Affordable, long-term liveaboard?

Any more information?

I found THIS stuff. Fascinating. apparently they DO make the high speed AC motors in bigger sizes, using R/C technology. And made from car alternators!
Wow!

http://www.endless-sphere.com/forums/viewtopic.php?f=10&t=15057

http://www.fieldlines.com/index.php?topic=146394.0

http://www.rcgroups.com/forums/showthread.php?t=905411&page=10

http://www.hydrogenappliances.com/powerpmas.html

 

I don't want to rain on your idea. Just some questions.
When you haul out at least every two years, to redo the bottom paint, is there a yacht yard in your area can pick up a 66 footer? And at what cost for haul out and re-launch? and yard space is by the linear foot, too.
Have you looked into regulations regarding vessels 65 ft and over compared to those less than 65 ft?
you only show 8 ft beam and 5'9" headroom.
My 25ft boats have 6'1" headroom in main cabin and 8'6" beam. In 25ft trailersailor.
You are showing straight sides. Okay for a beamy barge. On your boat, some flare in the sides would make it more stable. The idea is, as the boat heels, it displaces more water, so rises upward. Then the boats weight keeps her stable. The amount of water displaced is equal in weight to the boats weight. Gravity keeps the boat at the lowest point it can float. Upright. Stability.

 

Similar to Bolgers "Illinois" idea, there's an interesting article he wrote about it. For coastal and inland waters and away from marinas. Max. hdrm 6'-3".

Peace.

 

Thank you for the answers, I suspect you might have the most towing/tug experience of all the forum-its combined.

i was thinking a solid link for towing, so the towed boat had identical speed, in both senses, as the tug, i.e. no ‘surging’. The spring might stop jerking etc. I was hoping this might steer a bit like a ‘bendy bus, or an articulated earth mover,. Primarily because both boats were the same displacement, and hull performance. This rarely happens in commercial towing.

Yes, the ‘hip’ intention was a kind of catamaran, but i was imagining the boats being port bow quarter, to starboard stern quarter, or vis-versa. The links using something like a truck tow ball in the deck to attach the ‘link’s”.

I look forward to hearing about your further adventures.

 

We explored very high speed motors at Boeing, where we have our share of electric RC enthusiasts as well. Our best at the time was 100kW @ 100,000 RPM. We were looking for airplane propulsion too, but a 20,000Hp electric motor is still very heavy. In many ways, a multipole motor is lighter, and certainly more reliable, and cheaper, than a large step down gearbox. At least in the Megawatt, and Gigawatt regions. Less than a Mega watt, the jury still seems to be out, on weight and cost, but noise is always an issue.

Remember, all motors are AC, some have their commutation, or inverter in modern language, mounted on the end of the motor, and are fed DC. This “DC” motor could be regulated in power, or speed, by adjusting voltage, easy in the old days.

Now, advances in power electronics, have allowed us to contemplate directly varying the frequency, and voltage, into a ‘standard’ i.e. squirrel cage, AC motor. If the motor is permanent magnet, so much the better, but it is then a bit more specialized. Finally, rotor surface speed is the limit, with wound rotors, and permanent magnets held together with sleeves of carbon fiber. As this sleeve gets thicker, the air gap widens and finally limits speed. The limits today are around 2-300,000rpm, at less than 1 kW, they are used for PC board drilling, de-hydration, and paint ‘spinneretts’ and etc. None/few are attached to a gearbox, rotational dynamics come into play.

The 1,000sq/ft seemed to be a ‘target’ so i assumed the roof for the solar collector would be ~30’ wide, X ~35’ long. I further assumed the space (deck?) under this roof would be ‘living’ area, arranged to suite, windows on the front and sides, and a deck in back. This was a ‘thought’ experiment/exercise to see if such a vessel were possible, using existing, and cheap technology and/or found items. Solar cells of any efficiency much at all are VERY expensive. The ones for our solar plane cost many millions, and the plane tore apart with wind shear in the tropopause. We had endless arguments about voltage and frequency for the motors, but finally the motor torque curves, battery weight curves, propeller efficiency curves, wing L/D ratio at altitude, and structural weight curves made a tiny ‘space’ where we could theoretically design and build a plane. Clearly we erred on the light side, though to be truthful we didn't expect shear like that at that altitude.

