They're expensive to buy, noisy to run, awkward to store, and can even put your insurance at risk if you're keeping petrol on board outside a fuel-safe locker. So many boaters don't bother with generators. If you're hungry for power, though...
...first know that you can already draw up to about 300 watts - more if you have the engine running - either directly from your boat's 12-volt batteries or through an inverter, a gadget which converts your boat's DC battery power into a limited amount of 220-volt AC mains power. So, even without a generator you can easily use a phone charger, laptop, radio, hand-held kitchen blender, maybe a travel iron.
Also bear in mind that generators are one more thing to break down and, while you're waiting for that to happen, another thing to annoy your neighbours with.
So you do want one. Ok...
If you don't have access to a mains hookup on the bank and you want to hoover, straighten your hair, or practise your topiary on a nearby hedge, then you'll probably need a generator, but you'll want the right kind. Any neighbour will tell you that there are two kinds of generator: quite noisy and very noisy.
The most basic generator is often called just that: 'a generator'. Usually these are built around a metal frame with the engine exposed, because they're designed for building sites. Your neighbours won't be thanking you if you start up one of these on a sunny afternoon. If your budget doesn’t stretch too far you may be better keeping this for emergency use only and relying on your boat engine instead. These generators have also been known to damage some sensitive equipment like laptops. A mid-power version of these noise-makers will set you back about £400.
The other type is a 'suitcase generator', which is quieter, more portable, and better designed for everyday household use. It's built for boaters and caravanners and, being of better quality, can be used to power sensitive equipment. And of course it's more expensive, at about £800.