Diesel-Electric Propulsion System

[kmbh69]

Hello,
I read about the diesel electric propulsion system. There is a generator (with diesel motor, it may be portable, too) and an electric motor, which can be mounted as in-line motor-shaft-propeller or submerged motor (it may be orientable, too), this variant can be mounted as 2 electric motors on the catamaran hulls and the generator somewhere in the center of the boat.
Could you please tell me the advantages/disadvantages (decreased output ?) ?
I would like to adapt such a propulsion system to a sailboat 7,3 m long (22 feets), thinking that a submerged motor is difficult to steal and the generator can be dragged on wheels from the mooring place to the car.

[David M]

There are economies of scale with electric propulsion systems. Your boat is 22 feet long. Electric propulsion systems are also more complex. If the system is not engineered well then more complex can also mean less reliable. On a boat of your size, the thrust to weight ratio or your propulsion plant will be much lower than if you had an outboard and a can of gasoline.

I am not going to make a judgement call on whether or not to do this, I just wanted you to be aware of these factors.

A five horsepower outboard is relatively easy to remove from its mount and to store under the cockpit setees, locked away out of sight.

If you much prefer electric then have you looked at the Torqueedo? I think this would be a nice application for a 22 foot boat.
http://www.torqeedo.com/us/hn/home.html

[JRM]

Originally Posted by kmbh69

Hello,
I read about the diesel electric propulsion system. There is a generator (with diesel motor, it may be portable, too) and an electric motor, which can be mounted as in-line motor-shaft-propeller or submerged motor (it may be orientable, too), this variant can be mounted as 2 electric motors on the catamaran hulls and the generator somewhere in the center of the boat.
Could you please tell me the advantages/disadvantages (decreased output ?) ?
I would like to adapt such a propulsion system to a sailboat 7,3 m long (22 feets), thinking that a submerged motor is difficult to steal and the generator can be dragged on wheels from the mooring place to the car.

electricboats : Electric Boats

There are a few of us electric boaters here, but you'd get much better information over at the yahoo group. There are tons of people over there that have already solved your exact problem.

David is right. An electric outboard is by far the best way to go. Skip the generator, you won't need it. Go with the Torqeedo if you like fast and expensive, a MinKota Riptide trolling motor if you don't mind a bit slower but cheaper.

Take a look at the Schock Harbor 20s. They come standard with an electric solution. There's a ton of them down in the harbor here. I have converted my 30' keelboat to electric along the lines of what you are asking, and I would advise against it in a boat any smaller than about 27 feet (for an inboard solution).

I have a MinKota on my dingy for use as a tender. It's perfect for what I use it for, and several of the J24s down in my harbor use them as auxiliaries. You can buy one at WestMarine for $250, toss on a cheap battery (or even an expensive one), slap on a fuse and be on your way.

JRM

-- I'm no expert, but I do have both an electric auxiliary sailboat and an electric dink, which I'd be happy to answer any questions about. However, the real experts are over at the yahoo group.

[GordMay]

Greetings and welcome aboard the CF, kmbh69.

[klem]

What you are talking about is a series hybrid system. This system makes sense for people who have an electric propulsion system with batteries and occasionally need longer range than their batteries will provide. It allows you to use the electric system almost all of the time, then use the generator at the odd time when the batteries are running low. For normal use, this system rarely makes sense. The main reason is that it is significantly more complex and less efficient. Complexity has to do with the shear number of parts and connections involved. The reason that it is lower efficiency is the number of energy conversions involved, you convert chemical energy to rotary motion to electrical energy back to rotary motion. Each time you convert energy, you loose efficiency.

As others have said, if you want to have electric propulsion, look into something like the torquedo, it will be simpler and cheaper.

[kmbh69]

Thank you for your answers. I am in Friesland (Germany, North Sea Coast) and here there are some companies which offer complete solutions, I'm afraid to give names because I do not intend to advertise companies here, but with a search on Google they can be found.
Some of the models I saw were easy to install, only a small drill for fixing the motor and the 2 plates. I don't have to adapt anything, is industrial made. They simply ask the displacement and dimensions of the boat and then propose a certain model of electrical motor (or a torquedo motor, but is not very known here), then you have the motor power requirements in watts and you add the power consumption you will extra need and they propose the generator model, too.
The idea was to have anyway a generator for other purposes, too. The boat has also a chemical toilet which could be replaced with an electrical one and I was thinking about the idea of mounting a small sink and a fresh-water tap inside, which requires an electrical pump, too (maybe a water heater, too). There are maybe other consumers of electricity on the boat, I could give up the gas cooker and install an electric cooker instead or I could try to heat the cabin of the boat electrically with hot air (somehow similar to a greater hair-dryer). That is why a normal car battery would not be enough (maybe is enough for the navigation lights or some DSC radio or AIS-system).

[bill good]

G'day kmbh69

On a 22' boat you do need to find out about the Torqeedo electric motor. It is a product developed in Germany!! The use of a 1000watt inverter type generator on such a small boat would extend the motor range if needed. You will most likely only need the motor for getting out where you will have sail power. Battery now is at the stage where you would be looking at LIFEPO4 but allow for a degrade factor of .7 & it will last you over 10yrs based on after 7 yrs you have 70% of the 1st year capacity & the drop off is slower from the 7yr point.

Weight is a critical on such a small boat.

[Adelie]

Originally Posted by kmbh69

Hello,
I read about the diesel electric propulsion system. There is a generator (with diesel motor, it may be portable, too) and an electric motor, which can be mounted as in-line motor-shaft-propeller or submerged motor (it may be orientable, too), this variant can be mounted as 2 electric motors on the catamaran hulls and the generator somewhere in the center of the boat.
Could you please tell me the advantages/disadvantages (decreased output ?) ?
I would like to adapt such a propulsion system to a sailboat 7,3 m long (22 feets), thinking that a submerged motor is difficult to steal and the generator can be dragged on wheels from the mooring place to the car.