My work on things that looked like “Hydro-lances” showed their limits to be mainly structural, and physics. (i am a physicist). If we limited the hull length to about 2X or 3X the total beam, and limited the ‘cabin’ length to about the beam, we could get enough displacement in the hulls, at a low enough L/B ratio, to make it work. All this relied on aircraft like weight saving, not conducive to boat type costs or ruggedness. “Our” designs had a vertical support ‘wall’ for the cabin, and small filets at the base to forward hull junction. Extending this fillet as shown in the cartoons stiffens the hull vertically, but not horizontally. The ‘real’ limit seems to be how long an unsupported thin, narrow, ‘spear’ can be sticking out in front. The surface area to weight ratio is disastrous, as is the large volume/weight of unsupported bridge structure. Like a catamaran on steroids.

Trying to get/keep the propellers in the water was an issue as well, too far from the CG.

 

There are several professional seamen contributing to this forum. Some are greybeards like myself. Everybody gains in experience. We fortunate ones get to choose what kind of experience is gained.

And then there's the old saw, "Good judgement comes from experience....and experience comes from BAD judgement!"

 

Alan. As a physicist and aircraft expert, please point out the error in the following concept.

Imagine a free spinning propeller, of large size, with blades changing to aggressive pitch near the center, pitch appropriate for a turbine.
Place the prop inline and downstream of a very fast high pressure water jet.
Would the jet spin up the propeller, increasing the diameter of the water column being moved? The jet already accomplished it's work of expelling the reaction mass of water at velocity, and creating a high pressure zone at nozzle.
The prop isn't encumbering the jet, but salvaging kinetic energy from the jet accelerated water stream.
I'm imagining a turbo prop-jet for water craft.
The jet alone is insufficient in size to efficiently move the vessel, but can when augmented by the propeller.
Similar to the aircraft propjets of yesteryear, except this turbine is not encapsulated. And prop is behind jet.
Imagine if the jet were direct powered by high speed diesel, at it's optimum power/RPM range.
When the jet was shutdown, the prop was also capable of being run by an electric motor, from one RPM to a few hundred RPM, and reversible, so appropriate for maneuvering. The realm where electric drive excels.
The diesel pulls double duty, also functioning as a genset.
I believe this set of subsystems might together comprise a satisfying propulsion system for a diesel electric live aboard, all components employed where they best perform.
Please explain my error in logic or physics.

 

Very interesting, i had to read it a couple of times and i hope i understand what you are asking properly. Is this what you think about on those long night watches pushing barges? I can imagine you looking at a modern OB propeller and imagining blowing a water jet against the fins or vanes in the hub, where the exhaust goes.

What you are describing here is, in principle, the turbofan.

To be exact, your description matches the “propfan’ developed and rejected in the 80’s. In this, hot, high velocity gas, the equivalent of your water jet, powered, or spun, turbine blades optimized for the velocity and volume available. These were direct coupled (same RPM) to variable pitch propeller blades, either on the tips of the turbine blades themselves (GE) or on a shaft (PW). This failed because the turbine wanted to run fast for efficiency, and the propellers could not exceed 1,000-1,500 rpm as the tips would then exceed the speed of sound. This latter causes noise such that everyone in earshot throws up uncontrollably. See below for the final solution, the compromise of the Turbofan.

A water jet, a narrow, high velocity column of water, imparts energy by impacting something where the inertia of the water is converted into rotational energy (typically). Classically this would result in a “pelton’ wheel turbine, where the transfer is dependent on the wheel running in air, a low density, low drag fluid. As the tips of the wheel are traveling at just less than the water velocity, it is this ‘slip’ that represents the power produced. Just one nozzle will produce violent pulsations of power against your propeller blade sections as they pass, and this will be felt by the shaft, bearings etc. You could design for this, but its heavy.

