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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Re: Steam Thruster?

Post by cyberbadger » Mon Feb 19, 2018 12:00 am

Lopez Mike wrote:Why would you want a bow thruster on a one ton boat? Use a boat hook or a paddle!
To confuse the natives of course. :-P

Case in point, the Chautauqua Belle while fairly large does have electric bow and stern electrical thrusters that are primarily used for docking and manuvuering. This enabled docking directly at the Chautauqua Institution, which increased paying passengership and made it economically viable again after 10 years of being out of the water.

-CB

P.S. https://en.wikipedia.org/wiki/Chautauqua_Belle
Last edited by cyberbadger on Mon Feb 19, 2018 12:35 am, edited 1 time in total.
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Re: Steam Thruster?

Post by Lopez Mike » Mon Feb 19, 2018 12:02 am

And how big is this boat?
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Re: Steam Thruster?

Post by Lionel Connell » Mon Feb 19, 2018 6:09 am

With the buzz bomb type device you need to remember 2 things, the cycle time is extremely short, not continuous flow of steam,and, that the condensing steam is working for you, especially if you have a valve in both ends of the tube. The first short release of steam forces the water out the back, then the condensing steam pulls the water in the front. I have seen one in operation in a model and it propelled the model along.
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Re: Steam Thruster?

Post by Lopez Mike » Mon Feb 19, 2018 6:14 am

I'll bet it was a total steam hog.

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. Happens in turbo pumps all too often.

Right Fred?
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Re: Steam Thruster?

Post by DetroiTug » Mon Feb 19, 2018 10:09 am

"I have seen one in operation in a model and it propelled the model"

It's really impossible to truly scale any sort of vehicle up or down. Take for instance the Piper SuperCub which weighs around 900 pounds, a 1/4 scale model of it typically and must weigh around 1/100th of that for it to have any chance of comparable performance. What works in a model weighing a very small fraction of it's full sized counterpart is an invalid comparison.

A buzz bomb steam thruster would be a great condenser and yes it would create a large amount of vacuum, unfortunately very little pressure of the steam would transfer to the chamber. Steam being a gas with no mass would cool to ambient and 0 psi or inches of vacuum which would happen in a few milliseconds and would produce very little pressure in the chamber if any, and if it were very efficient in creating a vacuum in the chamber. this vacuum would have to be overcome to complete the cycle with any measurable discharge from the chamber.

"They didn't really have a full understanding of thermodynamics when Watt and Fitch were around"

I would do a little reading on that. Not so sure about Fitch, but Watt, Bolton, and many others around that time had a very keen knowledge of thermodynamic principles. What most people know about Watt was that he was not in favor of high pressure steam, but it was because of safety reasons, not because he misunderstood the benefits of high pressure steam. In retrospect, he was really right about that as metallurgy of the day was inadequate to rely on for safe boiler construction. Many of the early high pressure engines blew up and did so with regularity for the next hundred years until widespread availability of Bessemer type steel came along. It took a few daring sorts like Trevithick, Murdoch and several others to persevere and make high pressure steam a practical method of power. The benefits of high pressure which were too many to not utilize, outweighed the safety concerns and the Newcomen and Watt type vacuum engine designs were abandoned.

-Ron
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Re: Steam Thruster?

Post by Lionel Connell » Mon Feb 19, 2018 10:52 am

The original post did not ask if it were possible to make a steam thruster that is more efficient than that of the steam turbine of a modern war ship, the post asked if there is a way to do it. If indeed the device is to be used as a bow thruster then it is going to be used for 0.0001% of the operating time of the boiler so who cares how inefficient it is? The responses to a method that I have seen work are amazingly negative, and a very good indication of why more than 90% of the posts on this forum are from just 5 people. Dominating every conversation with outbursts of negativity gets you just what you have, a very small circle of listeners.

By the way, I have been building and flying radio controlled models for the best part of 40 years, some of them my own designs for use in aerobatic competition, I do understand something about the performance effects of scaling a design up or down.
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Re: Steam Thruster?

