Electric motor/generator ?

[Brian Schwerdt]

and for completness there are 37kWh/gal in diesel fuel so my 40 gal tank is 1.5 MegaWh of energy, show me the battery bank that can compare and not sink the boat due to its weight.

In general I agree with you, but i would point out that the conversion from diesel to mechanical propulsion is far less efficient than from battery to an electric motor. So the comparison would be more like 500kWh of batteries. But yeah, that is huge. The top of the line $100,000 Tesla Model S only has 85kWh. Most people estimate batteries are at about $250/kWh, making this battery $125,000!!!

There is a place for an electric motor on a sailboat, though. I am very happy with my Torqeedo outboard, and its battery is only 0.52kWh. I use it to push a 22' boat in and out of the marina on a smallish inland lake. For a bigger boat or even open water, the tech just isn't there yet. That could change in a decade or so as the growing electronic c car market creates demand for better and cheaper batteries.

 

[mitiempo]

.....the tech just isn't there yet. That could change in a decade or so as the growing electronic c car market creates demand for better and cheaper batteries.

The batteries are close - Lithium (LiFePO4). But you still have to return the AH used by charging. Unless you plug in each night - as a car does - it doesn't work. Range would still be an issue as well of course.

 

[capta]

There is a place for an electric motor on a sailboat, though. I am very happy with my Torqeedo outboard, and its battery is only 0.52kWh. I use it to push a 22' boat in and out of the marina on a smallish inland lake. .

Over the last 5 years of cruising, from the states through the Caribbean, I have seen exactly one of those electric outboards, and probably several thousand gas ones. It doesn't seem that they are taking over the market, just yet.

 

[Brian Schwerdt]

Over the last 5 years of cruising, from the states through the Caribbean, I have seen exactly one of those electric outboards, and probably several thousand gas ones. It doesn't seem that they are taking over the market, just yet.

No, you have to really want to go electric. They are expensive and short range. Cruising in Caribbean with one would be a bad idea. Heck, cruising the great lakes would probably be a bad application. Oneida Lake is only 22 miles long and 5 miles wide. That is about the largest lake I would recommend for it.

I have also seen two low-speed electric power boats cruising the Erie Canal (think pontoon boat).

As for cars, a commuter is a great use of an electric car. The market is growing fast, too; sales are nearly doubling every year. This is creating demand for batteries much better than LiFePo such as Lithium air or other breakthroughs we haven't thought of yet. 10 years from now I wouldn't be surprised if they are good enough for Great Lakes cruising. But I still wouldn't recommend them for offshore!

Bottom line, in 2014 you should go with liquid fuels (gasoline or diesel) unless you are on a small lake.

 

[BobM]

Just remember my friends experience with a rental in the BVI. They said the engines depleted the batteries rapidly am
Nod that the large genset was loud and annoying at anchor and had to be run for hours. They won't be renting another.

 

[Bob 04 H260]

I think there may be applications for electric

Sailboats used as daysailors where the auxiliary engine is only used to get them in and out of a marina and they are in a slip each night that has power available could make sense.

Here is a utube link to the Hunter hybrid 36 ft sailboat,

http://youtu.be/qy99hXGxkBA

I don't know anyone that has one. I saw one at Dinner Key a couple of years back. It was in and out from time to time, I never had a chance to talk to the owner.

While on a mooring ball in Marathon (Keys) they used an electric powered boat to pump out the 225 boats in the field. He carried a Honda generator as a backup if his batteries got low. It seemed like a great solution, not idling an engine all day while doing pump outs and maneuvering between boats, no engine fumes, no noise.
Bob

 

[shemandr]

I think this discussion started with an observation that that cruise lines have converted to diesel generators running electric propulsion systems. It has drifted into all electric auxiliaries (Not a bad thing). As I understand it, the object of the diesel/electric wasn't to eliminate fumes or noise. It was to take advantage of the diesel's optimum power/fuel efficiency to run the electric propulsion.
I think it was Nigel Cador who wrote a series of articles for Sail on this subject. He was part of a European study on how to more efficiently use diesel fuel, and reduce emissions. There was some great gee whiz technology presented including a DC electric "Motor" which could generate electricity while sailing via the prop spinning. As I remember the start up costs wiped out any gain in efficiency for a sailboat auxiliary. But better systems don't happen by themselves. Someone has to look for a better way. For cruise ships, which generate a cities worth of electricity 24/7, the systems are proven. For normal sailboats it's a tough sell. Joystick docking would be nice.

 

[Chris Patterson]

A little battery side note:
My buddy had a Prius that the battery went south. The replacement cost was prohibitive. And sold the auto for 600 bucks, it was all he could get for it. Pretty little car too. But dead in the water..

 

[Gunni]

My genset is 8kw. My ME has an 110 amp alternator, a far cry from 60kw. I sure do not see where in the world you can get 60 kw without 60 kw of gensets, enough solar panels to cover half a football field, and or one gigantic windgen for a massive battery bank which would weigh more than the genset and ME. A solar array that takes up 128 square feet, can produce about 1400 watts, or 1.4 kw. You must have a GIGANTIC cabin top if you really get 5kw from them. I do believe, if you check again, you have more like 500 watts of solar on your cabin top, not 5kw, or 5000 watts I must be missing something here, or I'm just no good at math. Just so you and I are talking about the same thing; 60,000 watts, not 6,000 watts, right?

I am referring to kWh output of a Diesel engine at the shaft, not the attached electrical generator. The output of your AC generator and your auxiliary alternator was a design decision unique to your application, not an optimization for DC locomotive power. The Gunboat Moon-Wave system does everything with 44 kWh of diesel power - about the same as my conventional 54hp yanmar, and 10hp Kubota diesels. Best of all, moving the boat under power does not require the diesel racket.

 

[Gunni]

A catamaran is a lot a fiberglass and beam to take care of, on the other hand that 28ft of beam makes for lots of PV mounting space! If I had 35kW of PV supply I could run my A/C system off of the inverted battery pack. Better yet, convert the compressor to one of those 3phase DC compressors and skip the inverter loss and complication.

 

[capta]

I am referring to kWh output of a Diesel engine at the shaft, not the attached electrical generator. The output of your AC generator and your auxiliary alternator was a design decision unique to your application, not an optimization for DC locomotive power. The Gunboat Moon-Wave system does everything with 44 kWh of diesel power - about the same as my conventional 54hp yanmar, and 10hp Kubota diesels. Best of all, moving the boat under power does not require the diesel racket.

Funny, I get the same experience from sailing my boat; no diesel noise!
Last year we traveled about 2500 miles through the West Indies and put less than 20 hours on the engine, so diesel noise wasn't really a concern. But thanks for the input.

 

[Gunni]

Yep! And if you are navigating with an Imray-Iolaire chart you are using charts created by a guy who did so with an engine-less yawl and a taffrail hydro-generator.

 

[Bill Roosa]

And capta's comment in post #31 says it all, SAILED 2500 miles and ony 20 hours of engine time. So I'm thinking that since I already have a free source of "motive power" (aka the wind) all I really need is solar and wind generation sufficient to met my demand at anchor and a tariff rail water generator for while under way. No need to refit the entire boat with regeneration with things like the Duo-gen (wind & water generator design) out there. I'd rather invest in a better set of sails and learn to use them better than all this electrical stuff.