230v battery chargers can be integrated into the boats electrical system.
Utilising either shore power or power from a high alternating current (AC) engine driven alternator, they come in a range of shapes and sizes.
Buy chargers that are rated for the marine market. They will have crud and moisture resistant cases and be specifically developed for our demanding conditions.
If buying the smaller lozenge shaped units, make sure you buy the correct size for your battery bank. For example chargers rated at 5 amps are suitable for batteries ranging up to about 120 amps only. It may be better to bite the bullet and go for a unit rated at 10amps or even 25amps. Charge times will be faster and battery banks will be better maintained.
Sophisticated canal boat power management systems use combination inverter/charger
units for a one box solution to power management.