Post by fredrosse » Mon Feb 19, 2018 11:12 am

Fredrosse: Same for a bow thruster, they use a relatively large propeller to work effectively, engineers figured all this out many decades ago.

CB: "This confuses me. In comparison to the vessels main propeller aren't bow thruster propellers usually smaller?"

ANS: Yes, they are considerably smaller, but please realize that the thruster's job is not to use as much power as the main engine on a ship or boat, it is just to produce a small side thrust to help in docking the vessel. That is why they have propellers that are smaller than the main propulsion propeller.

Lionel: "If indeed the device is to be used as a bow thruster then it is going to be used for 0.0001% of the operating time of the boiler so who cares how inefficient it is? The responses to a method that I have seen work are amazingly negative,......"

ANS: The technical issue here is that, with a steam jet type thruster needing several times the entire steam capability of a typical launch boiler to produce a few pounds of thrust, it just is not worth further evaluation. The responses I see are not so much "negative", they are just presenting truth about technical questions.
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Re: Steam Thruster?

Post by DetroiTug » Mon Feb 19, 2018 12:13 pm

"amazingly negative, and a very good indication of why more than 90% of the posts on this forum are from just 5 people. Dominating every conversation with outbursts of negativity gets you just what you have, a very small circle of listeners.""


I wouldn't tolerate it if I were you, you should start your own steamboating forum and see how well it fares, then you can compare. Would really shine the light on the negative players here. Its insulting to claim that a few people disagreeing with someone or offering an opinion somewhat different than theirs or simply contributing to the discussion is somehow preventing discussion activity here. The steamboating hobby is minuscule by comparison to that of hobby model steam and other steam related topics. There has never been a lot of activity here. Matter of fact when Fred and I started posting here about ten years ago, this forum went for weeks and months without a post. Yahoo has a steamboating forum, you should check that out, it gets about one comment per year and no response.
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Re: Steam Thruster?

Post by Lionel Connell » Mon Feb 19, 2018 1:02 pm

Actually I spend a bit of time on various forums, and don't see the same type of response from people on other forums like I see from some people here. If you don't see a problem, well, perhaps I should not be surprised. The statistics that are available on this forum suggest that there have been many that have come and gone from here in the period that you are talking about. There are more than a thousand people in the SBA yet so few participate here on any regular basis, you don't ever wonder why that might be? I have spent a lot of time on various steam and boating forums, and I have seen a tremendous amount of input from some quite obviously well educated and well experienced people, but I never see them respond so negatively to other peoples inputs and suggestions like I have seen here. If the number of view that are reported on each topic here are to be believed then how is it that 1% of them join in the conversation? Perhaps they are afraid of the response they may get to anything that they say. Perhaps they too find themselves easily insulted.
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Re: Steam Thruster?

Post by DetroiTug » Mon Feb 19, 2018 1:46 pm

This isn't the SBA forum. They have or had one and the last time I looked it had very low discussion participation. To my knowledge this is the most active steamboating forum there is. If you know of another steamboating forum not steam or boating forum that is more active, please point it out.

Yes, several posters have participated here over the years, some simply have a few questions and once they receive the information they seek, they're gone. Most are probably just readers that don't want to participate in the discussion, which is fine. They leave it to people like me to make fools of themselves :) Lots of people start to get in to this and once they realize how expensive it is, they drop out.

Mostly I think it is Steamboaters are typically an older group and we just aren't in to social media as much as the younger traction engine, experimental and model steam crowd are whose numbers dwarf our ranks.

Also, looking at the "Views" numbers don't really mean anything on this forum, every time the thread and page within it is opened it counts as a view, even by the same IP address. 100 views in reality could only be 10-15 people.

""Actually I spend a bit of time on various forums, and don't see the same type of response from people on other forums like I see from some people here.""

I used to and me neither. This forum has always been a more professional and congenial atmosphere.
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