If you've found yourself scratching your head at sailing terminology as the America's Cup hits fever pitch, AUT's Sailing Professor Mark Orams is here to help.
With more interest than ever heading into the final days of racing, here's a guide from Orams to help you decode the language usedin this year's event:
Starboard (tack or gybe)
The yacht is sailing with the wind coming from the right side of the boat (when looking forward). This is important because in the rules of sailing a yacht on starboard has right of way over the yacht on port.
The yacht is sailing with the wind coming from the left side of the boat (when looking forward). When sailing on port you must give way to the yacht sailing on starboard.
Windward
The yacht sailing closer to the direction of the wind when compared with their opponent.
Leeward
The yacht sailing further away from the direction of the wind when compared with their opponent. The leeward yacht when it is overlapped with the windward yacht has right of way. As a result the windward yacht must keep clear of the leeward yacht. The leeward yacht can turn up (called a "luff") and the windward yacht must turn in response to keep clear.
Layline
The layline is the angle to the next mark which means the yacht does not have to do any more manoeuvres to reach that mark.
Upwind
The yacht is sailing at an angle to take it towards the wind direction (legs 1, 3 and 5 in these America's Cup races).
The yacht is sailing at an angle to take it away from the wind direction (legs 2, 4 and 6 in these America's Cup races).
Bear away
The yacht turns away from the direction of the wind (this typically means the yacht will pick up speed).
Turning up (or luffing up)
The yacht turns towards the direction of the wind.
Tacking
The yacht turns towards and through the direction of the wind so that the yacht changes the wind from coming from one side of the yacht to it coming from the other side. This means the sails must invert in their shape to retain their aerofoil shape presented to the wind.
Gybing
The yacht turns away from the direction of the wind so that that the yacht changes the wind from coming from one side of the yacht to it coming from the other side. This means the sails must invert in their shape to retain their aerofoil shape presented to the wind.
VMG (Velocity Made Good)
The speed the yacht is making towards the direction of the wind (when sailing upwind) or away from the direction of the wind (when sailing downwind). This is an important indication of which yacht is faster overall (as opposed to which yacht is faster through the water).
VMC (Velocity Made to Course)
The speed the yacht is making towards the next mark. This is the most important data – but we are not seeing VMC reported on the television coverage.
Wind shift
The wind direction is never constant. As a result the angles the yachts can sail vary according to the wind direction changes. Getting "in phase" with the wind shifts means you are using the wind-shifts to your advantage by being on the best angle to the next mark.
The term sailors use to describe wind-speed increase or decrease. So called because of the pressure created on the sails. Increased pressure = more power = equals more speed so sailors are always hunting for this (especially in light winds).
Gas (or "gassing him", or being "gassed")
The turbulent wind coming off the back of your opponent's sails is hitting your sails and causing you problems and slowing you down.
Cant
The angle of the foils in the water (and/or the angle of the hull and mast compared with vertical).
Pitch
The angle of the elevators (foil wings) on the bottom of the rudder which determines the angle of the hull relative to the water when flying (that is, bow down or bow up). This is controlled by the offside helmsman on Luna Rossa (hence the verbal "my pitch" handover call when they tack or gybe). On TNZ this is controlled by Blair Tuke.
"Trav" (traveller)
The track that adjusts the mainsail angle relative to the centreline of the yacht. This is like the accelerator and needs constant adjustment. Powered by hydraulics, the grinders need to keep the pressure up in the accumulators to allow the helmsman to adjust this when he needs to.
"JK"
A manoeuvre that is a bottom mark rounding which leads straight into a tack (this needs both foils down). Named after American sailor John Kostecki.
Jib
The triangular sail that is set at the front of the yacht. The teams have a range of jibs with differing sizes and shapes which are designed for different wind strengths. They are coded J1 (for the lightest wind strengths) up to J6 (for very strong winds). The teams leave their decision on which jib to use up until the last possible minute – it is one of the few things they can change between races.
Flaps
Each hydrofoil has a flap at the trailing edge which is used to control the flight ("ride-height) of the yacht. The flight controller adjusts these constantly to ensure the foiling yacht is stable in its flight.
Mode
Each yacht has a configuration and angle to the wind at which it performs its best. Being able to sail your own mode is important and the leading yacht is able to do this, while the trailing yacht is often compromised by what the leading yacht does. Luna Rossa has been using this to good effect when leading by forcing TNZ to sail a mode which compromises their speed.
"Smack him", "Face him", "Ping him"
The range of terms used to describe when the leading yacht deliberately tacks directly in front of the trailing yacht to cast their disturbed wind (gas) over them and slow them down.
"Lee bow"
When a yacht is deliberately positioned just ahead and slightly to leeward of another boat. This is a move which allows the yacht to "squeeze" (sail closer to the wind) and force the disturbed wind over the yacht behind. Luna Rossa uses this move very frequently when in front of TNZ because Luna Rossa has a better "high-mode" (sailing closer to the wind direction) than TNZ.