Electric Propulsion

[SunDevil]

My current idea is to get a 'smallish' 30 foot catamaran and create a bimini out of solar panels (I have 8 already at my house). If I can generate 1500-1800 watts when the summer sun is out (and I will be migrating north and south throughout the year to follow 'summer'), I would hope to be able to use the motor a little to move faster during the day when needed. In addition to recharging batteries and other electrical needs (hot water, cooking, blender, Air Con?) when at anchor. The batteries would be used to provide additional full power for short periods of time, or if in trouble at night time.

[noelex 77]

Originally Posted by SunDevil

My current idea is to get a 'smallish' 30 foot catamaran and create a bimini out of solar panels (I have 8 already at my house). If I can generate 1500-1800 watts when the summer sun is out (and I will be migrating north and south throughout the year to follow 'summer'), I would hope to be able to use the motor a little to move faster during the day when needed. In addition to recharging batteries and other electrical needs (hot water, cooking, blender, Air Con?) when at anchor. The batteries would be used to provide additional full power for short periods of time, or if in trouble at night time.

Unfortunately the idea you have is not going to work in the form you have stated it here.
Do the sums for energy in and out. This will show you what you can achieve with solar. If you forget about the hot water, cooking, blender and Air Con. Limited electric propulsion should be feasible.

[SunDevil]

I should have stated that they would only be used one at a time.

[noelex 77]

Originally Posted by SunDevil

I should have stated that they would only be used one at a time.

You still have to generate the power you use (even a bit more)

[SunDevil]

Having a refrigerator would be nice, but would require power around the clock. That would be the tough one.

For hot water, I might consider using black tubing and letting the Sun heat it up. I will try and keep the outside temp in the 60s or higher, so really hot water isn't critical. And something like this might work for short showers. EEMAX Electric Instantaneous Water Heaters at West Marine

Cooking would only take 30-60 minutes at most, and the 1500 Watts of solar panels should take care of providing power.

Computer/TV - My laptop uses 18 watts of power when it is on. Chart plotter, LED lights, VHF radio and AIS shouldn't require much power.

There are battery powered blenders or using a regular AC blender doesn't use that much power. Speaking of that, running an ice-maker and water filter while at anchor would be nice too.

I am a little more concerned about the 500 lbs of weight, plus the 500? lbs of Lithium Iron Phosphate batteries (or if there are inexpensive solid state ones by the time I get around to this). The boat might be a little heavier, but the motor can be run at a slow to half speed during a sunny day. I am hoping to find a lot of sunny days...

[JRM]

Originally Posted by noelex 77

Unfortunately the idea you have is not going to work in the form you have stated it here.
Do the sums for energy in and out. This will show you what you can achieve with solar. If you forget about the hot water, cooking, blender and Air Con. Limited electric propulsion should be feasible.

Let's do a bit of basic math. Assume we're going to use Kyocera 235W panels, as they're really popular right now. They're 65" by 39". This is a 30'er, so let's set them up lengthwise for the bimini, and we'll forget about any backstay, shading from the boom, or any real world details. These are perfect widgets. Only three of these panels would make a bimini that is 5.5' x 9.3'. That's a lot of overhang... Maybe we'll turn them end on and have the bimini run almost a third the length of your boat. Whatever...

So our three panels put out a max of 705 watts. It's a perfect world, so we'll magic up an MPPT controller with 100% efficiency to go along with our new magic "no-loss" wire and connectors resulting in the whole system having no losses. The sun will instantly rise to directly overhead and remain there for 12 hours per day, when it will instantly set. We'll call it 8.46 KWh gathered per day. Sounds like a lot. And it would be if it were just house load.

But you mention an electric motor. Coincedently, I happen to have converted my 30' auxiliary sailboat to electric power, so I have a decent idea about what it takes to push one around. Granted, mine is a monohull, but since I couldn't fit a cat in my slip, it'll have to do.

