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Entries in electrical (4)


hydrogenerator sea trials: completed

I've been reluctant to write about my hydrogenerator for two primary reasons. First, it's hardly a new idea. There are commercial versions (that cost a grand or two) and hundreds of sailors have built DIY versions for decades. Second, I hadn't tested my little creation yet so it seemed a little presumptuous to wax on about something that might not work at all. 

But today, halleluiah, I sea trailed the whole mess in the dinghy with great results.

Essentially you toss the black prop (connected to the stainless shaft there) into the water. It's connected by a shackle to some single braid line, and then goes taught, the other end of the line being secured to a shackle on an Electro-Craft E722 permanent magnet motor's axle.

At 300 RPMS, which seems to happen around ~4.3 knots, the motor makes about 12.5 volts. The faster it goes the more amperage and voltage it creates. I'm not worried about a voltage regulator because the amperage is low (about 5 amps at 12.5 volts, to maybe 12 amps at 90 volts), but to reach the upper threshold of voltage we would be doing double our hull speed so at that point over charging our batteries will be the least of my concerns. 

I had a local machine shop drill a hole through the generator's shaft so I could put a shackle through it.I only lost about 1/4 of a knot in my testing, so if I double that (to be a pessimist) and do some math it means a 20 day passage would now take 22 days. But that's 22 days of making 5 amps continually, which means we don't need to haul as much gasoline or diesel. And as anyone who's sailed downwind knows, it literally stinks to run the engine because the exhaust fumes blow into the cockpit and cabin. 

For the motor I had a few criteria. One, it had to be a permanent magnet motor. Two, it had to be fairly low horsepower because I wouldn't have a lot of rotational torque (generated by the prop) to work with. Three, it had to hit charging voltage (> 12.5 volts) at a low RPM. The Ametek models are definitely the most popular, but I re-read the specs on the Electro-Craft E722 and felt it would do the job as well if not better. Both of these motors were originally designed to spin large disk drives around and as such are frequently found on Ebay. The good news is that a lot of people are building wind generators these days, the bad news is that it's raised the price considerably on the motors. I was lucky and got mine for $50 but $100-$200 seems a bit more common.

The other thing I had the machine shop do was build a shaft for the prop with an eyelet on the end.For the prop I'm sure there are better options than what I got, but I was pressed for time and saw a $400 prop on sale at West Marine in San Diego for $40. I figured that was better than whatever else I'd be able to find so I tossed it in my checked baggage and called it good. 

I had a machine shop drill a hole through the motor shaft that would accept an 8mm shackle so I could secure that to a thimble in the tow line.

I also had the machine shop use a solid stainless rod, thread it, and pop a nyloc nut on for the prop. Also, they put an eyelet on the end that I could likewise shackle to a thimble on the end of the tow line.

When testing I was happy to see that the line doesn't kink at all: the rotational twist builds up in a few seconds and then starts happily spinning the motor. The drag on the prop causes the line (at least my single braid) to not kink, and any twist is transferred as kinetic energy to the motor's shaft. 

The only other thing you want to make sure to add is a blocking diode. Otherwise when there's more voltage in the batteries than the motor is making, either because the boat is slow or possibly because your solar panels are putting out a lot of juice, the motor will start consuming electricity rather than generating it, and you can watch the prop as it tries to spin itself away from your boat.

My machinist showing me the fastener assembly he built for the prop shaft.All in, rounding up, I spent $50 on the motor, $8 on a blocking diode, $40 on the prop, $100 at the machine shop, and $40 worth of line and thimbles. So that's $240 and possibly another $30 for a soft shackle to make a fairlead, call it $300 all in to hopefully have a sizeable heap of clean energy for our passages. I'll report back with more info but I've got high hopes that in addition to being quieter and more environmentally friendly it will also end up being cheaper as $300 worth of gas and diesel really doesn't go that far.  

Regarding fish eating it. Personally I think that's cruiser-folklore (a.k.a. "sea stories"). The stainless steel shaft is two feet long and it's 1/2" single braid which is pretty tough to slice unless you hack it to death in multiple attempts. I'm of the personal belief that the loss of towed props is due much more to common and less dramatic reasons like forgetting to mouse a shackle. Either way though, the electrical connections and line that secures the motor to the boat will be sufficient but intentionally the weakest link so that if a school-bus sized sea monster bites hard it wont rip the transom off.


magic: saltwater into freshwater

Water into wine? Pfft, who cares? Try turning seawater into freshwater: you know, something that people actually need. And now with the mystery of reverse osmosis desalination technology Rebel Heart is able to crank out magical freshwater that tastes so good you actually say "Damn, that's a nice glass of water."

Of course the Katadyn 40e costs roughly $4,000, took me three full days to install, needs daily maintenance, and requires yearly rebuilds. 

We opted for a watermaker because we have four people onboard now and in the Sea of Cortez it gets really frigging hot. On average we consume about five gallons of water a day and the Katadyn 40e can create that in about 4-5 hours. Water isn't available in many places we're headed to in the Sea of Cortez and even where it is, finding water suited for drinking and hauling it around in jugs gets lame really fast.

The watermaker world is divided into two major categories: low amp and small yield or big power and big yield. We opted for the smaller option for a few reasons.

First off, we don't run the engine that often and certainly not when just sitting at anchor having a nice day. It's loud, it heats up the boat, and diesels like to run under load not just sitting there with a wimpy watermaker attached.

