Steam Thruster?

A special section just for steam engines and boilers, as without these you may as well fit a sail.
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cyberbadger
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Re: Steam Thruster?

Post by cyberbadger » Mon Feb 19, 2018 3:40 pm

I think just about everybody on this forum comes in with their own set of assumptions. When these assumptions are really far from each other it is easy to miscommunicate.

I have a lot of ideas and I love to brainstorm. Other folks come in and want to dissect ideas and debunk them critically.

Sometimes that is really what is necessary because of the person doesn't have a firm grasp of the idea it could potentially be very dangerous(Read: Potentially Fatal). People already entrenched in the hobby of steam at any scale or type don't want anyone hurt, but they also really don't want their hobby eliminated by yet another idiot who did not grasp an important concept and went and got people hurt or killed. (The History of Steam IS written in blood.)

I feel that this reaction is pretty easy to trigger accidentally on steam forums.

This reaction is for good reasons, but sometimes it really gets in the way of brainstorming. And yes, most of the stuff has been tried before and none of us is really going to come up with something earth shattering. This has all probably done before. But does that mean it's not worth doing? No, because it's a hobby. It's a hobby in obsolete technology. There is little about it that really is practical in modern times. It's expensive, it's inefficient, and takes a lot of work and dedication to make a steam launch. And it's definitely worth the experience. Julius Caeser had a list of 3 things every man should do in life, one of them was write a book. On my list of things to do in life I feel that anyone even slightly mechanically inclined should consider making a vehicle of their own design - because it is awesome when your creation comes to life - especially running with steam. It's can be truly inspirational.

-CB
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Re: Steam Thruster?

Post by Lopez Mike » Mon Feb 19, 2018 4:15 pm

I don't think it is some terrible negative thing to observe that many people new to the forum and to steam tend to want to re-invent the wheel. Or think that starting with a square wheel is a reasonable idea. Especially when their first improvement of the square wheel is to a triangular one! Fewer bumps, you see?

It is as regular as the seasons to have someone decide that a technology that matured a hundred years ago should be turned on its head overnight. It's just not going to happen. There is no way that one of our little boats is suddenly going to double its efficiency. No way.

I think the regulars here have bent over backwards to be polite in the process of saying essentially that some idea or the other is nuts.

Next we'll be asked to respond rationally to perpetual motion types. I don't need to see that sort of thing first thing in the morning with my orange juice.

Jump on me when I'm wrong about steam things. You'll have an easy target. That happens a lot!
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Re: Steam Thruster?

Post by lostintime » Tue Feb 20, 2018 3:04 am

Lopez Mike wrote:
Condensing can happen really, really fast. That's what cavitation around a propellor is. If there is no dissolved gas, the collapse is so violent that it can erode metal.
This is by no means an exaggeration, the pic of the vessel I posted in my question on thermosiphon tubes failed because of this. An upstream valve failed (shut off valve had been used as a throttle valve and wire pulled the seat) this allowed vapor to condense in the vessel while it was off line (others still running), erroded through the siphon tube then through the vertical tube.
edit: there was a electrically operated pressure regulator valve that vented pressure when the vessel was offline
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Re: Steam Thruster?

Post by cyberbadger » Tue Feb 20, 2018 4:17 am

Keep in mind that if you are talking steam capacity, you don't get it - a thruster is intermittent use - steam capacity of what is in the boiler should be plenty.

A steam powered thruster does not need to be efficient *at all* to be useful.

It's been done already on a steam power vessel, e.g. the Chautauqua Belle. But they run off of batteries. In their current configuration, the energy from their batteries does not come ultimately at this time from steam - I think they charge it off of the d i e s e l generator. When they had the Skinner uniflow genset working, conceivably it could have been a true hybrid steam powered thruster.

Skinner Uniflow 30KW->Gel Battery Bank ->Electric Thrusters(Bow and Stern)

So it has been done, and that's an example of steamer who has it. This is not fantasy. And yes the Belle is large, who cares - its a good example because it made the difference whether this steamer was operational or not.

Here were the sba rules for one of the outboard competitions... http://www.steamboatassociation.co.uk/event-822015
Somebody tried with ejectors - which is an example of an attempt of more direct steam thing.
I don't want to reprint from the Funnel issue because I know those Brits don't really understand the concept of fair use. I can't find the exact results but an array of 2 or 4 ejectors was tried, and it went nowhere at the dock - it actually drifted backwards an inch. :/

Now let me rephrase the OP:

If you were forced to build a steam powered thruster for a boat, what would that look like?

