Engine/transmision/alternator temperature in OpenCPN dashboard or a lightway display

[olewsaa]

I have a little box in the engine room sending temperatures of engine, transmission and alternator to the SignalK server via wifi,
my project of Internet of Things on Board IoToB.

This works nice and I can use a web browser (chrome or another with Javascript) to run the instrument panel. This works well
when not much else is running. If running OpenCPN 5.0.0 things grinds to a halt, possibly running out of both memory and available 
cores. I have tried some lightweight web browsers, but they don't support Javascript and hence cannot display the instrument panel.

A quickfix is to open the SignalK diagnostic window. This show the numbers nicely, but it's not the best solution.  My suggestion is to 
in some way convert the SignalK messages to NMEA sentences and with some magic get the dashboard of OpenCPN to display the temperatures. 
So far I have not really found how NMEA sentences for these engine (etc) look like. NMEA seem more geared towards navigation. 

Any other tricks could be of interest, a X11 application that just display some selected SignalK messages could also be nice. 

Ole