Electrical system for boat

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TriangleTom
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Electrical system for boat

Post by TriangleTom » Sat Aug 17, 2019 10:13 pm

For those of you who have an electrical system, what are you using to charge it and how much battery capacity do you run? An automotive alternator seems like an option, but given the low speed and reversing nature of our engines, is this workable?
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Re: Electrical system for boat

Post by barts » Sun Aug 18, 2019 1:54 am

If you have a rigid canopy, solar panels make a lot of sense if your climate isn't too sunless. A couple of 100w panels and you're set. Large boats fit alternators, but I've seen those only on 35-40 footers.

Most small boats just pack enough battery to last a weekend.

Rainbow, our 26' ex-Navy whaleboat, is getting a coupe of panels. Otter, our smaller river launch has a battery which runs a fuel pump and LED nav lights, has no charging system.

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Re: Electrical system for boat

Post by RGSP » Sun Aug 18, 2019 8:41 am

TriangleTom wrote:
Sat Aug 17, 2019 10:13 pm
For those of you who have an electrical system, what are you using to charge it and how much battery capacity do you run? An automotive alternator seems like an option, but given the low speed and reversing nature of our engines, is this workable?
As a good rule of thumb, electrical generators work more effectively at high-ish speeds, but they can have windings arranged to provide the correct voltage at lower speeds, although the output will be moderate. Alternators designed for things like dump trucks or agricultural tractors are often designed for low speed use, and are easy enough to source.

Another way of doing things is to use a permanent magnet DC motor instead of a designated generator. That can work very well, but I suggest you find someone to help with selecting the right motor, and the possible variations are considerable. Alternators most often work just as well in either direction, but a DC motor will require a bridge rectifier to cope with the reversing main engine: this is cheap and easy to arrange.

As mentioned above, solar panels are good, because although the output is lowish, the boat is almost certainly sitting doing nothing for 98% of its life.

A final thing to mention is small petrol engined invertor generators: they are small and light things, and these days not expensive. I can't speak for all brands, but at least some of the Chinese sourced ones are ridiculously cheap and work reliably for very long periods. Other Chinese ones are no doubt dreadful, so be careful if you go that way, but good ones do exist!
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Re: Electrical system for boat

Post by DetroiTug » Sun Aug 18, 2019 2:34 pm

A generator on a small steam engine is very simple. I use a Nema 23 90 VDC brushed servo motor which is just a DC motor. Belt it at around 1200 RPM and puts out about 6 amps. I use one corner of a 600V/25A Bridge rectifier ($2) as a diode to prevent the voltage coming back at rest and low RPM. Very cheap and simple to set up. I found some antique gauges to monitor voltage for battery condition and amperage output.

I tried riding lawn mower generators and small car alternators etc etc. None of them worked as good as this set up I have now. The problem is the RPM, most are set up to work at thousands of RPM which we don't have. The permanent magnet Windmill generators would work too, but probably more than we need. Again, it is a limitation of our plants, loss of one horsepower in noticeable, so a higher amperage charging system is going to be a larger negative to shaft horsepower under way. In other words, keep it under 10 amps output at cruising RPM, lest it become a situation where charging the battery is intolerable due to the considerable loss of hull speed.

The solar panels are a better option, but the generator is a better discussion piece. The generator is better if battery power is needed more quickly. The way it's used, If needed, use a battery charger dockside and then if I'm out for a few days or simply away from shorepower, then there is a switch that can be thrown which completes the charging circuit when needed to top off the battery, I run mostly without it. I have a very large deep cycle marine battery with a lot of capacity.

Met up with Scott from the forum here on Friday for a run on the Tug out on Lake Saint Clair, we had a good time.

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Re: Electrical system for boat

Post by barts » Tue Aug 20, 2019 6:45 am

If you're interested in more of a period piece, there are various articles on the net about making slow speed generators for wind turbine use. These could support direct drive from our steam engines; some skill w/ electronics would be needed to properly regulate the output, but this could look very much like an old open frame generator.

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Re: Electrical system for boat

Post by Lopez Mike » Tue Aug 20, 2019 4:11 pm

I second the advice to try to use solar when possible.

I don't have a canopy and might not for quite a while. I do have more immediate thoughts to buy a 12v oil burner for which I will need some current. I have a friend with a Stuart Sirius and if I can talk him out of it I would buy a largish stepper motor and rectify the output. These modern motors have wonderfully strong magnets and the Sirius is designed to run at fairly high speeds.

There are tradeoffs no matter how you do it.
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Re: Electrical system for boat

Post by DetroiTug » Tue Aug 20, 2019 6:21 pm

Lopez Mike wrote:
Tue Aug 20, 2019 4:11 pm
There are tradeoffs no matter how you do it.
That should be the motto for this whole hobby. Very rarely does a gain result in zero cost.

Did you get that economizer on there yet? :lol: (running joke)

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Re: Electrical system for boat

Post by DetroiTug » Tue Aug 20, 2019 6:36 pm

Lopez Mike wrote:
Tue Aug 20, 2019 4:11 pm
thoughts to buy a 12v oil burner for which I will need some current.
Those Beckett style gun burners draw a lot of juice, I know guys that run them on steam cars and I do not know of one that has a charging system that can regenerate the power required to run the burner and still propel itself. It may be possible, I haven't seen one though. The Doble steamer used an electric gun burner, but it was a very high output plant, i.e. main burner about 1.2 million BTU. Our little woodfired plants are probably around 150k BTU. Forced draft etc.

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Re: Electrical system for boat

Post by Lopez Mike » Wed Aug 21, 2019 1:28 am

I just sent Beckman an email asking how many amps it draws. Somewhere I got the impression that it was around five amps.

Just spent an hour getting a 1.5 inch pipe nipple loose. The dolt who assembled the power plant used a schedule 40 one and by the time I had it in my hand it looked like nothing in this world.

Our association rules require schedule 80 from the boiler to the first shutoff/isolation valve. I'm wondering if bronze stuff would do the trick. And would be as strong and wouldn't have any electrical tricks to pull on me. Or even stainless though I'm suspicious about oxygen starvation and such.

One of my steel 1/2 inch schedule 80 nipples from the boiler to the main steam valve ("Main stimp wowve!) was eroded on the outside to the depth of the threads after five years of damp, heat and neglect. Maybe I'll try painting the replacement pipes though barbecue paint isn't that resistant to corrosion. Maybe there's something better? Something I could brush on?
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Re: Electrical system for boat

Post by barts » Wed Aug 21, 2019 5:51 am

To make boiler nipples removable, use neverseize. There's one w/ PFTE specifically called out for steam piping.
Teflon tape works as well, but the goop is better. RectorSeal #5 is similar - I've had no troubles removing boiler nipples after 10 years.

To prevent corrosion, paint fittings with moisture cured polyurethane I like Aluthane ( https://www.epoxyproducts.com//aluthane.html ) but the web page reads like a Dr Bronners soap bottle. Good for 400F and sticks like anything. POR-15 would work as well, but that's more expensive due to all their advertising.

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