Just Some Notes for Now:
First off I’ll talk about the metal parts, the parts described in the crumpled mechanical drawing. I found it just where I remember leaving it (isn’t it great when that happens), in the glove compartment of my little sports car. Sorry if the photo is hard to read. In short it consists of a spindle, hub and disks. The spindle is made of aluminum in my case as I welded/bolted it to a aluminum mount. The hub and disks are made of steel. I needed to use steel in the disks to move the magnetic flux on the back side of the Neodymium poles. The front disk is welded to the hub, the back disk will be attached with 3/8 stainless threaded rod and nuts. The spindle carries the hub with a standard trailer bearing set, seal included. I chose these because they are easily sourced anywhere, cheap and have plenty of capacity. Ball bearings would be lower drag but the needle bearings have really not been a problem in my experience.
You would change the back side of the spindle to attach to whatever kind of mount you choose to use and I imagine you will make your spindle of stainless as it is exposed to the elements where paint won’t stick near the seal and you will not be using an aluminum mount.Since this drawing I made a big improvement. This will probably need another photo or phone call but I will take a shot of describing my change. As drawn the hub attached with an e-clip. After my Eastern Caribbean trip I changed this because it was hard to keep everything tight but not too tight (shims were a bid idea), and because the big e-clip was a pain to put on. I just cut the spindle shorter and made a disk of aluminum that I screwed onto the end of the spindle once the bearings were installed. I used one 1/4 to flathead machine screw in the center and three smaller flathead screws around the outside if that with soft locktight to hold it all together. Works quite well. (only took about 5 tries to come up with something easy that works and fits the space)*If I was to make this all over again I would think seriously about making the disks and hub out of aluminum. I have decided that this would work if the magnets were oriented in a halbach array. But I bet you will prefer steel since you won’t be taking this thing down and weight aloft isn’t a big concern with a big wide boat like yours.Before you start cutting steel you really need to decide on the size of the disks. There are advantages to having a larger diameter disk set to hold the magnets out further. Even one inch larger would give a lot more room for the windings. I was limited by the size of the lathe I had available.——————————————–Now for the fun parts, how the alternator works. You will be epoxy-ing magnets onto the disks so that you have alternating north and south poles. Four pieces of stainless all-thread will be screwed into the front hub and locked by stainless nuts. Enough threaded rod will protrude forward to allow the blades to be attached and enough will protrude back to mount the back magnet disk. The back disk is mounted between stainless nuts on the all-thread. BE VERY CAREFUL with assembly as the magnets in this array are extremely strong. I did the math once and I think if mine came together it would take 2000 lbs to dead pull them apart. Don’t get pinched!Even if you choose to use steel disks I would think about using a hulbach array arrangement for my magnets. It’s cool (I’ve used it elsewhere) and there are so many choices with size of magnets now. A combination of wedges and plates would be interesting to work with, but I haven’t tried this in an alternator yet.Between the two disks you mount your stator. You adjust the nuts to give yourself the clearance you want between the magnets and stator surface. You can also de-rate the alternator by increasing this gap (thus lowering the magnetic field passing through the stators coils) if you want less torque taken off your blades.The number of magnet poles and stator coils are flexible but should be in the ration of 4 to 3. In my case I have 16 poles and 12 coils. The poles alternate between north up and north down. The coils are broken into three phases and alternate between phases. So the stator is arranged with a phase 1 coil, followed by a phase 2 coil, followed by a phase 3 coil and then back to 1…. It seems strange but this orientation makes magic and you end up with a north pole going over each coil set at exactly 120 (in ac waveform) degrees apart and nice three phase comes out that would make Tesla a happy man.The stator needs to be held firmly to the mount. I used my trusty threaded rod and nut approach again. That is what the four threaded rods around the outside in the photo are all about.I made my stator by winding the poles around wooden cores. Don’t use iron cores, the cogging isn’t worth the gain in power and makes balancing the blade a horror. I put together a little machine in literally 15 minutes made out of scrap wood to do the windings. Nothing fancy is needed. I then put them in place in a mold I make from something really flat. Last I used painted particle board and loads of wax, works well and is easy. I bring the wires to the outside of the mold and solder them to brass screws that become my contacts. I temporarily screw the coils exactly in place and cast them half thickness in thickened polyester. Once that sets up I remove the screws and add enough polyester to make my stator. I usually put a layer of fiberglass over both outside surfaces. See photo for a very