If you increase the number of nozzles, so the complete ‘turbine’ is bathed, you will need a lot of smaller blades, and at a number that does not divide into the nozzle number. These blades might need to be quite ‘thin’ and therefor not much support for a big propeller blade. They might also be shaped such that water passing across their back side will produce a low pressure, so more ‘thrust’, though cavitation might be an issue, depending on water and blade velocities.

If you increase the number of ‘nozzles’ to infinity, and have a nozzle ring, then for greatest energy transfer, you need a series of blades, necessarily small, so all the jet is captured, and has its energy transferred.

Due to its nature, a high speed jet of water wants to transfer its energy at a similar high speed, a very small slip, so the blades it is impacting need to be at a similar high local speed. The hub of a propeller it classically at a very slow speed, depending on diameter.

Forms of boat propulsion;

A water jet is a narrow column of water traveling very much faster than the boat. It typically supplies reaction energy by expelling this column into the air behind the boat. Neither the pump itself, nor the reaction energy is particularly efficient, but it is exceptionally useful where people may be damaged by a propeller, and/or rocks on the bottom reduce available running depth. Its not as good in mud, soft debris can be sucked into the pump intake, and clog things up.

When a classic propeller tug is traveling slowly at full power, the propeller produces a similar column of water behind it, i think its called a ‘race’. This column of water is traveling much faster than surrounding water, and though its inertia is being transferred, it is inefficient due to the ‘sheer’ action between the high speed column and the slow ambient water. It must result in a lot of deaf fish.

Finally, there is the wake of a correctly sized propeller, (I've seen it on cruise ships) where you see a distinct corkscrew, or spiral, of disturbance traced by the propeller tips. Is this local turbulence, tip vortex, or cavitation? In this case the column of water produced by the propeller is barley faster than the vessel, and very efficient therefor.

The classic issue here is blade velocity. The turbine wants to go fast, and the propeller wants to go slow. One answer is to put the turbine blades on the tips of the propeller. This necessitates having a ‘ring’ around the propeller blades, so its not really a propeller any more. Aircraft have tried this, tip driven lift fans, the Ryan XV-5 for instance. http://en.wikipedia.org/wiki/Ryan_XV-5_Vertifan

We/i did a lot of work on this principle at Boeing for the F-35 competition, but could never get satisfactory results.

For you I pictured a propeller with a ring of turbine blades on it, in a shroud, but having the turbine running in water raises the rotational drag to excessive levels. It might look a bit like a shrouded propeller, but be very complicated, and have a ‘fan’ rather than a propeller.

In a gas turbine, the jet exhaust is very fast, 600+ MPH and fairly narrow, the diameter of the exhaust duct. The large difference between this jet speed, and the local air speed, the ‘shear’, causes a lot of noise, and general inefficiency.

The turbofan, by contrast takes this high speed ‘jet’ and expands it through a set of turbines, where the gases are cooled, and reduced in speed, by expansion, giving up their thermal and kinetic energy. The ‘last’ turbine set, and, slowest rotationally, are direct shaft connected to a single set of ‘fans’ at the front of the engine. The rotational speed of this shaft is a compromise, between the high tip and blade speed desired by the turbines, and the low tip and blade speed of the fan. This is accomplished by having very large diameter turbine disks, so the tip speed is as fast as practical, and having a shroud around the fan blades so they can exceed the speed of sound benignly.

In development is the Geared Turbofan. This allows the turbine to run as fast as it likes, while the ‘fan’ runs as slow as it wants. The gearbox losses, and especially its weight are horrific, at least in aircraft terms, but the engine companies are persisting. I want to use the gearbox heat, hot oil, to de-ice the wings, cooling the oil in the process, but this is not currently acceptable politically. The airlines own the engines independently from the airplane, and can change them if they want.

