it is navionics app. allows user to shade areas based in depth, plot, speed, etc. and adjust water level to actual so it is accurate.
the control is my GSA controls(gosurfassist). it was added by the original owner.
Tricky lake with shallow areas and not marked well. Lake level varies often with drought and then big rains. GPS helps my wife know where to go when I’m not driving too.
i had a 1998 boss 190 and never had a manual. you can find the pcm engine manual. it is about all i had. had the perfect pass manual. what are you trying to figure out ?