Power afloat.

[Guest]

I am considering the options for onboard power on a 42' cruising yacht. Generator was the first thought but cost / convenience questions prompted re-examination and the possibility of Big Alternator (200A), Big Battery Bank (4-500AH), and smart invertor/charger was raised. This would mean modifications to the main engine but should give reasonable independence should shore power not be available without frequent main engine usage as the storage capacity available should give a full day's power requirements between one hour charging cycles.
Does anyone out there have any experience of a similar set-up or opinions on the suitability of same.

Thanks

 

[Guest]

I prefer the generator option

Your plan equates to many additional hours of engine running without doing any more than tunring an alternator. As engines require substantial maiuntenance in comparison to generators, and diesels are ruined by running under no load, I think a genset is the best option.

Otherwise, why not invest in a wind turbine and solar panels to supplement your engine? 500 Ah of battery is a lot of weight - what on earth are you running?

 

[charles_reed]

You seem to be proposing solutions without analysing the problem.

Unless you propose to cook by electricity, your outline is way over the top, especially on a relatively small boat, like a 42'.

Suggest:-

1. You work out your maximum under-way and anchored 24-hour consumptions. As a guide, a 40l fridge needs about 45 ah in 30C ambient, an electric autopilot working hard consumes about 4.5 amps/hr, tricolour about 18ah every 24 hrs, domestic lighting/waterpump about 12 ah etc etc.
2. Your battery capacity should be 3 days of underway or 5 days of anchor (both these are on the generous side).
3. Then add in both wind-generator and and solar panel say 4 amps from your generator and 180 watts from a solar panel array.
4. Upgrade your alternator - mine is 90 amp compared to the standard 35 amp - your wiring to carry 200 amps will need to be massive. Furthermore the power-curve of the alternator is very important - it's great for bar-boasting to claim 200 amps at 4000 rpm - but that's useless when your motor is normally turning over @ 1600 rpm.
5. Put in a smart regulator like the Adverc or TWC, so your alternator will recharge your 24-usage with 60 minutes of running.
6. Get a pulse charger - for when you're on shorepower. A 15-amp charger is plenty for 300 amp-hours of battery, more if your battery bank is larger. To large a charger not only trips your shorepower line but also causes too much gassing.

The Blue Water Cruising magazine had a series of articles on shorepower - if you can get a back copy of that you'll also get some reasonably sensible wiring diagrams.

With a big alternator and a smart regulator, your engine will never be working under no-load conditions, to put your mind at rest - in fact your big problem, if you have a large alternator, is getting enough prop-power, on start-up, to pull the skin off a rice pudding.

A separate genset makes sense for a big boat with electric winches, aircon, freezers, microwave, TV etc, but you're talking of >60'.

Mind you I met a mad Deutsche in Ribasdella who had a separate genset, but that was for welding more pieces onto his boat.

 

[jamesjermain]

I agree with Charles that you are overdoing the alternator at 200amps but, since most of us think of a 42 footer as quite a large boat with a lot of electical kit and high consumption, I also like the idea of a small independent generator. Not only does it mean you retain electrical power in the event of an engine or alternator failure, it also means that, at anchor or in a marina, you can run the ecomonical, quiet and efficient generator rather than the costly, inefficient engine which will be suffering damage due to being underloaded.

But, before you go to the expense of either option, I would do some careful sums on electrical consumption and then examine how much of your usage could be covered by a wind generator and/or solar panels.

JJ

 

[Guest]

I'm also considering the options for a similar size boat. Have you heard of the Whispergen diesel generator (external combustion based on sterling engine). If you can afford it and can be convinced of its long-term reliability I think it is the ultimate solution. When considering its cost (over £7,000) you should take into account what you will save on - solar panels (and in my case the goal posts to mount them on, wind generator (noisy anyway) and extra large alternator and smr charging. You could also get away with fewer batteries. Have a look at the details at onboardpower.com.

Last month's Yachting World contained one of their surveys of ARC participants' experiences of equipment reliability. Diesel gensets seem to be virtually standard for ARC boats over 40' but conventional internal combustion sets are notoriously unreliable. I have ruled this option out because of this and the noise. The survey did mention the Whispergen but only briefly (and not favourably).

I know it is possible to manage with a large battery bank, big alternator (with smart charging etc) solar panels and wind/water generator, but wouldn't a Whispergen be wonderful (if it worked as promised).

 

[Guest]

Aquagen

If you're thinking about solar cells and wind generators as the solution, don't forget to look at Aquagen (towing generator), especially if your concerned about power for longer passages. About the same price as a good wind generator, it has an impressive output for a very small loss in boat speed. For a bit more money you can add the kit to convert it to a decent wind generator while you're in port. Probably the lowest cost per watt solution.

 

[Guest]

Re: genset and no gas

The battery bank won't be able to power heavier load items. And gas causes lots of accidents. I use a genset, shorepower when available, and no gas.