If I motor at 4 knots, I'm burning around 2 KW in the ocean on average. That drops to about 750W for 3 knots or so. I can add about a knot and change of boat speed when motor sailing for about 300 W (give or take). Given your perfect array on my boat, I could go three knots for the twelve hours the sun was up if I used nothing else. The guys over at propulsion marine built themselves a fully articulated array onto a Catalina 30 which allows them to run between 2.5-3 knots all day long. I've watched the project progress. It's cool, but you don't want to do that engineering from scratch...

Solar is great for house loads, but don't count on it for propulsion. If I toss a pair of 185 W panels on my bimini (at 35 lbs. each I won't sail with them up there), I can realistically recover the energy required if I had to motor completely from the harbor to the anchorage at Pelican's (about 24 miles) in seven days of good sun. I understand that the idea sounds great, but in real terms, it just isn't there yet.

I wish I had better news, because that would mean that I was solar sailing myself. I've sunk a good chunk of both time and money into my setup, and I can tell you from experience that it just isn't there if you want to motor a lot. For that you need to go hybrid, or to be honest, stick with an ICE. Nothing beats gas/diesel for energy storage density.

JRM

-- the rule of thumb we like to bandy about is that the a large but still practical battery bank is generally about the usable energy stored in a single gallon of diesel. If you use less than that per trip, electric will change your life.

[deckofficer]

I have just read 3/4's the way through this thread, and here's my two cents worth and I'll admit that is all it's worth.

Whereas fast cat 435 might have an agenda, I'm on board with that.

Dick Pluta knows what he's talking about. I think I have a similar background, but if readers of this thread are wondering whose advice they should follow, that would be Dick Pluta.

daddle, though he has excellent taste in boats with the Santa Cruz 50, he just doesn't understand electric motors, horsepower which is of course a unit of work, torque and angular twisting force, or not much else of anything he said on this thread. I'm a fairly new member to this forum, this is the first time I've blasted anybody, and I already regret doing that to daddle, but this form of propulsion is very important to understand. The best transference of energy to the water medium is through the largest propeller with the greatest pitch. In my line of work, my diesel's top RPM is 118, direct drive. That is aboard the container ships I have served on. A much more efficient use of the energy stored in a gallon of diesel is to have the diesel engine running in its ideal RPM, and using electric motors for drive. Later in my Merchant Marine career, I served as captain and BCO on dynamically positioned oil drilling rigs. The last rig I served on had seven GEN sets, generating 32 MW. Hotel and drilling loads never exceeded 1 MW. Fighting environmental forces to stay over the wellhead could take approaching 30 MW of electricity. Nothing was more efficient than running the necessary number of GEN sets at their fixed RPM supplying AC to six 5000 hp electric thrusters. On a catamaran it is best to keep weight towards the center and that alone makes a diesel electric hybrid propulsion system desirable. But there are many more advantages than just this, one of course is the efficiency of said system, two, regeneration under sail, the potentials here have not even been tapped. Electronic pulse width modulated controllers have the ability using nothing more than a 0 to 5K ohm pot for controlling regenerated energy. I think daddle even questions the efficiency of an electric motor at low speeds. The RPMs required to push your boat at just 4 kts is so low on the torque curve of a diesel motor that you are truly stuck with horrible efficiencies. Not so on the electric motor, it doesn't care what RPM it runs at. How in the world do you think diesel locomotives get all that mass from a standstill rolling down the track? Because it's diesel electric. Somebody else touched on the fact of the instant response you get during maneuvering when swinging a big prop with a big pitch being driven by an electric motor. If you haven't experienced this, you need to reserve comments.

I'll reiterate, if you're confused, just read what Dick Pluta wrote and you will understand things. daddle, sorry to attack you, but your passing bad information. On this forum it is not about egos, but rather some reliable information to be shared.

