Originally Posted by Shifty
the furnace draws about 6A when it's running. We tend to spend more time on the dock plugged in when it's cold anyway, so it hasn't been a major contributor to draw. I did a full spreadsheet for draw based on real numbers puled from my battery monitor on the current boat. We also have hundreds of hours aboard, so we have solid intuitions about power use.
For the new boat, we're using estimates and assumptions. The fridge is a small domestic model, which runs on AC only, so the inverter will be on all the time. There are a number of items that will be more power intensive. But, with a quieter generator (running our current generator is a bit loud) and the solar panels, I suspect our usage patterns will be different.
From the input on this thread, it sounds like 300 Ah useable should be fine if we plan to run the generator or cruise somewhere every day. If we wind up falling a bit short, we can always add another 200Ah battery.
If you are concerned about it, you can always ask Trevor about adding another battery. Likely it would be cheaper and easier to have them do it at the factory than waiting until after delivery.
Another thing I have thought of repeatedly is the possibility of combining the house and thruster banks. Iím not sure how the NP45 is configured, but that would give you an 800Ah bank to use for both. It might be worth considering and asking Trevor and a qualified marine electrician.