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Towed generators
Any recommendations?
Gordon |
Towed generators
On Jan 4, 8:14*pm, Gordon wrote:
* *Any recommendations? * Gordon Hi, include me in the interested readers. Of most importance, relable brands, minimum water speed to produce N amps. Im wondering if I could just throw one over boad while at anchor with a running tide? Tides run at 1~4 knots here and would be great to get some juice.... that is when im not holding on during those 93 mph gusts.... Been haveing a few storms over hear last couple days. Bob |
Towed generators
Gordon wrote:
Any recommendations? Gordon Some of the older wind generators used to have a towed sea generator as an alternative attachment. I haven't a clue as to their effectiveness. Dennis. |
Towed generators
On Fri, 04 Jan 2008 20:14:09 -0800, Gordon wrote:
Any recommendations? Gordon Think about it this way. If the generator is 100% efficient, then to generate 746 watts, one horsepower must be provided. Imagine a dinghy with a one hp engine pulling your boat backwards and you get a sense of practicality. In practice, two or three hp is probably closer to what the effect might be. So there is plainly an upper limit to the amount of power a towed generator can realistically provide to a small sailboat. Chuck S/V Sans Serif ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
Towed generators
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Towed generators
wrote in message ... On Fri, 04 Jan 2008 20:14:09 -0800, Gordon wrote: Any recommendations? Gordon Think about it this way. If the generator is 100% efficient, then to generate 746 watts, one horsepower must be provided. Imagine a dinghy with a one hp engine pulling your boat backwards and you get a sense of practicality. In practice, two or three hp is probably closer to what the effect might be. So there is plainly an upper limit to the amount of power a towed generator can realistically provide to a small sailboat. Chuck S/V Sans Serif ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- In the late seventy Yves Gélinas "Jean-du-Sud around the World" used a towed generator. The electrical power produced was mainly used to communicate on his short wave radio. Every day he radioed his position. Then all of a sudden no more communication were transmitted by him. Later it was learned that the impeller on his towed generator had been chewed to pieces. When he returned home I talked to him and he stated that the sharks made a meal of the generator impeller. He also mentioned that the life expectancy of an impeller is in relation with which region of the globe you are sailing. |
Towed generators
Roger ... Yves sailed and I think still sails ... an Alberg 30.
Reading his logs is like standing on a cliff, waiting for the end, but always somehow, someway,, the end never gets ya. === "Roger Long" wrote in message ... wrote So there is plainly an upper limit to the amount of power a towed generator can realistically provide to a small sailboat. Yes, but Yves who builds the Cape Horn steering gears used one very successfully on his circumnavigation in a Bristol 30. He even built a new rotor from scratch when a shark ate the first one. Impressive bit of work under the circumstances and with materials at hand. If you haven't seen his video, you really should. I generally find sailing videos pretty boring but his is great. -- Roger Long |
Towed generators
In article , Roger Long wrote:
If you haven't seen his video, you really should. I generally find sailing videos pretty boring but his is great. Is this a YouTube video, or one to rent/buy or what? Does it have a name? Justin. -- Justin C, by the sea. |
Towed generators
In article , wrote:
In the late seventy Yves Gélinas "Jean-du-Sud around the World" used a towed generator. The electrical power produced was mainly used to communicate on his short wave radio. Every day he radioed his position. Then all of a sudden no more communication were transmitted by him. Later it was learned that the impeller on his towed generator had been chewed to pieces. When he returned home I talked to him and he stated that the sharks made a meal of the generator impeller. He also mentioned that the life expectancy of an impeller is in relation with which region of the globe you are sailing. Unless the impeller is perfectly balanced there'll be some 'wobble' and therefore vibration. I wonder if this is similar to the 'creature in destress' vibrations that sharks pick up? ... maybe someone could patent this as a lure for shark fishermen! Justin. -- Justin C, by the sea. |
Towed generators
Towed generators are practical for working sailboats. It is free
energy and they have usable output. BUT. 1. Most sail boats spend over 95% of their time at a dock or at anchor. The towed generator is useless then. 2. If you are motoring it is an extremely expensive and inefficient way of generating power. Put an extra alternator on your engine and gain a 500% increase in efficiency and a fraction of the installation and maintenance cost. |
Towed generators
