I have just bought a new boat off someone who only used it to cruise every summer. It has a 240v fridge on it, a 240v water pump and a webasto heating system. It has a good set of solar panels that charge up the batteries very quickly. So, when the sun is out, mid morning, I can run the heating no problem. However, with it not being summer - and there not being much sun right now - I find that if I put on the heating, (which requires the water pump to be on) when I get back from work and it's dark - it runs down the battery in no time at all and the heating goes off automatically. I am not bothered about the fridge, which just eats energy, so I switch that off. And I also don't watch TV. Its just the heating - that I would like in the evenings. I run the engine on tick over for a couple of hours but it doesn't help much at all. Would changing to a 12v water pump make a big difference and use much less energy, as I wouldn't have to put the inverter on?