Diesel electric works on medium-large ferries despite it's large power loss of 20-30% because it can respond very quickly changing thrust levels or even reversing thrust and because this is neccessary for quick turnaround times at ferry landings. On very large motor vessels, reverse is obtained by stopping the motor and restarting it spinning backwards, there is no reverse gear, docking usually involves tugs. At cruising speeds mechanical drives have a 3-10% power loss.

Also ferry runs are typically shorter than normal frieght or passenger vessels so the ferry's engines aren't operating at optimum RPM's for very long so the efficiency advantage of mechanical drive does not have as long to kick in, the better turn around times make up for some or most of the efficiency disadvantage.

For a cruiser the efficiency of a mechanical drive is the way to go.

For somebody just day sailing the way to go would be a larger house battery, and a trolling motor to get in and out of the marina or mooring. If you are in a marina you would have a charger running off of shore power to recharge the battery. On a mooring you would need a solar panel or 2 to charge the battery between outings.

For trips longer than a daysail I would get an outboard and an extra solar panel. On a 22' boat you might be able to make 3kt or a bit over if you had sun and enough panels to drive the trolling motor flat out.

Personally I intend to add a small trolling motor on a outboard bracket to the next boat (hopefully a 36'/11m boat) so I can ghost in and out of marinas on battery power.

Optimally someone would design an electric motor that piggy backs onto the prop shaft between the transmission and the packing gland. That way the boat can be ghosted on battery or solar power, or it can generate power when the wind is up and the boat is moving along well under sails.

[David_Old_Jersey]

Originally Posted by Adelie

Optimally someone would design an electric motor that piggy backs onto the prop shaft between the transmission and the packing gland. That way the boat can be ghosted on battery or solar power, or it can generate power when the wind is up and the boat is moving along well under sails.

like this?.......






Hybrid system based on the Beta Marine range of engines from 10hp to 90hp.



The above is one of the more idiot freindly explanations of the installation that I have seen . Far more on:-

Beta Marine | Marine Diesel Propulsion Engines and Generating Sets

Seagoing Hybrids - Hybrid Electric Marine Propulsion

Why fit a Hybrid? - Hybrid Electric Marine Propulsion


Anyone have views on the reasonablness of these claims?:-

How fast can I go using the electric motor ?

The standard system uses a 10kW motor (13hp). A Malo 46' yacht has a hull speed of approximately 9kts and requires 100hp to achieve this. However at 6kts it only needs 8kW so for this vessel the electric drive can achieve just over 2/3 of hull speed in calm conditions.

How far can I go on my batteries?

This depends on the size of your boat, the size of your battery bank and how fast you want to go. One example would be to take a 40' auxiliary vessel that requires around 4kW to achieve 5-6 kts. With four 200Ah batteries we would have around 7.7kWh of usable energy storage. We could thus travel for around 2 hours at 5-6 kts. Increase the size of the battery bank and you can go faster or further.

Enhanced Power

(written aimed at the canal boat market - but I think much also applicable to yachts - DOJ).

Your hybrid is a portable power station. With the powerful generator capability, a substantial battery bank and inverter technology, you have an optimum power solution. Some of our boats take full advantage of this by being all electric (no gas onboard). Every domestic appliance you use at home can now be powered on your boat : Washer/dryers, electric oven & hobs, toaster, kettle, fridge/freezer etc.

Set the boat up with a normal domestic ring main and there is no need for under powered and costly 12V appliances. For those few items of equipment that need 12V you have a step down converter capability from the main battery bank.

Forget running your generator at dusk/dawn to top up the batteries. The enhanced battery bank of the hybrid supplies, in complete silence, more than enough power for the night and can be charged again when you are under way the next day.



I've not asked for any prices

[Adelie]

Exactly like that. I found that product yesterday or day before.

[kmbh69]

@David_Old_Jersey
Well, thank you, it looks nice, but I'm afraid of the price. For the moment I just dream to have such a system, but more realistically maybe somewhere in the future.
I think the idea of a small outboard motor and a big battery for instruments, lights etc. is for the moment better.

[deckofficer]

I would like to create a place for everyone thinking about electric, and diesel-electric propulsion, fully electric galley, electric dinghy, diesel DC gen-sets, and 48 VDC (and higher) inverters, can communicate ideas, links, experiences, and pictures. Since I have been the victim of thread closures when such topics veer off, I have added this topic to my own forum. When your on your own turf, you know posting history will not be lost. My forum is a rather oddball mix of subjects, 80% hot rods (T-buckets) 10% for family care givers, and 10% sailing/cruising. This is where you will find the topic "Integration of systems" in the "Hybrid Drives For Sailboats" thread that is part of the "SAILBOAT CRUISER'S FORUM". All are welcome, please give links to all the breaking news on hybrid drives that you have come across here....

Integration of systems

[FarCanal]

Hiya all,
First post, try this site for electric propulsion. Very interesting.

Above the Waterline | Electrical, Electronics and Propulsion Products


Mik

[deckofficer]

Mik,

Welcome to CF and thanks for the link. I added it to my growing collection. What is your interest in EP?

[FarCanal]

Hiya Bob,
Thanks for the welcome, always been interested in alternative forms of transport/propulsion and I was pointed to this site a while ago. I know a of a few folks over here in England who have hybrid canal boats, they are very enthusiastic about them. Good to chat.

Mik