Graphical Display Optimum ‘Wing Sail’ Mast Angle Based on ‘Wing Sail Polars’, Boat Heading, ‘True Wind’ Data

By James Henderson
FLIR Systems
James.Henderson@raymarine.com

Summary
The goal is to graphically display the optimum ‘wing sail’ mast angle based on ‘wing sail polars’ and the boat heading combined with ‘true wind’ data. Using the wing sail software, we can display the current wing sail angle derived from a mast rotation sensor and data derived from true wind, heading and other data such as:

– Wind speed and direction (True wind speed/angle calculated via our airflow & stabilization corrections / speed through water)
– Boat speed (paddlewheel) thru the water & heading
– Position + SOG/COG from GPS
– Boat speed + SOG/COG can determine current
– Wing sail angle (mast rotation sensor)
By utilizing the above data in conjunction with the ‘wing sail’ polar data, the optimum wing sail angle can be displayed for the current heading. The sail angle can then be adjusted by trimming to achieve the optimum angle or using an automatic drive, if required. Novice sailors as well as experienced racers will benefit, and it can be used for training users to select the best sail angle for given heading and wind conditions.

Description
Modern race boats use a wing sail, this is a fixed sail (similar to wind surfing) where the mast is rotated to select the optimum sail angle for given wind direction and heading. Selecting the optimum sail angle is currently dependent on experience and ‘tacking’ the angle to achieve the fastest and most efficient use of the wind. As the wind fluctuates or heading is changed and other variable such as tidal currents come into play and the wing sail angle needs to be constantly changed. This requires great skill and experience. The wing sail graphical display removes the requirement of skill and experience by displaying the current and optimum sail angle on a display.

The wing sail software outputs a graphical display of the current wing sail mast angle and optimum wing sail mast angle, based on ‘true wind’ heading and wing sail polar data for race boats that use a wing sail. This is a fixed sail (similar to wind surfing) where the mast is rotated to select the optimum sail angle for given wind direction and heading.

Selecting the optimum sail angle is currently dependent on experience and ‘tacking’ the angle to achieve the fastest and most efficient use of the wind. As the wind fluctuates or heading is changed and other variable such as tidal currents come into play; the wing sail angle need to be constantly changed and this requires great skill and experience. This system would remove the requirement of skill and experience by displaying the current and optimum sail angle on a display. The display will use sensor data to calculate ‘true wind speed and direction’ this can then be combined with heading, the current wing sail angle (from a mast rotation sensor) and wing sail polar data to calculate the optimum wing sail angle for the fastest and most efficient sailing.
The wing sail software uses the combination of ‘true wind’ (actual wind speed and direction that would be experienced by a stationary object) combined with the performance characteristics (look up table) of the sail polar data: the present sail angle and heading are then used to calculate the optimum sail angle, for the current heading.
The above calculations are using software with a combination of external data inputs; these include: GPS instruments, adjusted wind vane measurements and speed though water sensors, to calculate the above true wind speed and direction; when this data is combined with the current heading (where you are going) and the wing sail angle (from a mast rotation sensor) plus wing sail polar data look up table, the software calculates the optimum wing sail angle for the fastest and most efficient sailing and displays and wing sail angle corrections graphically, as the example shown below:
Then the software provides a graphical user output of current sail angle and the optimum sail angle.

flir
The current could be shown in full and the optimum as a ‘ghost’ image (faint or dotted lines) when the sail is adjusted for angle (trimmed) manually or automatically, to line up the aforementioned images, the display then changes to display they are aligned with a graphic ‘icon’ or change of color or line thickness to display optimum angle has been selected.