[JayCall]

I spent a lot of time and effort working with a noted naval architect and an engineer to design a diesel electric trawler in the 57-65 foot range. This got all the way to a completed design with a model for tank testing. I will echo a lot of what Deck Officer said. However, what we learned was interesting. The fuel efficiencies some have claimed for a hybrid system were just not there, at least not a difference sufficient enough to justify the added cost. We found about a 5% fuel uage difference at best. However, there were several advantages in the type boat we were looking at that had more to do with flexibility, some initial cost differences, and ongoing maintenance costs that could make a hybrid sytem attractive. In a trawler, where weight is not much of an issue, we designed the entire electrical system to be battery driven, through inverters of 110/220V where needed, so having a huge battery bank was a requirement. We also designed the system so that both props ran off one engine and generator. This allowed us to place the engine anywhere in the engine room and for the engine to be completely sound shielded. We designed to only have a single generator to recharge the batteries and serve as a second source of power to the electic drive motors. The chief advantage here was the ability to reduce the size of the engine room, and thus oncrease living space by about 25%. The only real fuel related efficiency was the ability to have the drive diesel run at an optimum RPM constantly. The fuel savings from this were minimal, the 5% mentioned, but the wear and tear and miantenance on the engine was less. this sytem allowed us to design a much simpler engine room and drive system, only the 2 diesels rather than four (two drive and a large and small generator) common on that size trawler.

Ultimately we did not build as the cost of a one-off boat of this type was prohibitive at least for me. Nonetheless, in a production setting, a hybrid system is hardly more expensive that a traditional diesel driven system.

You can also note that this is not cutting edge technology, Siemens has been building diesel electric systems since 1895. Everything is pretty much off the shelf.

[daddle]

Originally Posted by deckofficer

this is the first time I've blasted anybody, and I already regret doing that to daddle, but this form of propulsion is very important to understand.

Deckofficer, that is rather lightweight blasting. No problem. No offense. As a retired engineer (electronics, robotics, etc) I'd prefer a proper technical takedown to just unsubstantiated opinion-based "blasting". My intent was not to pooh-pooh electric motors. It was a hopeless attempt to counter the religious fervor, outright errors, and marketing-driven hype of some of our over-eager electric propulsion proponents.

Again, I'm pro-electric propulsion too. But a realist.

[deckofficer]

daddle,

Your a true gentleman, more so than me. I certainly should've been more specific, stating that at very slow speeds, i.e. 4 kn or less, where the diesel is at an RPM that rears it's ugly inefficient head, the electric motor shines. I personally think it is nice to have redundant systems and with the diesel electric and battery bank, if the diesel is out of commission, and you are in currents and are having to maneuver, it is nice to still be able to do so on that battery bank. Reduce the speed, and that battery bank will take you a long way. Something that really hasn't been researched too much as of yet, is the possibility of using the large diameter and pitch props as a sea anchor or drogue. In a strong regenerative mode I would think that not only will it help keep your bow pointed in the right direction as you come off the wavecrest but just might keep your speed in check on the downward run.

Again though I commend you on the choice of the Santa Cruz 50, a really great race boat that if not overloaded makes a wonderfully fast cruiser. I used to have an old Cal 40, it wasn't 1/2 the boat that Santa Cruz 50 is.

[deckofficer]

Originally Posted by Alberto

I started evaluating electric over ten years ago when in need to repower my previous sailboat. At the time nobody had solid information on range, reliability, etc. I was not convinced by Solomon's Technologies at the time. ASMO Marine was just starting up, I exchanged a great deal of information with its owner and I was really impressed by him and his products (which got better over time), but nobody would anticipate (even guess) expected range. In the meantime we decided to sell the boat and I installed a new diesel to make it more attractive (it worked, sold in two days).

After 10 years enduring a Volvo MD2B in our "new" boat, last year we decided to repower with electric. The electric boats group at Yahoo was a fantastic source of information. I devoted a long time to research all the options. In the end I decided to design and build my own system (some pictures in the member's galleries). Several reasons for this, among them the fact that what you buy as a "system" is only a part of the whole installation, you need to select the batteries and charger, their location, controls, meters, etc.

The system as designed provides lots of flexibility in case I have to make changes based on real performance. For instance, changing gear ratio is easy, as well as system voltage, etc. Fortunately, none of this was necessary, the system worked flawlessly since day one. After over a year we never regretted the conversion, we would never consider installing a diesel again on this boat...

