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Calibration Functions

The Ockam system calibration functions display the current values of the corrections being applied to the system functions.

Read the Overview.

True wind correction

This is a calibration that adds or subtracts from the magnitude of the true wind angle. If the true wind angle is too narrow (too small in magnigude), wind direction will head when you tack. If it’s too wide (too large in magnitude), you will be lifted when you tack. QuikCal adds or subtracts an adjustable number of degrees from the magnitude of the true wind angle; for a positive 2.0 QuikCal, 21 degrees becomes 23, and –21 degrees becomes -23.

Cal Boatspeed Master & Offset

The overall calibration of Boatspeed is set by the interface signature switch and the CAL Boatspeed Master or the K1 command or AutoCal. If a heel is available, Boatspeed is modulated by heel and CAL Boatspeed Offset.

Cal Leeway

This calibration is the factor used in calculation of leeway angle (See Leeway function). The leeway calibration is set to zero when shipped from the factory, so the leeway will always be zero until you are ready for it. Since leeway and upwash are compensating errors in true wind angle, you should go about adjusting both of these functions at the same time.

Cal Windangle Offset

Zeros the apparent wind angle. A value of 1.0 makes windangle apparent 1 degree narrower on starboard and 1 degree wider on port. A value of -1.0 does the opposite.

Cal Windspeed

Changes the apparent wind speed. K1=1.00 is 100% of the nominal calibration of the signature switch calibration. K5=0.99 lowers windspeed apparent 1%, while K5=1.01 raises it 1%.

Cal Upwash & Upwash Slope

The wind is bent by the sails as it approaches them. In fact, the drive created by the sails is caused by this bending. However, if the masthead is inside this disturbed flow, it is not reading the proper angle and speed. This effect is termed upwash and is a complicated concept to understand.

Upwash broadens (>0) or narrows(<0) the apparent wind angle upwind. Since apparent wind angle has a 3:1 effect on true wind angle (and therefore wind direction) upwind, Upwash is the calibration to use to set upwind wind direction.

Upwash slope is a calibration number that changes Upwash with True Windspeed. The complete Upwash function is


(tag ‘l’) is the angle between the ship’s heading and the boatspeed resulting from side pressure by the sails, resisted by the keel. It is used in true wind and dead-reckoning calculations, and is displayed as an aid to proper calibration. Leeway is calculated from heel angle, boatspeed and Leeway Cal.


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