DetroiTug's Tug is going together

[fredrosse]

Keep in mind that #35 chain is not roller chain, and will develop high friction if lubrication is not kept after. There were tests made long ago for go-karts (more severe service, with more dust than found on a boat), and #35 chain drive would sometimes eat more than 30% of the power produced by the go-kart engine. Roller chain (#40, #41, etc.) had efficiency in the 90% or higher range. Of course, motorcycle "O-Ring" chain drive would be best, although somewhat expensive.

[barts]

I do keep things pretty well lubricated. How much power does my displacement pump require? Well, at 350 rpm I'm pumping 350/1800 * 1.5 gpm = .291 gpm. At a typical 150 psi, that means .025 hp in work done... so overall, the pump uses a tiny fraction of the engine power.

If you're looking for a more efficient charging method, consider a permanent magnet motor. You'll need a circuit to control the charging voltage, but this is quite doable.

- Bart

[DetroiTug]

Bart,

I'm reading up on DC motors and charge controllers right now. Looks as though a quick and dirty method is just connect the motor directly to the battery and put a silicon diode on the positive lead, for under 12 volt output. But there is the possibility of overcharging the battery. There a re a few "charge controllers" available.

Fred, Yep, appears an auto type alternator is not much good at below a few thousand RPM, very inefficient.

There should be ten commandments for the steam hobby, and one of those should be: Thou shalt not use automotive parts They belong on cars not on steam engines.

-Ron

[barts]

Bart,

I'm reading up on DC motors and charge controllers right now. Looks as though a quick and dirty method is just connect the motor directly to the battery and put a silicon diode on the positive lead, for under 12 volt output. But there is the possibility of overcharging the battery. There a re a few "charge controllers" available.

-Ron

I did this 30 years ago on a 6 HP Briggs in an old dirt bike frame I'd converted to a street bike... a small DC motor driven by a small sewing machine belt... and a diode isolator. Worked fine, but it was a small motor and the headlight was always on.

A wind PWM charge controller would do a fine job and are commercially available. A quality DC surplus motor would make for a pretty good charger... and with appropriate wiring could be used to bump the engine over TDC. You'll still want a diode to block reverse voltage from the controller when going astern.

- Bart

[Lopez Mike]

Fred,

That is interesting that you have run into #35 chain that isn't roller chain. The odd bits I have around the shop are all very much roller chain. They come apart just like my bigger (like #50) chains with rollers turning on pins and all that stuff.

Now you've got me all paranoid. I'll have to check to make sure any future purchases are, indeed, roller chain. I hadn't known to watch out for that.

I love chain in many applications. But in my boat I'm going to change to a V-belt, a toothed timing belt or a serpentine type with multiple grooves.

I've had extremely good experiences with the segmented V-belts that you can take apart and change the length. I buy them from Grizzly Industrial. I have them on my drill press and on my 16" metal cutting band saw with variable speed drive and a one h.p. motor. Smooth and reliable. If needed, they can be threaded around a prop shaft for a rear engine drive of an alternator or a pump.

[DetroiTug]

Mike,

It must be the grade of #35 roller chain, I just checked this one and it doesn't have rollers. It's ANSI grade "roller" chain from McMaster-Carr. However, using a large sprocket on driver and driven shafts, it's probably not that big of an issue. Now on a small Comet type power sports clutch they use very small sprockets that would require the links to pivot much further on each pass. If the chain was dry/binding, that would result in high losses in the transmission of power.

-Ron

[DetroiTug]

Fred,

Thanks for re-posting the alternator specs. If my research is correct, this in the same alternator Yanmar uses with a different case. Kubota uses them too. This particular model is used on Toyota forklifts. The horsepower requirement is based on 50 amps output. I'm really only looking to get 5-10 amps output, same as a small battery charger running throughout the day and then I can run the spotlight at night, run water pumps etc, and then charge while running and back up fully the next run. For 2-3 day river trips. Spinning the alternator at 2000 RPM, it puts out 7 amps, but that has to do with the condition of the battery I would think.

-Ron

[barts]

I have a small (50A) one-wire alternator from a Metro on my Burning Man mutant vehicle, which has a 6 hp Briggs & Stratton. It's belted to run at 3.5 x engine speed. I've had to install a 1 ohm power resistor in series (with a switch to short it) to start the engine; even at manual recoil speed this thing places enough load on the engine that I cannot start it if the battery is low. Once the engine is running, I close the switch and the engine loads down until the battery is replenished.

The gain on such units is quite high so that cars recharge their batteries quickly when driven for short trips only.

Discharge that battery some and you'll likely see a big jump in amperage; mine does 15 -20 A very quickly.

- Bart

[DetroiTug]

I shelved the alternator for another project - I/C related application.

Ran all sorts of tests, totally bypassed the regulator and ran 12 VDC straight to the brushes, and no output. It needed 2000 RPM and even then the amperage output was very low. And too, the field required quite a bit of current. This particular Nippondenso alternator was designed to run at high RPM's apparently - in the 3-4000 range. In short, no good for a slow turning steam engine unless it is geared up, way up. Full fielding the rotor, each of the stators three legs put out about 3.5 volts AC @ 1300 RPM. Not enough to exceed the 12.8 volts DC required to start producing any current to the battery.

Kubota uses a small PMA alternator and I almost bought one, however it is rated to put out 14 amps, and that is probably in the 3-4000 RPM range. Again not much at the RPM's I'm belted for.

There are probably some other alternators that will work in slower applications, but I've taken the exploration as far as I want.

Instead, settled on using a 60 volt/4000 RPM NEMA 23 Servo motor, essentially a brushed DC motor with more poles than a standard motor. It's 60mm in diameter and about five inches long, will be easy to mount. Puts out a nice steady 7amps at the engines cruise RPM. Using one side of a 25 amp 250 V full wave bridge for the diode in the positive lead, to keep the battery from trying to feed the servo and spin it. Should work really well. Will mount a voltmeter and ammeter to monitor the battery and a toggle switch to turn it off and on when needed.

The kicker, everything I wound up using, I had here already..

-Ron

[DetroiTug]

Finally building windows and doors. I've been so busy with regular work, haven't had much time to work on the Tug.

Here is the Port door, it's two sections and will be removable. The Starboard is done and just needs to be fitted to the opening. Have to make the lift off hinges, can't find the exact type I need. These doors will hinge from the front to the inside of the wheelhouse, then they will hook either side of the wheel. I figured that would be easier than trying to remove them, if I want them open. They would get pretty beat up taking them in and out. If it's 90 degrees, I'll take them out completely, otherwise just hook them open. Mahogany with marine Okoume panels. Have the two aft cabin doors made too, just need to be varnished and hung. Have the 3/16" Lexan for all the windows now too.



-Ron