Exturnaroundman

A 38hp Isuzu may be somewhat underpowered for a 70ft boat (talking about a modern type engine, not an old fashioned high torque low revving type engine). Particularly if you intend to cruise rivers.

Never had a 12v fridge, had a 240v one which was used summer only, and the solars fed that easily. In winter store food in sealed boxes in the bow/cratch. As another poster said, buy the cheapest batteries and accept they have a certain life span, don't get too het up about equalisation charge and the like, just learn what works best for you. Expect to be shot down in flames ! No wonder we gave it up !

7 year old batteries will be well past their best. The op has had them for 9 months only, so probably doesn't know how well they have been looked after. New ones, start from scratch. Sorry only lived aboard for 12 years, no generator, no plug in, solar panels yes, led lights yes, would only have to run the engine for 2 hours a day in winter. Battery life 4-5 years.

If the batteries are 7 years old, this may answer your question ? Rather than spend money on a generator, new batteries might solve your problems.

You could try asking Bob Knowles Plant Services in Leicester, they still do spares for Enfield z drives so maybe able to advise. Google will give you the contact details.

A pair of binoculars can be handy for aerial spotting in rural areas.

The point I was making was that it is dangerous, regardless of the correct term. As you say room air is being burnt without fresh air drawn in from the outside, and the "flue" gasses vent into the cabin. Same with cookers of course, which is why lighting a few rings to take the chill off is not really a good idea, but we've probably all done it !

A portable gas heater ie superser would be an open flued device. Highly dangerous in the confines of a narrowboat, ventilation, carbon monoxide etc. Even if the heater was plumbed in, which wouldn't be allowed under current boat safety regs.

One worrying point to note in the advert is that it has a portable 3 bar butane heater inside the boat, presumably with a gas bottle inside the boat. Totally against boat safety regs, and a potential bomb. I wouldn't just be walking away, I'd be running a mile.

After reading all the posts on this topic, the OP still seems to think this will work. Can I suggest to the OP that he gets a seasonal job with a hire fleet, then he may see it isn't all roses. And as for hiring 50 wks a year, as others have said you have stoppages. Also dark cold winter nights will keen more battery and heating issues. Find out how many weeks the big firms use as their break even point, it'll be higher than you think.

As a long time lurker,ex live aboard and having spent several years working for hire fleets, I hope the OP doesn't mind a few extra comments to those already posted. As well as the enhanced bsc you need a landlords cert for the gas yearly. This has to be done by a gas safe engineer certified to work on LPG for boats (caravan and house cert doesn't count). As others have mentioned you need spares, and lots of them, if it can break, it will. Interior, at least 3 sets of bedding, ideally 4, to cover short breaks. Spare mattress(s) for little poppets accidents. Lots of wine glasses, crockery to cover all the breakages. Spare tv, radio, booster, light bulbs, water pump etc. Toilets, go for dump thru, but have all spare parts, if macerator have spare pan and control panel. Engine wise, full set of batteries, alternators, starter motor, gearbox, drive plate, control cables, all filters. Heating, if diesel a complete eberspacher/webasto/bikini replacement unit (so you can then get the one you took out repaired). Gas heating is a no no unless you are gas safe qualified to repair it. Boat hiring is a costly business to be in. As others have said, boat sponsorship, or buying into an existing business that has the infrastructure may be worth looking into.