An inverter turns 12 or 24 volt battery power into mains. The question is never really whether it will run an appliance, it is whether your battery bank and cabling can supply the current for as long as you want to use it.
A three minute kettle boil is a genuinely large withdrawal from a modest bank. Understanding that up front is the difference between a useful installation and a disappointed one.
Inverters are rated for continuous output and for a short surge. Motors, compressors and power tools draw several times their running current at start up, so the surge rating decides whether things actually start.
Resistive loads, kettles, toasters, hair dryers and heaters, do not surge but they are simply large, and they are large for as long as they are on.
Every mains watt has to come out of the bank at battery voltage, so currents are high. That drives heavy, short cable runs, correct fusing right at the battery and terminations that can handle it.
This is also where lithium changes the answer. Lithium banks can deliver high current without the voltage collapse that makes lead acid struggle with inverter loads.
A plain inverter is the simplest option. A combined inverter charger also charges from shore power and can transfer between sources automatically, which suits boats that alternate between marina and anchor.
Anything that connects the inverter output to the boat's fixed mains sockets involves the AC installation, earthing and neutral arrangements, and is qualified work.
Coffee machines, microwaves and induction hobs are all possible with enough bank and enough charging. On a boat with a modest bank and engine only charging, gas or a low draw alternative is usually the better answer, and we will say so.
A large inverter will, but a kettle takes a serious bite out of the bank each time. It is realistic on a decent lithium system with good charging, and marginal on a small lead acid bank.
Only for very small loads. Anything meaningful needs its own heavy, fused feed direct from the battery, because that socket and its wiring cannot carry the current.
Yes, most draw a small standby current, which adds up over a week on a mooring. Switching it off when unused is worth doing.
We size inverters and banks together, install the DC side safely and sort the AC connection properly.