Both the turbofan and geared turbofan are reaching the limit of their development. The fans are now so big, their stalled drag is too much for the remaining engine to ‘drag’ around for a missed landing approach! The next generation of efficient airplanes might use something like this. Specifically developed to address the issues of economy and stalled drag. It is also the worlds first automatically variable cycle turbofan/turboprop.
http://www.google.com/patents/US8689538

The turboprop, is different again. In this, the gas turbine merely produces hot gasses, as does the gas turbine in a ship. This hot gas is then allowed to cool and slow as it expands through the turbine blades/discs. These turbine disks can run at any speed below the heat creep speed of the blades material. Ships especially like a long life from these components. In both cases, these high speed shafts are connected through a gearbox to a propeller. In the case of an airplane the gas generator might do 7,000rpm, the turbine 6,000rpm, and the propeller 1,000rpm. Airplane propellers are limited by tip speed, less than the local speed of sound. Ships, the gas generator might do 7,000rpm, depending on size, and the turbine 5,000rpm (they are larger), and the propeller 80?rpm.


Running a high speed water jet into a ‘slow’ propeller is very inefficient, and a ‘fast’ propeller is very inefficient. To match these differences, you need a gearbox, the very ting we are trying to avoid. If the boat is fast, use the water jet directly.

Now possibilities;

A classic fixed pitch propeller has a ‘cubic’ thrust curve with RPM, so it uses little power at low RPM. If you put a ‘standard’ 12 pole squirrel cage electric motor physically as the propeller shaft, and drive the shaft from a diesel engine gearbox, the motor will be benign. You could de-clutch the diesel and gearbox, and drive the electric motor from an inverter. With careful choice of propeller, you could have a 10hp electric at 600rpm say, and 40hp from the diesel at 800rpm? Not sure of the numbers, but you get the idea.

Taking Noah’s suggestion, you could mount a car or truck alternator as/on the propeller shaft, and use it as a alternator/generator whilst the diesel was running. Then, with the diesel (and preferably gearbox too) de-clutched, run the car alternator as a permanent magnet 3 phase AC motor. Again, about 10hp perhaps, and 40 from the diesel. This is quite similar to old diesel electric submarines, and they too had a big speed difference between electric, and diesel propulsion, and the same propellers for both. You shouldn't need an expensive variable pitch propeller either.

Another possibility, mounting the ‘water turbine’ inside the boat. In this case you are better off with a hydraulic motor. These are inherently slow speed, and in fact a hydraulic pump running at Diesel speed, and a hydraulic motor running at propeller speed might work very well. In the 787 we did this, and added a electric motor running a hydraulic pump for back up. In fact it might be rather higher efficiency that any water pump/turbine combination, no losses to stray water. The hydraulic system is ‘closed’ in this sense. I have heard of, but never seen, hydraulics using water as an operating fluid, but water is pretty abrasive, unlike hydraulic oil.

Some warships use Combined Diesel and gas turbine (CODAG), where the same propeller is driven at different RPM’s by diesel or gas turbine. Mostly both use gearboxes, and the Americans use Variable pitch propellers too, but early (UK?) ones had fixed pitch propellers, direct drive diesels, and gearboxes on the gas turbine only.

In conclusion: the water jet requires a high (lateral) velocity turbine blade to be efficient, the propeller blade needs to be relatively slow in lateral velocity to be efficient. Even with the turbine blades on the outer rim, the difference is not enough. Were you to apply a water jet to the vanes inside an OB propeller, with the ‘vanes’ correctly shaped, and curved, it would spin fine in air, but not transfer enough torque in water.

 

Thanks. I was certain there was something I was missing in the concept. If it was workable, somebody would already be using it. Now I know what I was missing. Knowledge. thanks for the lesson!

 

Keep thinking, these approaches can sometimes yield results. I thought long and hard before accepting that technology had not changed to where your approach might work. The turbofan was technically not possible for many years until the metallurgy of turbine blades advanced enough, and even then there were many false steps (RR for instance).

More recently, fluid couplings were revolutionized by the incorporation of non-newtonian fluids. These fluid couplings exploit the fact that these non-newtonian fluids will allow ‘slip’ where the shear velocity is low, but lock ‘solid’ when shear velocity is high. Land Rover/Range Rover were the first to use this in their ‘locking differentials’ paying a royalty to Ferguson tractors.