As for the system: brushed MARS (ETEK RS) motor, Kelly controller (great product, it allows all sorts of programming by the user, and excellent customer support, they revised my design over and over), 72V system (AGM batteries), synchronous gears (2.4:1 ratio), QuickCharge charger (it charges each battery independently, with several available charge profiles), heavy duty solenoid, etc. I adapted the original throttle control and built a new instrument panel. The engine room houses everything except the battery charger, and also serves as a new, large storage compartment given the smaller size of the system (more storage where the fuel tank was located). My calculation is that the whole system weights 150 lbs less than the diesel. Total cost was less that $4,200 (including some spares and miscellaneous items like a DC to DC converter for eventual house use, which I have yet to install).

What we love:

• Instant power.
• Quiet. Unbelievably quiet at low speed, a little humming at higher speeds.
• No diesel fumes/smell/smoke. No vibration.
• No maintenance (at some point, some years down the road, I'll have to replace brushes I guess). No more oil/filter changes, no more winterization, no more clogged fuel filters, no more bleeding lines, no more servicing injectors...
• Zero operating cost (we charge the batteries at the marina). No more stops at fuel docks.
• So far, completely reliable
• And... the looks of other people when we enter anchorages. We literally "glide" by, the boat is moving in complete silence and people already at anchor can listen to our music, eventually our conversation (as we can listen to theirs), and they stare at us because something is odd about this picture. It is so imprinted that they don't realize what is missing: engine noise! We love their stares

Finally, range. We kept the old two blade propeller. It was inefficient with the diesel and should have been worse with electric, as three blades are recommended, but it has worked fine (to add insult to injury, the bottom has not been painted for a long, long time, which has a clear impact on performance). Last year we motored 13 nm at 3.6 knots in calm conditions and when arriving at the marina still had plenty of battery left. We motored 4 miles at 4.2-4.6 knots against 18 knot winds for over an hour and again, plenty of battery left when arriving. Consumption when day sailing (leaving/entering the marina, eventually anchoring) is minimal, and the batteries recharge immediately. Charging time when fully depleted (to about 40%) is between 8 and 10 hours. I guess that with a clean bottom and prop and low speed (around 2.5 knots) in calm conditions we could get easily over 20-25 nm (I'll confirm this soon, after hauling out for painting).

For the future: a portable generator for peace of mind while cruising for several days. I guess we will use it to recharge the house bank more than anything else.

We loved our boat. Now even more.

Alberto

When I said "I've read 3/4 of this thread" I don't know how I missed this post. The Etek is a crazy powerful PM brushed motor that weighs all of 23 lbs. Can deal with 300 amps for one minute, 100 amps cont. If your running 48 volts, that works out to 6.4 hp cont., 19.3 hp for one minute. Lower in the real world because of motor and controller efficiency, not to mention the Puerket effect if using your battery bank. If you never pull more than 100 amps, you won't be replacing brushes in your life time. I have pushed this motor to 700 amps for 5 second blasts, and I'm here to tell you, having close to 40 hp in a 23 lb package propelling a 100 lb scooter, well if it was a bronco in the rodeo it would have a perfect record. I've allowed 5 friends/family to try and ride this death trap of a scooter, and as it stands, 5 out of 5 on their rear ends, even with a thorough pre-flight about all torque available at zero rpm. I have run it against my Corvette, and up to 40 mph is ahead of it. The controller in my pictures was only a 300 amp unit, the 700 amp heat sinked monster took up the entire rear deck and was "hanging 10" over the edge. Can't find any pictures with that controller. I used to compete, if you can call it that, against the gasser scooters. They were kind enough to invite me to their events, and what do I do in return? Walk off with their hardware. The last race I participated in, they decided to handicap me, so the race was an open road race on historic Route 66 in Arizona. The above owner of the Etek drive for his boat will have no trouble digesting this about his motor, but I knew that small 23 lb motor could still run fast hauling its 100 lb weight, my 240 lbs PLUS TOW a 500 lb battery trailer.






