Hi all
First of all, a little background information. I have lived full time on a yacht for close to 15 years. I bought the present boat in Trinidad last summer after loosing the old one (and all my tools) in an accident. For much of this time I've been living truly off grid at anchor (not even a rope to land) with solar power augmented by infernal combustions. I'm a radio ham and understand about electricity and some basic electronics, but most of what I know about wind power comes from reading this forum the last week or so. You'll find more background information in the last thread I started here where we decided that the 12V outboard (trolling) motor I have probably wasn't going to be of much use as the generator for a wind turbine.
(http://www.fieldlines.com/story/2007/3/26/24711/3952)
I have now got my hands on a much more suitable generator than the trolling motor. It is the generator part (only) of a Duogen wind / water generator. The web site for the original product is here: http://www.duogen.co.uk/
I already had a 5' two blade rotor with a centrifugal air brake from a Four Winds wind generator, and with limited tools and funds, I will not be able to buy or make any other blades any time soon, so that is what I intend to use. When I get more tools together, I may decide to carve some better blades if the improvement is going to be worth the effort.
Here is what I've got:
The shaft diameter is a snug fit in the four winds hub even though the bearings described below would imply that the shaft is metric. I don't have calipers here. The hole seen through the end of the shaft could accommodate set screws for which there are threaded holes in the Four Winds hub. Approximately 1/4" of the inboard end of the hub would have to be cut away to get the shaft deep enough into the hub for the setscrews to line up with the hole in the shaft:
This is the open back of the generator with the visible magnet plate. I believe there is another inside the coils which can be seen around the edge of the plate. I have a document with disassembly instructions, but no drawings or photos of the inside.
The rectifier bridge was totally corroded out, so my intention is to bring the AC wiring (suitably beefed up, say #10 AWG) down to a control box inside the boat with a rectifier and a switch for shorting the windings to stop the generator.
Here the three wires coming out of the coils can be seen. Part of the stator can also be seen and it seems to be baked in epoxy.
I have not taken the generator apart any further than what you can see in the pictures yet, as I don't particularly want strong magnets around the boat until I have all parts available to reassemble it.
The bearings in the generator are shot, and I have a document from the manufacturers which describes how to take it apart to replace the bearings. The bearings are described by the manufacturer as "17 x 35 x 10mm radial shielded" and the shaft seal is 17 x 35 x 7. In the normal installation, the generator is driven by a long shaft down from the rotor, so there is no thrust load on the generator itself. The manufacturer says that in thrust applications they "fit an angular contact 17 x 35 x 10mm at the 'seal' end of the axle". I'm not sure what they are describing here. Is this a different bearing?
It's quite obvious that the attempts to waterproof the unit from the factory have failed miserably. My idea is to paint everything inside with epoxy primer to waterproof it and leave the back of the unit open to the elements. That would mean installing a seal on the inside of the inner bearing too, but that should not be too difficult. Or maybe better (waterproof) bearings could be used that would fit the available space. The turbine will be installed halfway up my mizzen mast, so it will be subject to rain and moist salty air, but not to direct saltwater. Suggestions would be welcome.
I would like to bring the three outputs from the stator down to a control box which would contain a rectifier bridge as well as a switch to short the windings to stop the rotor. If shorting all three windings dead would provide a too violent stop, I could short one first, then the other when the turbine slows down, or maybe dump to a dump load first to slow it and then short it. When I rotate the magnet plate by hand (with much rumbling of bearings) and short two of the windings, the generator slows and stops, but not very abruptly. I haven't had enough hands available to short it while I was still attempting to turn it. I'll try and use the trolling motor to spin it up one day to see what happens.
At a later date, I may install a small water heater on the boat and use that to dump any excess power from the turbine as well as my three 55W panels. I normally shower in cold water here in the tropics, but heating it a little might make any future female crew happier. The beauty of it is that one would be more likely to wish for a warm shower on a really windy day. The water heater will also be heated from the main engine cooling water of course, but I try to reduce my infernal combustions to the bare minimum.
At the moment, with three 55W panels I am generating slightly less that I am using, but it usually evens out with normal use of the engine in and out of harbour while cruising.
Any suggestions and advice would be welcome.
PS. I can post photos of the Four Winds rotor and centrifugal air brake later if anyone wants to see them.
PPS. My engine mounts failed on Friday night and I had to put into St. Vincent. That's what cruising is all about, repairing boats in exotic places! It's been raining for the past three days, so at least my water tank is full. Rainwater always feels nicer for a shower than tapwater. :)
Regards,
Owen Morgan
Yacht "Magic"
Young Island Cut, St. Vincent
A photo of my boat can be found here:
http://www.panoramio.com/photo/737793
Click here for my latest reported position:
http://www.findu.com/cgi-bin/winlink.cgi?call=LA7QZ