wrote in message ... On Fri, 04 Jan 2008 20:14:09 -0800, Gordon wrote: Any recommendations? Gordon Think about it this way. If the generator is 100% efficient, then to generate 746 watts, one horsepower must be provided. Imagine a dinghy with a one hp engine pulling your boat backwards and you get a sense of practicality. In practice, two or three hp is probably closer to what the effect might be. So there is plainly an upper limit to the amount of power a towed generator can realistically provide to a small sailboat. Small sailboat? So, probably a 12 volt battery.. 746 watts is 62 amps at 12 volts-far too much for your battery. Certainly there is an upper limit to the power you can get, but there should be no problem in getting quite enough to power up anything you have aboard a small sailboat. |
Towed generators
Gordon wrote in news:13nu10ihddb3o01
@corp.supernews.com: Any recommendations? Gordon http://www.brownmarine.com/tg09.htm Larry -- Everybody sitting in the dark at the anchorage will be your friend! |
Towed generators
"Edgar" wrote in
: Small sailboat? So, probably a 12 volt battery.. 746 watts is 62 amps at 12 volts-far too much for your battery. Certainly there is an upper limit to the power you can get, but there should be no problem in getting quite enough to power up anything you have aboard a small sailboat. Lionheart, my friend Geoffrey's Amel Sharki 41 has a Perkins 4-108 with freewheeling hydraulic transmission and a shaft alternator that produces about 25A of 12V power at 7 knots, about as fast as she'll go. It still produces 15A at 6 knots, but drops off rapidly below 5 knots as the load stalls it. There's a large wheel on the shaft about 6" behind the transmission turning about a 3" wheel on the specially-designed-to-turn- slowly alternator, which I think Motorola made. It's not self-exciting and requires 12V, switched by a key in the control panel where the ammeter shows you how we're doing. This key is on a welded ring with the engine key and locks itself into the panel until you turn it off. This prevents even the stupidest amoung us from running the shaft alternator when the engine is running, which the instructions say will destroy it. The key to all this is that transmission that allows the shaft to freewheel without destroying the transmission. Larry -- Next time some broker tells you what a great investment he's selling, ask him about Rhodium, a shiny metal used in Catalytic Converters. Jan 1st 2004 2005 2006 2007 2008 Rhodium $452 $1341 $3006 $5339 $6775 PER OUNCE! How much longer can we pay for new cars at this rate? Feb '97 it was $182/oz |
Towed generators
Gordon,
I have built into my 60' sloop a prop shaft with pressure fed oil bearings and it drives a Sperry Marine rig that was designed to power winches on lobster boats. The Sperry Vickers variable volume hydraulic pump drives a fixed displacement hydraulic motor on the end of an Onen 6 KW 2 pole alternator. The pump will handle input speeds of 1100 to 4400 rpm. The unit adjusts the pump volume automatically while monitoring alternator output frequency and will hold the frequency within 3 Hz. I use a toothed belt to drive a gearbox and from the gearbox I drive the Vickers pump. At the most inefficient speed the unit draws 22 HP at 6 KW. The plan is to use the trailed prop to drive this rig. The 3 bladed prop I am using is 70 CM in diameter with a 26" pitch and a 70% BAR. It has been sized to drive the boat. I cannot tell you if it works, I have not tried it yet. When designing this, I could find no data on the efficiency of props in drag mode. To my knowledge, no study has even been performed and I asked everywhere I could think of. I expect when in use the boat will slow somewhat, but how much only time will tell. The unit will antomatically drop the load, if speed drops below 1100 rpm. I am sure I will have to do some tuning, but I believe it will work or I would not have spent all the time and money to build it. Steve "Gordon" wrote in message ... Any recommendations? Gordon |
Towed generators
Edgar wrote:
wrote in message ... On Fri, 04 Jan 2008 20:14:09 -0800, Gordon wrote: Any recommendations? Gordon Think about it this way. If the generator is 100% efficient, then to generate 746 watts, one horsepower must be provided. Imagine a dinghy with a one hp engine pulling your boat backwards and you get a sense of practicality. In practice, two or three hp is probably closer to what the effect might be. So there is plainly an upper limit to the amount of power a towed generator can realistically provide to a small sailboat. Small sailboat? So, probably a 12 volt battery.. 746 watts is 62 amps at 12 volts-far too much for your battery. Certainly there is an upper limit to the power you can get, but there should be no problem in getting quite enough to power up anything you have aboard a small sailboat. Maybe once upon a time? But these days.... |
Towed generators
...Small sailboat? So, probably a 12 volt battery..
746 watts is 62 amps at 12 volts-far too much for your battery... Maybe once upon a time? But these days.... The folks I've talked to with towed generators love them and claim they get about an amp per knot and it takes about half a knot off their boat speed... I suspect they are being generous. Nevertheless, if you need 60 amps all the time you really need a genset. Even with a 12 volt fridge and autopilot 5-6 amps should pretty much keep up with demand. -- Tom. |
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