used red stator.I make my blades without your c&c rig so I won’t go into detail as you have better options. But in short I have a method that works with just a hand saw and angle grinder. I once made a blade set for someone in Grenada on the stern of a sailboat. The spreadsheet has all the information you need but I bet it’s indecipherable. Call me. In short it’s telling you how wide the blade should be at each station, how thick at each station and what angle (measured in mm of drop to the trailing edge) at each station. After spending hours on airfoil design I found a NASA page that showed that a simple top curve with the max thickness 1/3 back from the leading edge had great lift/drag ratios and have always finished them that way.The other spreadsheet is best used once you have your magnets mounted. You put a small coil of wire between the magnets, hook them to an ac meter and spin them at a known RPM (that’s what I’m doing in the photo). You are looking for how many volts per turn per rpm your unit generates at a given gap setting. Then you slip that number into the spreadsheet and let it help you choose how many turns you need and of what gage wire. If you were to make your disks a bit larger you would find you can use larger gage wire and have a smaller gap for a given number of turns. All these things can make more power with fewer losses in heat. More turns tend to have more resistance and make less power at high RPMs. Too many turns can take more torque off the blade at low RPMs and stall the unit keeping it from ever spinning fast enough to make real power. This spread sheet is great at getting all this balanced before you build stators.I will leave the mount up to you. You need to allow the wind generator to move with the wind at least 45 degrees each side of forward, more if you want to use it while sailing or when not anchored into the wind. A tail is probably the best way to do that. I wouldn’t get fancy with a movable tail system that feathers the blades out of the wind because a boat moves so much. That approach really needs a mounting pole fixed to the earth in my opinion. I think you will be well served with just shorting the three phase lines before they go into the rectifier as a break. You could also cobble some kind of mechanical break of course. From a quick look at your boat I think mounting it above the mizzen would be a good candidate.It’s been fun thinking about all this again. I forgot how much was involved. I’m sure this document is like drinking from a fire hose. And with my sloppy presentation it’s like that fire hose has a wide nozzle on it. Sorry. But as I said we can chat on the phone. And I’d be very happy to help you with your design once you have an idea what size blade you want to swing and how much power you need.Here are the spreadsheets that help one design the blade and alternator windings.
more coming the rest is on my computer. I’ll send the Excel files and a discussion later. This is a photo of my mech. Drawing for the steel parts.A few quick ideas:I don’t see any problem with a fixed mount. Looking at your sail plane I expect you would want it on the front the the mizzen. You are right, you will need to allow the unit to move with a tail. The yacht just doesn’t move fast enough at anchor with wind changes for a wind generator to function, not to mention the effects of current. For you I would suggest a three blade unit. They are smoother and you won’t be taking yours down to store. I over build my stators and with the powerful magnets we have available now days there is really no reason to lock one down in a storm. I have a beefy relay that closes on the three phase lines coming down from the generator when my battery voltage goes up or I just want to stop the unit. With the three phase wires shorted the blade slows to a crawl in seconds and can never do more then maybe 30 rpm in the strongest wind.Since this will be a DIY project you can tailor it to your needs. I developed mine to make power in low winds. For example, mine starts making power in about 8 knots of wind. I choose this accepting the sacrifice of making more power in high winds. It would be best if you had some idea of how much power you wanted from this piece of kit and at what wind speed you wanted it to be effective in. You could always swap stators to a high power unit for the trades and a low wind speed unit for the higher latitudes but that would be a pain with it up so high. And you should decide how much power you want it to make to be worth effort and we can choose blade diameter and such from there.This could be a cool project and one that I think loads of people in internet land would find interesting but it might not be the best choice for you. You have loads of real estate on that house top for solar panels and from what I hear on your channel you might end up being a generator boat. Putting alternative power generation on a boat that will need to run a genny a couple of hours a day may just become waste of money and effort. I went the other way and have literally gone six months without starting an internal combustion engine on my boat, using the wind and sun for all my needs (except cooking). It’s handy to have the boat be able to take care of herself but I’d hate to steer you into spending your valuable time on a project you won’t really use when you get out there. Just a thought, one of the things I’ve learned in the last 18,000 ocean miles is everyone cruises differently.Clarksv/Temptress