Unless it will only be used while plugged into 110 shore power at the slip. If you will be using the charger while cruising and will charge from an on board generator it's not enough. A 460 amp bank that is half discharged will accept a lot more than 40 amps for about the first 45 minutes. If you're going to be using a generator to charge you want to run that generator as little as possible using a charger that will give the 460 amp bank everything it will accept for as long as it will accept it.

My feeling is, if you'll be charging in the slip from shore power the 40 will be easily enough. If you 'll be charging from a generator at times get a bigger one. or,,, I'd think about a 2,000 charger/invertor. They don't cost much more than a stand alone charger and usually include about a 100 amp charger,, and,, an invertor is always a desirable piece of equipment to have if you cruise at all.