@rob42 reported that Sailgauge doesn't work with plain ws server, because it tries to load and use primus from the server.

npm run build fails with

ERROR in ./~/signalk-client/index.js
Module not found: Error: Cannot resolve module 'mdns' in /Users/tjk/git-workspace/signalk/sailgauge/node_modules/signalk-client
 @ ./~/signalk-client/index.js 156:15-35

ERROR in ./~/signalk-client/test/url.js
Module not found: Error: Cannot resolve module 'chai' in /Users/tjk/git-workspace/signalk/sailgauge/node_modules/signalk-client/test
 @ ./~/signalk-client/test/url.js 1:11-26

ERROR in ./~/tv4-formats/index.js
Module not found: Error: Cannot resolve module 'validator-js' in /Users/tjk/git-workspace/signalk/sailgauge/node_modules/tv4-formats
 @ ./~/tv4-formats/index.js 20:20-48

ERROR in sailgauge.js from UglifyJs
SyntaxError: Unexpected token: name (PerMessageDeflate) [./~/ws/lib/PerMessageDeflate.js:19,0]

The java server needs a subscription request before data is sent. Line 115 of index.html

connection = new WebSocket(theUrl);
connection.onopen = function (msg) {
// console.log("open:" + msg);
//send sub
var sub = {"context":"vessels.motu","subscribe":[{"path":"navigation"},{"path":"environment.wind"},{"path":"environment.depth"}]}
connection.send(sub);
};

@rob42 reported that the assumption that Signal K ws is available on the same server + port where the sailgauge app was loaded from is not valid - the ws may be someplace else and one should be able to specify where to connect to.

Signal K raw data is in SI units and for example people often prefer SOG in knots, not meters per second.

Sailgauge should provide the option to choose units for the values displayed.

Installation doesn't work, reported by @rob42

I'm experimenting with sailgauge as distributed with the openplotter project for rpi. I assume the figure in the middle of the gauge represents SOG? In my case this figure appears to be representing the boat speed in meters/second instead of Knots! For example: if the boat speed is 5.22 Kn the sailgauge shows 2.7. What am I doing wrong?