Normally yes, but with Integrel it's up to you! The 'Charger' part of the Inverter/Charger is used to charge the battery bank (via shore power) which is typically a good idea while plugged into shore power.
The 'Inverter' converts 48V DC power from the battery bank to 110/220V AC mains power (or passes main power through to the boat when plugged into shore power). If you are planning to use mains power on the boat while at a marina, then it's convenient to plugh into shore power and turn the inverter/charger on.
However, since Integrel provides charges batteries so rapidly, it's not always necessary to plug into shore power if you can't get access, or the cost is too high while at a marina - with Integrel you have options - to plug or not to plug, it's up to you!