Secondly, and this is primarily regarding the CruiseRO systems, although we have a Honda 2000 generator we also don't like running that all that often and certainly not underway when it's strapped down in a bag. Carrying gasoline is also annoying.

What we've noticed about our electrical profile here in the tropics is that we're routinely in absorption charge mode from our solar panels, meaning that roughly 5-10 amps is being kept back (lost) from the batteries. So flipping on the watermaker during that phase isn't going to cause any material net loss of amp hours.

But arguablly the biggest selling point to me regarding the Katadyn PowerSurvivor 40E was nothing the Katadyn company itself did. Enter Gary, the 40E owner's best friend. Gary did the following:


Any sailor knows that buying a piece of equipment is relatively simple. Installing, using, and maintaining it is a whole different ball of wax. Have such a broad knowledge base to work from on the latter issues was what convinced me. 

We ran it for a couple of days and marveled at the technology but after looking at the near constant oil slick and seeing particulates in the water I ran the membrane preservative through it. 



dropped $400 on some electrical stuff today

On the downside, $400 isn't exactly funny-money and I could think of things I'd rather spend it on. On the upside, $400 to prevent an electrical fire and help keep everything on the boat in top form is pretty cheap. 

Blue Sea Systems ACRFirst off, I dropped in a Blue Sea Systems ACR, or "Automatic Charging Relay". Its job is to join the battery banks when a charging current is present, and to isolate them otherwise (and when starting the engine). 

Before that I had a battery combiner that looked civil war vintage and although it's supposed to do the same thing it chewed up a lot of power just to keep itself alive and I couldn't find any form of documentation on it. The Blue Sea ACR comes well endorsed and has the notorious "forever" warranty as with most (all?) Blue Sea products.

My starting battery was past its usable life so I replaced it out with a Trojan 24SM-650. 

I also picked up two new battery switches. Rather than go with the classic on/off/both switch (which we're retaining for picking the starter's current), I really just want to be able to turn off each individual bank if needed.

Oh and let's not forget the new negative bus bar. The old one was corroded to hell and back and didn't have a lot of room left to grow. The new one is shiny and big enough for future expansion. 

And to make sure I don't melt the whole place down, there's a 150 ANL fuse block (also by Blue Sea). It's possible, I guess, to push more than 150 through the house bank. Running the windlass, broadcasting from an SSB, and energizing every other circuit might just do the trick. But chances are if 150 amps is passing through my house bank, there's a short and a fire is a couple of seconds away. 

Round all that out with 2/0 (pronounced "two ought") cables that I made myself with proper shrink sealing wraps and it's a pretty solid little setup. 

Eletrical to-do items:

  • Uninstall the old combiner and reclaim the space.
  • Get the new switches on a pretty panel in the front. 
  • Shrink wrap seal some of the older cables.
  • Get a proper fitting for the negative connection on the ACR, and a fuse to go along with it.
  • Lock the batteries down. I have boxes for *most* of them, but they're not strapped in tight enough to survive a knock down or rollover. 
  • Figure out what to do with the 1 amp trickle charge that's in addition to the "real" charge from my solar charge controller.



finally mounted the solar panels

Some painted cedarWe started off with two Kyocera 135 solar panels that we picked up from I did a lot of research, and the folks at were easily the least expensive and most knowledgeable. They even have some folks over there that know a lot about boats and a phone call to them for a few minutes can really help shed light (no pun intended) on solar energy.

Mounting solar panels on a sailboat is always tricky but I went with what I think is a pretty straight forward set up. Out on our boomkin (the thing that sticks over the transom) we have some big teak rails, and stainless steel railing around that. 

A quick trip to Home Depot for some cedar, I cut two boards that are as as long as the panels themselves are wide. Two coats of Interlux Pre-Kote primer and two coats of Interlux Brightside: not exactly the perfect paint job but we're not doing the Sistine Chapel here. Just keeping two pieces of wood from rotting or getting termites.

AFI Fast Mount Rail Clamp

I picked up two AFI Fast Mount Rail Clamps (per panel). Gemini makes a model as well that you might want to consider. The AFI models are made of High Density Polyethylene (HDPE) which from what I see has a very high UV resistance.

I went about installing the rail clamps to the boards, and then the boards to the solar panel frames themselves. I used a decent amount of BoatLife Life Caulk to keep the water out of the wood, and some nylon washers to keep the stainless steel away from the aluminum (to prevent galvanic corrosion). 

Clamps mounted, ready to mount to panels#10 panhead machine screws formed the bulk of the hardware used in the fasteners. 

I still need to mount some feet to the bottom of the panels in order "wing" them up and bring the surface area more horizontal, but for now I just wanted to get them off the deck and in their new home arrangement. Also, I still need to wire them up and move the BBQ grill to its new home. Every project creates three more, etc, etc.

MountedIn this arrangement the panels should be able to rotate up about thirty or forty degrees (or even over ninety), or fold flat. The only thing I'm not terribly excited about is the sheer size of them: a KC135 solar panel is five feet tall, and putting big ass panels up on a boat breaks up the beauty of the boat a bit.

As I said above one of the next adventures is going to be wiring them. I picked up a BZ M25 solar charge controller, and I can't wait to see both panels pumping out their rated 7.6 amps (for a total of ~15 amps) during the day time. 

I had a solar panel on my last boat and they're common enough in the maritime world but there's still a neat joy that comes with watching you get free electricity from the sun to run your appliances.