Isolated 5 and 3.3 Volt Power supply
he Raspberry Pi and most of the sensors need a 5 Volt power supply. In a yacht only 12V (24 maybe) is available. There are USB power supplies that run out of 12 Volt but a single high amp power supply should be installed. The one on the picture to the right show one option.
I have not tested any of them as I still run prototypes at home running of 220 V AC. The 3.3V needed for some sensors might be fed from the RPi, but 5 to 3.3 V converters are also available. Below is an example of a converter from 12 or 5V (any applicable really) to 3.3 V. However, this has common 0V and provide no galvanic isolation and should not be used to provide power to any unit connected to the computer system.
These power converters are very cost effective when ordered directly from China.