Two Evils - Please Help Me Decide

[anjou]

Im trying to decide on the best design option for live aboard electrical options.

Im planning on having a 4 cyl, 70hp main engine for propulsion and hot water via a calorifier, plus possible option of 2 x 24v alternators feeding an inverter/ batt bank to supply 2 ring mains round the hull, one being 12v and the other being 220v.

Only the washing machine, macerator, microwave, vacuum, hairdryer etc will be 220v, the rest being 12v, ie, engine room, galley, heads extractor fans, all lighting, tv, radio.

So, ........is it better to spend the money on a large bank of batts and large inverter, OR
go for a stand alone diesel genny, one for sale is 8kva, marinised in a sound box, and have a smaller inverter and not put such demand on the batts.

I anticipate most time will be spent moored and it doesnt make good sense to run a larger engine for a few hours per day just to charge batts (hot water is a by product). Diesel cost, bore glazing etc is downside for an engine which is well oversized for making some electric.

I could just run the jenny when washing and vacuuming needs doing and go for a smaller inverter to just run the microwave which needs @1200w and the toilet macerator @800w. Macerator will only run 15 seconds with each flush, maybe 5 mins with a shower.
Microwave only needed maybe 15 mins a day. The jenny can be set up to auto start on demand.

With the 8kva capacity, more than enough to run washing machine and heat calorifier via immersion element at the same time, OR, convert the heat exchanger to heat the calorifier.


Which is the lesser of these two evils?