I'm still collecting ideas and thoughts for my next boat, if there ever is one, which will definitely be custom built. I started a thread about it last year which I can't find.
I was reading Noelex's classified ad for his old boat, and among many other excellent features, really liked his generator
. It's a standard boat propulsion engine
-- so already marinized with standard parts
-- a huge plus for serviceability and parts
availability -- driving a standard heavy duty alternator
-- ditto. This is similar to some home-made DC generators we've seen on here, except that instead of a home-made marinization of an undersized Kubota, this just uses a standard propulsion engine
from a much smaller boat.
For a long-distance high latitude adventure cruising boat, I think this is just the ticket -- the ultimate in robustness, serviceability, and simplicity.
I am not a fanboy of DC generators because I don't see any overwhelming advantage in efficiency. Now that we have modern charger/inverters which make a seamless conversion between DC and AC and back, I don't think we really care whether power comes to us in DC or AC form. I like heavy duty low speed AC generators and have had excellent service
from my Kohler EFOZ6.5 and would not trade
it for a homemade DC generator
with a home-marinized Kubota, but something like Noelex's generator is something very different.
I think on my next boat I'll have something like that. I would use a Beta or Nanni, the smallest 3-cylinder propulsion engine they make. I would have a flywheel and jackshaft in place of the gearbox
running two large frame Leece-Neville 36 volt or 48 volt alternators through short toothed belts. That will give a capacity of up to 6 or 7kW with both running, but by varying the engine speed and using one rather than both alternators, the output can be regulated.
I would have a third identical 36 or 48 volt alternator
on the main engine. This gives great flexibility and redundancy in power generation, and one spares kit will cover all three alternators.
This power will charge a 36v or 48v battery
bank, maybe LiFePo, which can absorb high charge rates, using this generator to its best advantage and allowing for short generator runs.
Having this kind of power on board eliminates the question of how to power the windlass
, bow thruster, and furling gear
The DC bank will produce AC power through ganged charger-inverters, maybe three like the Victron Multiplus I have now. This is not an ideally reliable unit, but in a gang of three the built-in redundancy will compensate. Like that there will be about 7.5kW of available AC power.
DC consumers powered through 24v or 12v droppers. Probably there will be one large 24v dropper powering a separate 24v bus.
To make the generator perfectly serviceable, I guess is should live above the main engine and under the cockpit
sole. If this is bolted in place and easily removeable, or with a large opening hatch
, then access should be ideal.
Everything needed to make the generator run, including its start battery
, should be located right there in the same place and should be separated as much as possible from other systems.
Such a generator makes it easy to take off mechanical power for other purposes, but I think there's hardly any point to a mechanically driven watermaker
pump or bilge pump
, since you have nearly unlimited electrical
power for this. Maybe a large mechanical bilge pump
would make sense just for the case of some disaster which has knocked out power, but you can still start the generator since its start battery is separate and well above the waterline.