

The checklist is worked in the same order each time and signed by the sailor who did it; a finding goes into the maintenance log with the date and the action taken. Anything that fails a daily check is put right or replaced before the boat launches. A replacement of a wire, a spreader, a fitting or a foil triggers a rig re-measure, and the A.1 version in use is annotated with the date of the change, because a new wire settles and the tensions the matrix assumes drift with it. The pre-event pass is finished before the equipment inspection so that a part which fails is replaced within the crew's own control rather than under the event's replacement procedure S3. The testable standard is that over a season no failure the checklist covers occurs on the water, and that every replacement is planned from a logged finding rather than forced by a breakage.