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  #21  
Old 01-27-2013
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Re: Towed Generator that We Really Need

Quote:
Originally Posted by THEFRENCHA View Post
What about these ?
Hydrogénérateurs Watt&Sea : votre voilier autonome en énergie |
They are on most racing sailboat such as IMoca During the Vendee Globe and have proven to be effective and reliable with minimum drag
See the post directly above your post, where I refer to them as "the very best water generators." And I will quibble with your description of them as 'reliable'. At least three W&S hydrogenerators have failed in this edition of the Vendee, causing (indirectly) one sailor to retire from the race and the others to expend much effort on repairs. They probably all hit debris, but that fact touches on a basic issue with hydrogeneration. The units are all vulnerable to impacts & entanglement. Or shark attack, in the case of tow generators According to Beth Leonard, Water generators rated second (after watermakers) in the SSCA's "Products most prone to breakdowns" survey -- 28% per annum. Small sample size, but they do have a poor reputation for reliability. As do wind turbines. They work hard in snotty conditions.

A combined troller/generator as proposed by the OP would help mitigate the cost by serving two purposes; OTOH, it would suck to have thieves steal both your outboard & power generating device, or to hit a basking sunfish & lose not only your daily watts, but your water taxi too.
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  #22  
Old 01-27-2013
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Re: Towed Generator that We Really Need

Quote:
Originally Posted by guitarguy56 View Post
These look nothing more than glorified trolling motors with the proper pitch props...
And said proper-pitch props matched to an efficient alternator, which in turn is matched to the fluid speed it will operate in. Exactly right. But all those conditions have to obtain for a hydro-gen (or wind turbine) to create meaningful amps. Ya can't just use a thrust propeller attached to any old DC motor intended to spin at a totally different RPM range and expect good output. The Watt&Sea is, indeed, basically a reverse-engineered trolling motor. But it's a very clever one, and probably about as optimal as you are likely to see, anytime soon.

Could you reverse the current & use it as an outboard? Probably. It wouldn't move your dinghy real fast, tho. Could you change to a different prop and use a digital controller to optimize it for outboard use? Ah. That's the question under discussion, here. I think you could, with some (acceptable?) sacrifice of performance in each mode. But the point is, the unit would need to be designed from scratch as a dual-purpose machine, and you could not use the same prop in each mode. Begin with those criteria and realistic performance goals, and you could probably build one. And make a small fortune... into a much smaller fortune.
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  #23  
Old 01-28-2013
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Re: Towed Generator that We Really Need

Quote:
Originally Posted by bobmcgov View Post
And said proper-pitch props matched to an efficient alternator, which in turn is matched to the fluid speed it will operate in. Exactly right. But all those conditions have to obtain for a hydro-gen (or wind turbine) to create meaningful amps. Ya can't just use a thrust propeller attached to any old DC motor intended to spin at a totally different RPM range and expect good output. The Watt&Sea is, indeed, basically a reverse-engineered trolling motor. But it's a very clever one, and probably about as optimal as you are likely to see, anytime soon.

Could you reverse the current & use it as an outboard? Probably. It wouldn't move your dinghy real fast, tho. Could you change to a different prop and use a digital controller to optimize it for outboard use? Ah. That's the question under discussion, here. I think you could, with some (acceptable?) sacrifice of performance in each mode. But the point is, the unit would need to be designed from scratch as a dual-purpose machine, and you could not use the same prop in each mode. Begin with those criteria and realistic performance goals, and you could probably build one. And make a small fortune... into a much smaller fortune.

OK... understand the pitch principal on the thrust for the trolling side... I am a propulsion engineer with decades of jet turbine experience... that said... we used 'variable pitch vanes' to alter the compression and exhaust of gases to achieve maximum performance in the engines, we also tried variable pitch compressor/turbine blades, they are also used in variable pitch props on aircraft... well if the maker/inventor of the unit you devise in your last paragraph can incorporate the 'variable' part of the prop in such a way... then in the thrust mode it would operate like any regular trolling motor... push a button and it changes the pitch of the blades to the generator mode... then it might be reasonable product and many might/will be sold... the problem is the unit will look like the rotor of a helicopter to vary the pitch of the blades... very complex, expensive materials, and the loads on the the hardware would be tremendous and not make this a viable product... plus any little piece of debris on the rotor would disable it's functionality and then it's just another piece of 'crap'...

