In addition to upgrading components, the owners replaced the existing cables with heavier- gauge wiring to ensure the system can handle the loads.

conditioning units, the watermaker, and charge the batteries.

If we need more power, we can parallel in the start alternator and have 9kW available. This is useful if we have a generator failure, but there are times when it’s nice to be able to charge the batteries at 300A and still be able to run the watermaker or air conditioning.

To make it easy to parallel in the start alternator when needed, we mounted a switch and warning light on the dash that closes a 200A continuous duty relay to make the second alternator available to supply the load when needed by just flipping a switch.

With these four sets of new components and changes installed, we can solve all the problems we outlined above by combining these components in different ways. Repeating the requirements we’ll see how each is solved.

list above,

so it’s hard to justify giving up the space for a second generator in a small boat. If we do end up needing the backup, the hours on our main will go up marginally, but the trip will be saved. It’s nice to not give up space for a second generator and yet still have the redundancy protection that comes from one.

Efficient, light 240V loads: There are times when you’d like to run the oven for just 10 minutes, but it’s just not worth starting the generator for such a short period. The 240V inverter is happy to deliver the power and although the battery draw is high, it’s short enough that it doesn’t really consume that much power. It’s an efficient way to deliver the power for short periods without having to start the generator. Another usage model is low loads when under way. A single air conditioning unit draws less than 8A. It’s not worth having the generator on 24/7 and having to change the oil every 10 days if you only need a small amount of power. The combination of the 6kW 240V inverter and the large on-engine alternators allows even fairly large 240V loads to be run any time without needing to start the generator.

The combination of installing a 240V inverter, upgraded ship’s service selector switch, and a new charger service selector switch, allows the boat to be run entirely on the 60Hz inverter, while dual redundant 100A at 24V Mastervolt ChargeMaster 24/100s charge the batteries.

The Mastervolt chargers will run happily on either 50- or 60-cycle, so the batteries stay fully charged even on 50-cycle power while the boat continues to operate at full capability as a 60Hz system. We never need to start the generator to use the oven or laundry, for example. The combination of the chargers and the inverter can run any appliance at any time.

SHOREPOWER SHORTFALL

Very low amperage shorepower invariant: Extending on the 50Hz/60Hz invariant point above, we can run on shorepower connections as low as 10A at 240V or 15A at 110V even though our peak draw is often nearing 30A at 240V. Because the shorepower is charging the batteries and the inverter is powering the house, instead of needing the shorepower to provide the peak power requirements of the boat, we only need the average requirements. Often, for example, when a hair dryer is turned on and, say, the water heater is already on, the additional 8A draw will cause the shorepower breaker to disengage. This is because the shorepower is insufficient to meet the peak requirements of the boat.

If running using the battery charger and inverter pairing, as little as 10A is enough to power the boat even though our draws are often approaching 30A. Shorepower only needs to supply average

“We’ve been AYB customers for over 10 years. They’ve maintained the Patricia K continuously over that period, plus we’ve stored her there in covered freshwater storage during winter and summer months. They are extremely customer friendly and they have especially competent long-term employees that meet schedules and are always ready to give expert advice. And, as a bonus, their facilities and location are outstanding!

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