Would it be electric like the Belle? Hydraulic? Pneumatic? Something direct steam(we have already received technical booing from the thermodynamics crowd on this approach), other?

If your answer is you would never ever make one, just don't post.

-CB
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Re: Steam Thruster?

Post by TriangleTom » Tue Feb 20, 2018 4:56 am

Lopez Mike wrote:I don't think it is some terrible negative thing to observe that many people new to the forum and to steam tend to want to re-invent the wheel. Or think that starting with a square wheel is a reasonable idea. Especially when their first improvement of the square wheel is to a triangular one! Fewer bumps, you see?
That's the hardest I've laughed this month.

CB, to answer your question the most practical solution for a small vessel would probably be something like a trolling motor that you run off the boat's steam charged electrical system.
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Re: Steam Thruster?

Post by Lopez Mike » Tue Feb 20, 2018 5:14 am

That joke is an old one from a seminar I gave on customer satisfaction.

The story goes that the first cave man invented the first wheel but it was square. The feedback from the field was that the ride was too bumpy. That there needed to be fewer bumps. Soooo . . . .

Depends on who writes the spec.
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Re: Steam Thruster?

Post by cyberbadger » Tue Feb 20, 2018 5:34 am

Lopez Mike wrote:Depends on who writes the spec.
The spec is as flexible as you are in this case....

-CB
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Re: Steam Thruster?

Post by lostintime » Tue Feb 20, 2018 12:45 pm

If I had to do it I would belt drive a bell and gosset centrifugal pump (has its own bearings and seal) geared way up off the main motor with an over centering idle pulley leve to engage it, (think riding lawn mower),, run the discharge to a manifold with 5 valves, 4 for a pipe going to each corner, and one pointing forward as a by pass and to help balance the prop ticking over
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Re: Steam Thruster?

Post by DetroiTug » Tue Feb 20, 2018 3:04 pm

As TriangleTom mentions, just a trolling motor with adequate thrust will work. It takes quite a bit of thrust to move a 2 or 3000 pound boat fighting a crosswind perhaps. Some trolling motors for fishing boats are over a hundred pounds of thrust. One advantage to the trolling motor is it can be used in an engine breakdown situation to get in with.

For a boiler only solution, steam could be tried, but a steam thruster (ejector) with adequate velocity to have comparable thrust of a simple trolling motor it would likely have to be very large. I have a 3/4" Penberthy Ejector (professionally designed assumed high efficiency)fed with a 3/8" steam line, the exit water velocity, I'm guessing would only produce around a pound of thrust, if that. Smallest electric trolling motors are around 17 pounds thrust and I doubt even they would be effective on a 2000 pound boat is a cross-wind situation.

An easy solution would be to use boiler water instead of steam through a nozzle (piece of pipe). IF the boiler has enough reserve to do such a thing without the risk of resulting in a low water situation afterwards. High velocity boiler water which will not condense immediately would provide considerable thrust. For a thruster, really all that is ever needed is a small kick to either side. --- This is actually a pretty good simple idea, I may try this on the Tug. Andy, this would be easy for you to try, pipe your blow-downs forward and each to either side with submerged exits.

-Ron
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Re: Steam Thruster?

Post by SL Ethel » Tue Feb 20, 2018 3:16 pm

I second the trolling motor idea. You can still use steam for the battery charging, and so be a 100% steam powered vessel (after all, the Normandie had a steam electric propulsion system, so you are in very good historical company there).

My thought is that even on a small boat, if a thruster is to be useful, it should be absolutely as reliable as possible, and powerful enough to really get the job done, without taking much of the operator's attention. After all, it won't help you single hand your boat if you have a bow thruster that takes 5 minutes to set up before use and requires 100% of your attention during a docking operation, when presumably your attention will need to be elsewhere.

To that end, I think a trolling motor is your best bet. You could mount it so that it could be swung down into the water in a matter of seconds when you are approaching the dock (generating no drag the rest of the time), and it could be controlled reliably by a switch right at your steering and engine operating station.

Good luck with it. I think anything that makes single handing safer and easier makes us more likely to get out on the water, which is always a good thing.

Cheers,
Scott
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