I have run a 12V solar powered system in my boat since about 2004. My 28' sailboat is set up to be able to live at anchor with no power connection. There is a 30W solar panel, a charge controller and two deep discharge marine batteries, the type usually used for electric trolling motors.
With this small of a system, the key is efficiency, since it is usually cheaper to be efficient than to add battery and PV capacity. I have no fridge, no pressure water. I avoid using fans, but do have them on board. The most used lights such as anchor light and cabin reading light are LEDs.
The system powers cabin lights, navigation lights, navigation instruments (depth sounder and knot log), music, vhf communications, autopilot (a power hog), electric bilge pump (it never runs, replaced with a hand pump), charging of cell phones and portable radio, charging of a handheld vacuum cleaner, and a portable inverter used for hand power tools.
30W of solar panels is quite low, usually sailboats will have more like 200W of PV panels. By avoiding heavy loads such as refrigeration and anything that produces heat or has an electric motor, you can keep your power needs very low.
I have this controller, which would allow me to increase PV capacity if needed.
SunSaver 10 amp solar charge controller with LVD
This cheaper controller would work on anything less than a 80W panel:
SunGuard 4.5 amp solar charge controller