Self-steering gear
Before the advent of radio control, model yacht racing (started before WW1) was typically contested on long narrow ponds, and the number of stops along the banks was counted as a penalty in the final result.
[2] The Braine steering gear was a fine-tuned system of quadrant on the rudder stock driven by the tension of the mainsail sheet and damped by a rubber band.
Some transatlantic singlehanded sailors used a crude form of self steering devices to cross the Atlantic Ocean in the 1920s and 1930s, the most notable being Frenchman Marin Marie (Paul Marin Durand Couppel de Saint Front) who crossed the Atlantic twice in the 1930s, first on a sailing yacht called Winnibelle II and secondly on a motor pinnace called Arielle.
Self steering aboard Winnibelle II on its Atlantic crossing from Douarnenez, France, to New York in 1933 was somewhat similar to a Braine gear, using twin jibs (Trinquettes jumelles) with their sheets connected to the rudder via an array of blocks and lines.
This auxiliary rudder could be mechanically driven by a special wind vane mounted atop of the coachroof consisting of two rectangular airfoils set at an angle on a vertical axle and balanced by a counterweight.
The Casel autopilot, which included an array of green, red and white telltale control lights, used an electric motor to act on the main rudder.
Though its basic principle was sound and was useful in some sections of the passage, it proved to be somewhat too lightly built for a wet vibrating little boat and was trouble ridden.
Marin Marie, though appreciative in some occasions generally loathed the temperamental device, specially when he discovered that Casel had inadvertently hidden his stores of Bordeaux wine in the autopilot compartment, unwillingly condemning him to a teetotal Atlantic crossing of some 20 days.
The electronics module calculates the required steering movement and a drive mechanism (usually electrical, though possibly hydraulic in larger systems) causes the rudder to move accordingly.
On yachts, the three most common systems are: Depending on the sophistication of the control unit (e.g. tiller pilot, steering wheel attached chartplotter, ...), electronic self-steering gear can be programmed to hold a certain compass course, to maintain a certain angle to the wind (so that sailing boats need not change their sail trim), to steer towards a certain position, or any other function which can reasonably be defined.
As the electronic autopilot systems require electricity to operate, many vessels also make use of photovoltiac (PV) solar panels or small wind turbines on the boat.
As well as their requirement for electric power, many long-distance cruisers observe that electronic self-steering machinery is complex and unlikely to be repairable without spare parts in remote areas[citation needed].
Morris admits to his practice of setting a kitchen timer for a half-hour at a time and sleeping while the windvane steering device controls the helm, even in head winds of 25 to 35 knots.
An immersed area of 0.1 m2 at 1 m lever length at a boat speed of 2.5 m/s (about 5 knots) and 5° angle of attack already generates a moment of 180 N⋅m, when the oar has a NACA0012 profile.
Modern servo pendulum self-steering devices with optimized transmission and low friction mechanics are more and more used for day sailing and cruising; formerly being used mainly for long distance ocean passages.
[15] Joern Heinrich also published a mechanism[16] which uses a fin in the water to compensate for the apparent wind change during the acceleration/deceleration of multihull yachts with larger speed potential like catamarans and trimarans in gusts.
Heinrich applies his own parametric simulation software VaneSim[17] to optimize windvane self-steering devices according to boat properties.