Just an aside, I'm an early adopter, this is my Smart Car Electric knock-off.

[deckofficer]

I hope I don't kill this thread by boring most of you to tears, but after re-reading it, I'm raring to go.

My current project is to convert the dinghy to electric. First off I need to purchase a new dinghy because my current one has too much wetted surface. When I was at the California Maritime Academy I did my thesis on minimum wetted surface vessels and know from that research that for this dinghy project to fly, it too needs a minimum wetted surface. Thankfully, there are many catamaran style dinghies with rigid bottoms, air entrapment hulls currently on the market. I am dragging my feet a bit on this project because lithium ion batteries are coming down in price and I'm not a fan of paying $6000 for a 96 volt, 160 amp hour, 15.3 kWh battery bank. I have picked up a 50 horsepower lower drive outboard less the engine and because prop selection for this size outboard is limited in pitch, I'll have to gear up the motor to the shaft to offset the 1.85 to 1 ratio that the lower unit has. What I worked out on paper gives me a speed of over 60 MPH, that isn't a misprint, but at that speed battery life would be less than half an hour. But hey, that is 30 miles and if you slow down you can quadruple that. I was going to start a thread when I got further into the project, but after reading this thread I couldn't resist tipping my hat. The crazy scooter was my design and build, plus I have built a electric Cushman stake bed truck and the above electric Smart car knockoff from China I purchased five in a container, sold four, kept one.

[capn_billl]

Originally Posted by bassman1956

You get me an electric car with a range of 100 miles and under $20-22K, and I'm sold. And the first manufacturer to do that will change the market.

Right now, the cheapies cost as much or more than a luxury sedan. They'll never break the market trend like that.

And the sad part of it is, they expect us to pay $20,000 extra to save $1000 in gas. Right now the math just isn't there, and it's not because building an electric car is more expensive than a gas car.

An electric motor plus a controller is less than $1000 retail, they battery packs are the most expensive part, but they are also being sold at a premium.

NIMH batteries are proven technology, and very cheap compared to lithium, but Cobalsys is still sitting on the patent and refusing to sell to road vehicles.

An electric car could be built and sold cheaper than it's gas equivalent with current technology. Right now it's all about "people will pay extra to save the planet".

[capn_billl]

Originally Posted by noelex 77

Unfortunately the idea you have is not going to work in the form you have stated it here.
Do the sums for energy in and out. This will show you what you can achieve with solar. If you forget about the hot water, cooking, blender and Air Con. Limited electric propulsion should be feasible.

TO make this work solar panels need to be in the 90% efficiency range. Solar energy hitting the earth is about 1000watts per square meter, (on a good day).

Modern panels are at about 18% efficiency, (affordable panels are half that 9%).

I once worked out that using peak efficiency panels and covering the entire surface of a 30' catamaran with solar panels, you could get a couple of hours of motoring for 10 hours of charging, or 10 hours of runtime at reduced speed...doable, but having some Diesel backup would be preferred.

If all you used the electric motor for is getting in and out of slip, then 4 of the big panels, (200watts), should be able to recharge you enough to get back in after a day of sailing in sunlight, (8KWH = 1 hour at 4 KW plus 2-3KWh house load). Assuming you plug in at the dock at night. That is storing in 8 * 200Amp hour batteries for a 12volt system.

It is doable,...barely. Some people have done it, there is 2 companies selling entirely solar powered boats, one a small bay boat with a pop top solar panel roof, the other a mid sized cruising cat completely covered with panels. neither is very cheap; solar panels, particularly the new high efficiency ones are still kinda expensive.

[deckofficer]

daddle,

I was going to reply to your PM, but somehow I must of deleted it. Hope your new diesel install goes off without a hitch, and I'll just admit here on the thread that I am biased and have an agenda for electric propulsion, but nothing of a commercial interest.

I'm sorry for my limp wristed attack, it was uncalled for. I do stand behind my comment that Dick Pluta knows of what he speaks.