small steam engine?

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steamingmartha
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small steam engine?

Post by steamingmartha » Wed Mar 27, 2019 11:09 pm

Hello from New Zealand! I have a 14' kauri clinker launch which is fitted with a 6 bhp Petter single cyl. diesel. It all works well but of course it's a noisy b****y thing. My question to the forum is this: is there a 4 or 5 hp steam engine available in kitset form somewhere in the world? I've been for rides (sails?) in a few steamboats here, and of course, silence is golden out on the lake. Lovely! At this stage I envisage a lpg fired boiler for convenience. Meanwhile back in the shed, someone has just offered me a large 18 volt motor...Hmmmm. All ideas gratefully received here or atepushrods@gmail.com
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Re: small steam engine?

Post by Mike Rometer » Thu Mar 28, 2019 9:47 am

It has to be said that there is nothing quite like the charm of steam, particularly on the water. For 14 ft you probably won't need as much as 5 HP with steam. Something like a Stuart 5a single should do it. Those are available as a kit of castings requiring machining, there may even be a stockist somewhere in NZ. Take a look on their website @ https://www.stuartmodels.com

I would also suggest that you get in touch with your local Model Engineering Soc (there are loads in NZ.) they will be able to give some guidance and maybe assistance too.
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Re: small steam engine?

Post by TahoeSteam » Thu Mar 28, 2019 3:35 pm

Welcome to the forum.

I agree with Mike, 5hp is probably overkill for a 14' launch. A boiler required to feed that hungry Lil guy would be rather large for a boat that size.

Suitable complete running engines should be relatively easy to find amongst the model engineering crowd.
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Re: small steam engine?

Post by dampfspieler » Thu Mar 28, 2019 9:16 pm

What displacement does your boat have? You will need 2.2 kW per 1000 kg water displacement of the boat.

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Re: small steam engine?

Post by steamingmartha » Thu Mar 28, 2019 11:18 pm

Thanks for your replies. I was guessing about the 5 hp, forgetting of course that steam hp is bigger (better?). With the Petter and 1:2 reduction in the gearbox, my prop speed would be 600 to 1600 rpm, 9" prop and no room for bigger, and the 4 knot speed seems about right for a 12' waterline length. The Stuart 5a could be the thing! it's rated at 1.5 hp at 300rpm. Is that max rpm I wonder? Would there be enough torque to gear up significantly? I could use chain and sprockets (yes, I used to be a motorcycle mechanic).
Also, how would I calculate the displacement? Waterline is 12' x 5' beam. OA 14' x 5'5".
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Re: small steam engine?

Post by steamingmartha » Thu Mar 28, 2019 11:27 pm

ooops! typo. That's 1.5 hp @ 800rpm
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Re: small steam engine?

Post by fredrosse » Fri Mar 29, 2019 3:22 am

"I was guessing about the 5 hp, forgetting of course that steam hp is bigger (better?)."

In real engineering, horsepower is horsepower, no matter steam or diesel or electric. It is however common for these numbers to be inflated by advertisements, etc.

In any event, the FAQ section of this forum will provide fairly accurate numerical data where you can determine the hull speed, power required to drive your boat, size the boiler, and size the engine. The statement that you will need 2.2 kW per metric tonne of displacement is very conservative, that is 3 real horsepower per tonne at displacement hull speed, which corresponds to a little over 4 knots for a 12 foot waterline length. To propel the boat at 4 knots will actually require about 1 horsepower per tonne on the propeller shaft driving a 9 inch prop.

An electric line came down on my steamboat years ago, burning the launch completely. I knew it would take years to replace the steamer, but I wanted to cruise around with the steamboat group, so I decided to quickly build an electric launch. I purchased an O'day Javelin hull, 14 foot long x 5.5 ft beam, cut out the centerboard well and glassed in a propeller shaft tube. I was able to cruise around with the steamboats at 4 knots, all with a 0.75 horsepower 24 volt PM motor, with belt reduction to 400 RPM, driving a 14 x 17 inch 3 blade propeller. Very similar to your situation.
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Re: small steam engine?

Post by Lopez Mike » Fri Mar 29, 2019 3:29 am

Gearing up will be a good thing as the 5A will be having a hard life if you turn it up too high. Slow is peaceful.
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Re: small steam engine?

Post by dampfspieler » Fri Mar 29, 2019 3:43 am

For such a small vessel i recommend a reinforced STUART 3 (original 1 1/2 + 2 1/4 x 1 1/2", reinforced 40 + 60 x 40 mm) and a ofeldt-typ-watertube-boiler.
That is a very powerful boiler. I have successfully tested my steam engine (double acting single 60 x 74 mm) with such a boiler (my little LOCKENWICKLER-Boiler).

https://youtu.be/AgGv3aA5R78

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Re: small steam engine?

Post by dhic001 » Sat Mar 30, 2019 8:39 am

Hi Steaming Martha,
Where abouts are you In New Zealand? I'm north of Auckland.
Daniel
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