Nick
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  #24  
Old 01-28-2013
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Re: Towed Generator that We Really Need

Quote:
Originally Posted by guitarguy56 View Post
OK... understand the pitch principal on the thrust for the trolling side... I am a propulsion engineer with decades of jet turbine experience... that said... we used 'variable pitch vanes' to alter the compression and exhaust of gases to achieve maximum performance in the engines, we also tried variable pitch compressor/turbine blades, they are also used in variable pitch props on aircraft... well if the maker/inventor of the unit you devise in your last paragraph can incorporate the 'variable' part of the prop in such a way... then in the thrust mode it would operate like any regular trolling motor... push a button and it changes the pitch of the blades to the generator mode... then it might be reasonable product and many might/will be sold... the problem is the unit will look like the rotor of a helicopter to vary the pitch of the blades... very complex, expensive materials, and the loads on the the hardware would be tremendous and not make this a viable product... plus any little piece of debris on the rotor would disable it's functionality and then it's just another piece of 'crap'...

Nick
Excellent points, Nick. In the other thread, we discussed the possibility of using variable props like the MaxProp for generating. More and more sailors are opting for the expense and complexity of these things anyhow, and they do hold some attraction for hydro-gen use -- esp. as part of a hybrid driveline. The racing version of the Watt&Sea has a hydraulic variable-pitch prop to maximize output/drag ratio across the wide speed range of 'Open' Class boats. It costs around $7500 IIRC.

Truth is, with solar PV down to ~$1US per watt and improvements in flexible films, power density, and shading compensation, that is increasingly the most attractive RE solution for boaters. As hellosailor noted, people have been trying hydro-gens for five decades without much traction. Now, as we get the boat speeds, rare-earth magnets, and composite materials that make good ones feasible, better PV has made them irrelevant. Their time may have gone before it has come.
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  #25  
Old 01-28-2013
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Re: Towed Generator that We Really Need

Quote:
Originally Posted by bobmcgov View Post
... costs around $7500 IIRC.

Truth is, with solar PV down to ~$1US per watt and improvements in flexible films, power density, and shading compensation, that is increasingly the most attractive RE solution for boaters. As hellosailor noted, people have been trying hydro-gens for five decades without much traction. Now, as we get the boat speeds, rare-earth magnets, and composite materials that make good ones feasible, better PV has made them irrelevant. Their time may have gone before it has come.
The huge costs to many customers of these products are the reasons many of these products do not make it very far in the market... many of these companies and start-ups fail due to huge costs in engineering, tooling, manufacturing, certifications only to see not many customers and hence...

Solar PV is the best return in terms of watts/cost... they have come a long way since their initial use in the space program... but unlike computer chips which have undergone magnitudes of orders every two years... the technology for propulsion units and energy have not... if propulsion would be similar to computer chips in terms of magnitudes of advancement we would have 'Star Trek' type propulsion and energy from nuclear power units the size of our Honda 2000 generators producing 100Kws or more in power... Current propulsion for aircraft really has not advanced since the engines of the 1960's... the only improvements are small ones and mainly lightweight high strength materials, and improvements in efficiency, etc....

So there are many new exciting technologies in the labs at MIT, Scandia Labs, and many labs in universities with energy producing devices... one in particular I'm looking into is use of saltwater right from the sea to produce electricity and so far the idea is in the lab stages and produces a small amount of electrical output in milliwatts but it may be many decades away from a real product due to finding the proper membrane material... but imagine the bottom of a boat hull with this device maybe painted to the hull producing 10Kw or more depending on hull size...

Nick
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  #26  
Old 01-29-2013
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Re: Towed Generator that We Really Need

[QUOTE=Stumble;981887]Chuckles,

1) prop size was optimized for pushing the boat, not turning a shaft. Pitch, shape, are backwards from what you really need for a water turbine

How about using a the small outboard system of reverse, prop leading for generator turn 180* bypass charge controls, motor away

Should be better then dragging it the other way, you would still need to compimise on the prop some.
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  #27  
Old 01-30-2013
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Re: Towed Generator that We Really Need

That is a joke, right?

First paragraph:
Statement of problem and declaration that people trying to solve it have no clue and little chance of success.

Second paragraph:
Stating the obvious about trolling motors with a gentle, but unfounded feature presentation of Torqeedo.

