Modern electronics move and change faster than any other equipment on a boat. My 18 year old boat is on its 3rd Chartplotter, 2nd VHF radio, and 3rd Stereo. The sailing instruments are original and still working but will need replacement soon.
These days, even quite small boats can have extensive instrumentation.
Chartplotters or MFDs (Multifunction Displays) are the most important instrument on most boats, from a 20-foot sport fisherman to an ocean going sailboat. Here a few that we recommend. Many of these feature a built in Fishfinder or Depth Sounder. All of them have GPS, and support maps available worldwide.