The Steamboating Forum

Dear forum participants, my congratulations with Christmas Eve! I wish everyone to complete their projects !

Thank you.
And remain safe and healthy.
RussN

Merry Christmas everyone

My small locomotive boiler has tube diameters of 25mm and a boiler wall thickness just under 8mm. his seems to hold pressure quite well.

Fred? Ron? Anyone with some advice on this subject?

Mike

Dear PeteThePen, Lopez Mike, RNoe, TahoeSteam, DetroiTug and all forum members who supported me with their advices and kind attitude, I am glad to welcome you! For various reasons, the progress of my project slowed down a lot, but did not stop at all. In our "southern latitudes" the temperature on some days dropped to -16-18 degrees Celsius, at nights to -25 degrees Celsius. Snow fell as much as it usually happens in Siberia. But in my workshop, I continued making eccentrics. Here is a photo:

I would like to say a few words about the construction of eccentrics. The diameter of each is 120 mm. plus flange and overall diameter - 131 mm. Thickness -29.75 mm. Eccentric offset - 21.7 mm. The total travel of the eccentric is 43.4 mm. I would like to achieve full compliance with the design of eccentrics on steam engines of the late 19th century. I am attaching photos and drawings. I do not know if this design of eccentrics will be correct on my steam engine and how it will all work. On the forum, I have not seen detailed photos or drawings of eccentrics that are used on your steam engines. I hope for the recommendations and advice of the forum participants. Best regards, Ingvar.

Very good work as usual.

You had me puzzled for a minute boring an offset diameter in the three jaw chuck. Then I realized one jaw was skipped a tooth out on the scroll, very clever.

Ron

As a side note, these can be successfully made from bronze shaft. My steam car has them and they have serviced very well.

Made some rough numbers for your steamboat project:

Your compound engine, 3.9 in HP, 6.7 in LP, 5.2 in Stroke (100mm + 170mm x 132.5mm), running at 250 RPM, with 145 PSIG (10 Barg) Main Steam pressure, will produce about 12 horsepower, 9 Kilowatts shaft power.

The boiler needs to make about 260 Pounds per hour (120 kg per hour) Main Steam Flow, 145 PSIG (10 kg.cm2), and at full power will consume about 34 pounds per hour (15 kg per hour) of coal fuel, or about 2.7 US Gallons Fuel oil per hour (10 liters per hour). Watertube boiler heat transfer surface area should be about 40-50 square feet (4 square Meters).

This is a rather large steam launch engine, since a pure displacement hull is typical for this project, small powers drive a large boat. I have assumed a hull, and your actual hull can be different by significant amounts, so understand these are only rough numbers:

Hull Length 36 feet (11 Meters) Beam 7.5 feet (2.3 Meters) Draft 2.5 feet (0.75 Meters, Design Displacement, 10 tonns. This is large, you could select a hull about 70% of this size, and it would be satisfactory, and use much less power.

You can make 6.25 knots (11.6 kM/hr) with this configuration, driving a 36 inch diameter (0.9 Meter) propeller at 250 RPM. Propeller Pitch is 38 inches (0.95 Meter) Shaft Power is 11 Horsepower, (8.25 Kilowatts)


Considering a smaller boat, about 70% of the size described above, 25 ft/7.7Meter at 3.5 tonns displacement, you can make about 7.5knots (14 km/hr) with the engine you are building. For this case it would be proper to speed up the propeller to about 500 RPM, and use a 23 x 23 propeller (0.575 Meter diameter x 0.575 Meter Pitch). This boat could be taken on a trailer to the water.

An even smaller boat could be used, and your engine does not need to be driven at maximum power. The calculations presented above are based on maximum output of your engine at 250 RPM. Steamboat cruising is often without pushing outputs to the maximum. I would think something similar to the Elliot Bay hull would be about the minimum size for your machine.

The Phoebe, to the right Galatea, and the Margaret S under way.

Ron

DetroiTug wrote: ↑Mon Feb 22, 2021 8:51 pm Very good work as usual.

You had me puzzled for a minute boring an offset diameter in the three jaw chuck. Then I realized one jaw was skipped a tooth out on the scroll, very clever.

Ron

As a side note, these can be successfully made from bronze shaft. My steam car has them and they have serviced very well.

I've just done something very similar, and completely unintentionally. I set a piece in the chuck and thought "that doesn't look too true!" When I checked I'd transposed jaws 2 and 3!