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System Options
"O<n>=<value>"
The options function provides certain information for the system which can be useful in certain conditions. The argument <n> identifies the option you want to change, and <value> is the new value for that option.
On the T1, all these values are enumerated on the Status1 output.

Set Time Format

O1=0 (HH:MM)
O1=1 (MM:SS)
O1=2 (HH:MM:SS)
+4 displays UTC (T1)
Option 1 sets the TIME display to hours and minutes, minutes and seconds or hours, minutes and seconds. When using UTC, the value of Option 26 is used.

Select Polar & Target Format

O2=0 or 1 or 2
Option 2 sets POLAR & TARGET Boatspeed display formats.
The default value (0) is knots, i.e. the value stored in the polar module. A value of 1 sets the displays to differential knots, i.e., [Boatspeed minus Polar] and [Boatspeed minus Target]. A value of 2 gives Polar and Target as percentage, ie [100 times Boatspeed divided by Polar speed] and [100 times Boatspeed divided by Target speed].

Select Polar

O3=<polar#>
Option 3 overrides the polar selector switch in the polar module, and forces use of a particular polar number for the functions POLAR and TARGET Boatspeed. The setting of this option does not affect the polar number used for "P=" commands (below). Your module has to have more than one polar installed before you can use this function. The default value for option 3 is 0, and causes the system to use whichever polar is selected by the switch on the polar module. A setting of '1' forces use of polar 1 and so on, regardless of the switch setting. If this option and the selector switch are both '0', then the first physically addressed polar is selected. Note that selecting a polar that is not there can cause some strange results.

For the T1, Option 3 selects the polar file (see Polar File Set). The filename is displayed on T1 System Status, “PL”.

Adjust True Wind angle

O4=<offset>
Option 4 adjusts the TRUE wind angle offset. The <degrees> value is added to the true wind angle just after it is calculated, and before it is used. The purpose of this function is to compensate for wind shear by twisting the measured true wind into "effective" true wind (i.e. the wind at the center of effort). Option 4 affects True wind angle, Wind Direction, VMG, Time to the Laylines, Distance Lost VMG, Opposite Tack and Polar and Target Boatspeeds.

This is now generally deprecated because it masks wind shear.

Adjust Reef & Flat

O5=<REEF>
O6=<FLAT>
Options 5 and 6 control the UPWASH function. The default Upwash correction is

Upwash - Reef2 * Flat * Sin2.5(.6*(180-Ba))

Both options default to 1 (i.e. full effect). Reducing Reef or Flat lowers the upwash correction. The reduction is linear with FLAT, and as the square of REEF.

These are now generally deprecated in favor of Upwash slope and AutoCal functions.

Enable Current Calculation

O7=0 or 1
Option 7 controls calculation of CURRENT SET & DRIFT. A setting of 0 inhibits automatic current calculation (and gives Error 75 when the GPS makes an output). A setting of 1 (default) enables automatic current.

Set Mast Height

O8=<mast height>
Option 8 is used for correcting the apparent wind angle and speed for roll rate. The athwartships disturbance is calculated from roll rate and mast height, and removed from the apparent wind. Setting a value of 0 feet eliminates the correction.

Set Light Level

O9=0 to 9
Option 9 controls the lighting level number sent with the lights frame. Matryx and Magnum indicators use this number to control their default lighting level.

Set VMC Option

Option 10 sets the mode for the VMC output.
  • O10=0 (default) causes VMC to be calculated with a rhumbline the same as the waypoint bearing (from a Position device or the W= command).
  • O10=1 causes the VMC to be calculated from a rhumbline input under Option 11.
  • O10=2 causes tag “f” to display COG/SOG based on boatspeed/track and current set & drift.

Set VMC Course

O11=< VMC Rhumb>
Sets the rhumbline course to be used for VMC when Option 10 is 1.

Set Units of Measure

Sets the units-of-measure for Temperature, Barometric pressure, Depth and Distance-Lost outputs. This option is a mask (like Configuration). The "1" bit controls the temperature units in degrees Fahrenheit (O12=0) or Centigrade (O12=1). The "2" bit controls the depth/DL units in Feet (O12=0) or Meters (O12=2). The "8" bit controls the barometric pressure units in Inches of Mercury (O12=0) or Millibars (O12=8). You can combine them by addition (see the table). The default is Fahrenheit and Feet. Also note that the Option Switch in the 001 CPU will set the Master Reset value of O12 to 0 or 3 (see below). The settings are in saved RAM, and remain in effect until the next Master Reset.

