The gas-fired boiler between the en-suit toilet and the bathroom,
can be used to heat the water for baths/showers, though it is rarely
necessary to do this, as a few hours cruising will normally give an
adequate supply of hot water.
The boiler is useful though, for warming the boat when it's not cold
enough to justify the solid-fuel stove, but cool enough to need a bit
of warmth. Each radiator has its own tap, so it isn't necessary to
waste heat at an end of the boat that isn't being used.
Being flexible, it can be used to just warm the bedroom for instance,
when the solid-fuel stove is warming the rest of the boat.