Offwind can write back to the instrument network, so the boat's own displays show what only Offwind works out: target boat speed and angle, polar percentage, current set and drift, time to the layline, and fields you define yourself. It can also send the active waypoint and route to a plotter or autopilot that follows them.
Nothing is ever sent until you turn it on, twice: once for the boat, and once for each connection.
1 · Allow it for the boat
- Open the boat's output. Under Boat, press Derived fields and output.
- Turn it on. Under Output to instruments, turn on Send data to this boat's instruments. It is off for every boat to start with.
- Heading. Turn on Allow sending heading only if you want Offwind's heading on the network. Leave it off when the boat has its own compass.
- Race rules. Withhold forecast values in race rules mode is on to start with. Leave it on for races that forbid outside weather help: the forecast next-leg values are then not sent while race rules mode is on.
2 · Turn it on for a connection
- Open the connection. Under Boat, press Connections, then the gateway that feeds the displays.
- Enable output. Under Output to instruments, press Enable output on this connection…. The first time, Offwind shows Sending data to your plotter: data it sends is computed from other sources and may be wrong or late, and it never commands an autopilot. Press I understand.
- Name the destination. Type what it feeds in Sends to (e.g. Zeus plotter).
- Rate. Set Rate between 0.2 and 5 per second. Once a second suits most displays.
- Choose the values. Turn on what to send: Target boat speed, Polar %, Target TWA, VMG, Current set and drift, Next-leg TWA (forecast), Next-leg TWS (forecast), Time to layline. To send anything else, such as one of your own fields, press Add a value to send under Values to send.
- Start. Press Start output. The connection's row in the list shows Output on, and a banner across the top of the Instruments screen reads Sending to and the destination.
On NMEA 0183, Talker ID (blank: automatic) picks the two letters the sentences go out under. Left blank, Offwind chooses one no other device on that connection is using.
Send the active waypoint and route
For a plotter or autopilot that follows a waypoint from the network:
- Allow it. In the connection's output settings, turn on Allow sending the active waypoint and route.
- Send it. With output running and a route active, press Send to plotter/autopilot.
- Stop it. Press Stop sending to plotter/autopilot.
Offwind sends navigation data only: the waypoint, the route, and bearing, distance and cross-track error to it. It never sends autopilot commands. The autopilot and the crew stay in charge.
Your own fields
A field is a value worked out over a time window, such as the 30 second average of true wind speed or the trend in true wind direction. Under Derived fields, press Add a field, then choose Source, Function and Window. Fields are recorded with every session, can be shown on the cockpit's pages, and can be sent like any other value.
Stop everything
Stop all output in the banner, or Stop all output now under Derived fields and output, stops every connection at once. Output also stops by itself when the values it sends go stale, when the connection drops, and when the app closes.
What each connection can carry
- NMEA 0183 carries every value above, and the waypoint and route.
- Yacht Devices RAW, Actisense RAW ASCII and Actisense NGT binary carry current set and drift, and the waypoint and route, onto the NMEA 2000 bus.
- Signal K carries target boat speed, target TWA, polar %, VMG, and current set and drift, and bearing, distance and cross-track error to the active waypoint.
- Actisense N2K ASCII, Orca Core and the Calypso wind sensor cannot carry output.
If a value you chose cannot go over a connection, the output settings say so under This connection cannot carry:.
Limits
- Offwind never sends your position, and never sends a value back to the connection it came from.
- Automatic connections always start with output off.