Equally, electroheological fluids can allow huge differences in viscosity by the application of a magnetic field to a fluid. This is used in variable rate shock absorbers among other applications.

I could have just said that gearboxes, chain drives, hydraulic pump/motor sets, and to a certain extent fluid couplings act as torque multipliers, but that electric motors, reaction machines, and turbines of most types are, at best, constant torque. But that would have been less helpful.

So keep thinking, sometimes it is technology that is lacking, sometimes it needs a combination of technologies, sometimes a complete rethink of what people are trying to accomplish. Any of these can trigger a new development.

 

Bet you know a thing or two about magnus effect.
I'm considering building a Frettner cylinder from old drum sets I have stashed away.
Played jazz professionally in my teens. Acumulated lots of drums in the half century since.

 

Yes i know a bit about Magnus Effect, and a couple of attempts to implement them, Cousteau for example. I suspect you would be better off using old oil drums for the Frettner cylinder, and use the drum sets for collateral.

Why do we not see more boats/ships pumping air under their bows as a friction reducer?

Perhaps the same reason commercial airplanes do not use laminar flow, or ribletts, or e-beam, or surface heating to reduce drag.

Laminar flow does work, but requires such a smooth and clean surface that it is not practical. For instance, even a fly spot on the surface will destroy the laminar flow, so we, the manufacturer, cannot ‘guarantee’ the continuous existence of this flow during a flight. Hence the regulations will not allow the plane to depart with less fuel than needed for a ‘normal’ flight with the required reserves. One might get better fuel economy for some of the flight, but the real gain would be carrying less fuel (weight). Instead we concentrated on “aft loaded” wing sections, and the ‘potato chip’ wing where local curve is customized to exploit local flow.

Equally, ribblets, minute chevrons proud from the surface of the airfoil also work, but must be perfectly clean, hard and sharp, to work at all. Even when made from antistatic materials (self cleaning), they still weigh more than the fuel they save.

Finally, surface heating, and even active airflow control using e-beams, also work, but the energy required would need another engine, and lots more fuel than they save.

How about boats/ships.

Sound of joints creaking as he climbs on his ‘hobby horse’ or ‘soap box’; I think most of the development, and inventions, in the ‘pure' sciences, like engineering, chemistry, etc have been done. The next generation of such developments and inventions will come at the intercies of sciences, between chemical and electrical engineering, between mechanical and biological engineering etc. The exception being materials. These are being improved and developed all the time, and sometimes allow advances in current technology. Hence we should all be asking questions as did Yobarnacle, and Noah.

Someone on the forum suggested that Magellan had it right, and was the first successful circumnavigator using solar power. Equally, i build my boats out of wood, but even then they are not like Magellan's. They tend to be a wood core encased in long chain polymers, so though the wood bit is sort of sustainable, much of the rest is not. i suspect conservation is a good answer, and re-purposing a used FG boat a sound approach. Well done Yobarnacle, for re-using where you can, and reducing your use of other resources.

I “Invented’, found actually, bugs that eat diesel and produce electricity, but sometimes i wonder if i shouldn't have trained them to eat seawater and produce electricity.

 

Started a new thread here.

http://www.boatdesign.net/forums/pr...-frettner-rotor-project-50587.html#post690828

 

My long term research projects are; (among several others)
1. a catamaran design with hovercraft function that can be made with acceptable drag and offshore stability.
2. a boat hull material with chevron texture and trained pilot fish to clean them constantly.

Sailor Alan, do you know where I can find transmission gear efficiency of keel drive, sail drive, outboard drive and inboard drive? Where can I find transmission efficiency of chain drive, V-belt, bevel gear, planetary gear, gear belt. etc?

I am thinking, affordable long term live aboard cruiser should be made with Chinese parts, designed sustainably, assembled with local labor. Chinese Yanmar clones, Chinese RC motors in series, Chinese batteries, Chinese PV panels, Chinese resins... Dang! This is totally against my political philosophy but my practical engineering side says otherwise...

 

Build a traditional Chinese junk!