Matt, it really depends on how you plan to use your electrical system
, especially, how much AC gear
you have on board and how much you use it.
I live on board my boat four or five months a year, and sail a few thousand miles a year, and so I have set up my boat for comfortable living. My boat was built with washer/dryer (a Godsend) and microwave built in, and besides that I use various kitchen appliances
, coffee machine, electric
kettle, vacuum cleaner, power tools, etc. I also use AC power for charging a multitude of small electronic devices -- although most of my personal things (laptop, tablet, phones, etc.) are charged from hard-wired DC chargers, my boat sleeps seven, and when she's full of people, then every outlet on board is full of different chargers -- no way to avoid that.
So on my boat, we have a Victron Multiplus 3000/24/70 charger/inverter, which is switched on 24/7 so there's always AC power. As others have said, inverter power ratings are grossly overstated, so that a 3000 watt inverter is really not good for much more than 2000 watts continuous. But this has been enough for our uses. You have to be careful not to have too many large consumers on at once but this has not been a problem for us in practice.
Remember this also depends on batteries. It's no good to have a huge inverter if you don't have corresponding battery
capacity. We have 420 amp/hours (nominal) at 24v, equivalent to 840 at 12. More is always better, but I really don't feel too limited by this. It helps on our boat that we have an almost silent, heavy duty diesel generator
, so it's not burdensome to recharge a couple of times a day if necessary. If we didn't have a painless way to recharge, we might be less satisfied with the battery
One feature you should insist on in any charger/inverter is power boost -- I believe Victron and Mastervolt have this -- not sure which others. This is incredibly useful. If you are on shore power
(or generator power) and there is more demand for electrical
power than shore power can deliver (you set the limit yourself on the control panel), then the charger/inverter will supplement shore power (or generator power) with inverted power from the batteries. For short term loads like motor
startup (like a vacuum cleaner or power tools) or electric
kettle, etc., it's absolutely brilliant -- otherwise you'd have flipped breakers or blown fuses
, or you have to shut down everything else on the boat, etc. Just incredibly useful.
If you won't have anything like microwave, kettle, coffee maker, etc., then you might not need as much as 3000 watts (very nominal). But there may not be any point in downsizing since the inverter capacity is linked to charger capacity. Our unit gives 70 amps at 24v, which is only 16% of C -- wouldn't want a smaller one for our size of battery bank.
As to which maker -- Victron is beautiful, expensive equipment
with superb functionality, but in my use (and that of many others) is disappointingly unreliable. Not sure I can recommend it wholeheartedly. Victron's main rival is Mastervolt, another Dutch company. Maybe there stuff is better; I don't know. Mastervolt stuff is much lighter, in any case, because they use switching-mode transformers instead of the big heavy magnetic transformers on Victron. That will make it much easier to install than Victron. Whether the magnet type is so much better, I don't know.
I agree with HopCar above about how nice Newmar gear
is. It's very expensive and pretty. My boat was originally built with all Newmar stuff, but the main battery charger blew up a few years ago at the age of about 10 (which I guess is a decent service
life for such a thing). I don't know whether they make charger/inverters with power boost, or not -- that is what you'll want in any case.
Good luck, and let us know how it turns out!