This value is displayed on T1 System Status, “UM” and "O12".
O12 Temperature Depth Barometer
0 °F Feet In. Mercury
1 °C Feet In. Mercury
2 °F Meters In. Mercury
3 °C Meters In. Mercury
8 °F Feet Millibars
9 °C Feet Millibars
10 °F Meters Millibars
11 °C Meters Millibars

Set Stopwatch Format

  • O13=0 sets the stopwatch to mm:ss format
  • O13=1 sets the stopwatch to sss format (e.g. -10:00 would be displayed as -600).

Set Current Update Limit

O14=<knots>
Sets the limit that current magnitude updates. Default is 0.1 knot per GPS update.

Set Current Update Percentage

O15=<0 to 1>
Sets the percentage of new measured current to be applied (i.e. smoothing). Default is 0.25 (25%); maximum is 0.999, minimum is 0. To increase response, increase the number.

Substitute COG/SOG for Speed/Hdg

Enable GPS COG and SOG as replacements for paddle and compass + leeway.
O16= Boatspeed source Track source
0 Paddle Heading+Leeway
1 SOG Heading+Leeway
2 Paddle COG
3 SOG COG


Set Compass Lubber

O17=<lubber>
Set the compass offset (lubber line). Input is degrees.

Set Compass Deviation Parameters

O18=<dev.amp>
O19=<dev.phase>
Allows B/C adjustment of compass deviation.

Hdg = Hdgmeasured + O17 + O18 * Sin(Hdgmeasured + O19)

Set Wind Weight

O20=<k>
Changes in wind gradient and density can sometimes prevent boats from making (and sometimes too easily exceed) their target speeds. Option 20 may help correct this by adjusting the true wind speed input to the polar function. The wind value used to access the polar curves is the product of Option 20 and measured true wind speed.

Set Calculation Options
(T1 only)

O21=<option>
Sets a bit field which controls calculation: (add together the bits you want to activate).
O21 When added in, does the following
1 Prohibits ZDA from setting the CPU clock.
2 Turns on retro-apparent (see below).
4 Disables roll rate in true wind calculation
8 Disables pitch rate in true wind calculation
16 Disables yaw rate in true wind calculation
32 Disables Hazen upwash rolloff function. 1.00 is used for all Bt.
64 Causes Lat/Lon to output in CookPos form.
128 Disables the frogeye filter.
256 Disables pitch rate in apparent.
512 Disables roll rate in apparent.
1024 Debug: Reverse roll correction to true wind
2048 Debug: Reverse pitch correction to true wind
4096 Debug: Reverse yaw correction to true wind

Set AHRS Flags
(T1 with AHRS option only)

O22=<AHRS flags>: (add together the bits you want to activate).
O22 When added in, does the following
1 Disables heel output.
2 Disables pitch output.
4 Disables heading output.
8 Disables roll rate output.
16 Disables pitch rate output.
32 Disables yaw rate output.

Set Update Rate
(T1 only)

Sets the T1 processing loop rate.
  • O23=1 (4 Hz. - Standard Rate)
  • O23=2 (8 Hz.)

Set boxcar average
(T1 only)

O25=<N>
Sets the boxcar length to N for boatspeed and apparent wind speed. Default is 7.

Set UTC Offset
(T1 only)

O26=<minutes>
Sets the local offset from UTC (in minutes). If time is set to local (see Set Time Format), Option 26 is subtracted from the internal clock, and time is displayed as HH:MM[:SS]. If time is set to UTC, the internal clock is displayed as HH:MM[:SS]z. Eastern time is +300 minutes.

This value is also displayed on T1 System Status, “TZ”.

Set Command Debug Tag
(T1 only)

O27=<tag-decimal>
When set to non-zero, all commands are echoed on the specified tag. Useful for troubleshooting mysterious command-related issues. Set to 0 on power-up. See System Command Troubleshooting.

ROT correction for Wind Direction
(T1 only)

O28=<factor>
Rate-of-turn * factor is added to the true wind solution to counteract tacking disturbance (experimental: see Mt perturbation).

Control NMEA -> NMEA channel
(T1 only)

O29=<0 or 1>
Enable (1) or disable (0, default) transferring NMEA input transfer to the high channel.

Set Boat Name
(T1 only)

O30=<boat name>
Helps identify boat name in log files. Name appears in the Status 1 list as BN: and as O30=.
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