I use an 80 a/h leisure battery ( £35- 40) with a £15 solar charger which
just about stops the natural discharge of the battery. It then requires
charging only about twice a year when the voltage falls to below 12v.

TonyB

As I normally daysail I do not need a battery in my boat. But when I
occasionally cruise for a few days, I would like one, but only for the
lights. I do not have other power consuming devices in my boat.