Third paragraph:
Statement of own superior qualification, and semi-clear suggestion how not glorious self, but Torqeedo could and should solve stated problem.
Very clear estimates of prices, engineering solutions proposed, without ANY base.

Closing:
Appeal to "Marine Industry" to listen.

Are you TROLLING????

Quote:
Originally Posted by SailingJackson View Post
Similar recent thread talks much about trying to hack a trolling motor into a hydrogenerator. Reviewing that thread, it's clear that there are a lot of creative and resourcful people with interesting ideas. It's also clear that most of them don't understand the fluid dynamics involved and few of the ideas would have a chance of working.

Trolling motors are cheap things designed for lightweight use, running fishing boats around at slow speed. On the other hand the Torqeedo Electric Outboard is a much more powerful device and better designed for exposure in the marine environment.

Having been a product design engineer for 30 years, doing both mechanical and electrical design, I am highly suspect about the success of a hacked system. On the other hand, it certainly seems to me that the smart guys who designed Torqeedo could develop a similar version that could clamp on the transom as a hydrogenerator, with it's power electronics doing a controlled system charge. The same device could then be unclamped from the transom, clamped onto your dinghy. A quick prop change (yes towing is different than motoring), add the battery pack, and your ready to zip around the harbor. This seems a realistic goal for a product. It might cost 50% more than a regular Torqeedo, perhaps even twice. Even if it cost as much as a Watt & Sea generator, the Watt & Sea is only a generator. An outboard/generator would serve dual purpose for a typical cruiser.

Marine Industry: Are you listening?

G.J.
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  #28  
Old 01-31-2013
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Re: Towed Generator that We Really Need

Quote:
Originally Posted by bobmcgov View Post
with solar PV down to ~$1US per watt
Do you have a link to some panels for sale for ~$1/watt? Cheapest I've found is just under $3/watt for monocrystaline.
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  #29  
Old 01-31-2013
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Re: Towed Generator that We Really Need

I have two of these panels I plan on installing to a dodger I'm going to make and try to fit them as best I can... sew them onto the dodger...

Here are the specs:

Electrical Specifications

PVL-128 18ft x 15½ in.x 0.16 in. 17 lb.
Electrical Specification: PVL-128
Rated Power Pmax 128 Watts
Nominal Operating Voltage 24 Volts
Operating Voltage (Volts)Vmp 33.0 Volts
Operating Current (Amps) Imp 3.88 Amps
Open-Circuit Voltage (Volts) Voc 47.6 Volts
Short-Circuit Current (Amps) Isc 4.8 Amps
Series Fuse Rating (Amps) 8 Amps
Min. Blocking Diode 8 Amps

That's 256 watts total for both panels... not bad.... they are a little long and have to figure how to attach to the dodger but I'm sure I'll work it out...

These can be bought on Fleabay and they cost about $1 a watt or slightly higher... what is good about them is the flexibility and long wear since it must meet the current building codes... they are really tough and I have walked on them and so has my science kids when I used them for demonstration... very sturdy!

Nick
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  #30  
Old 01-31-2013
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Re: Towed Generator that We Really Need

I went to fleabay and searched for "solar", nothing came up. Got a link?



Quote:
Originally Posted by guitarguy56 View Post
I have two of these panels I plan on installing to a dodger I'm going to make and try to fit them as best I can... sew them onto the dodger...

Here are the specs:

Electrical Specifications

PVL-128 18ft x 15½ in.x 0.16 in. 17 lb.
Electrical Specification: PVL-128
Rated Power Pmax 128 Watts
Nominal Operating Voltage 24 Volts
Operating Voltage (Volts)Vmp 33.0 Volts
Operating Current (Amps) Imp 3.88 Amps
Open-Circuit Voltage (Volts) Voc 47.6 Volts
Short-Circuit Current (Amps) Isc 4.8 Amps
Series Fuse Rating (Amps) 8 Amps
Min. Blocking Diode 8 Amps

That's 256 watts total for both panels... not bad.... they are a little long and have to figure how to attach to the dodger but I'm sure I'll work it out...

These can be bought on Fleabay and they cost about $1 a watt or slightly higher... what is good about them is the flexibility and long wear since it must meet the current building codes... they are really tough and I have walked on them and so has my science kids when I used them for demonstration... very sturdy!

Nick
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