Electric motors

[klevalt]

Hey All,
I have been studying the prospect of buying a boat to live on, and travel at my leisure, and I think I have decided on a multi hull due in part to the dispersment of the living space and the rising cost of fuel. I wonder how feasible my idea is (for further fuel savings).
Would a change out of the fossil fuel engine to an electric motor be a difficult undertaking? I know I can get solar panels and use wind energy, but how much space would I need for batteries? Being a novice, I guess the most basic of information would be best, however having single-handedly taken apart and rebuilt a 1968 Chev Suburban without any prior experience, I am not afraid to try new things on my own.... I would love to hear if any of you have tried this, and what was your experience. Is it worth it, with the rising cost offuel and all? any other details you can think of that would be helpful would be great!
Thanks in advance!
Karole

[Tellie]

Originally Posted by klevalt

Hey All,
I have been studying the prospect of buying a boat to live on, and travel at my leisure, and I think I have decided on a multi hull due in part to the dispersment of the living space and the rising cost of fuel. I wonder how feasible my idea is (for further fuel savings).
Would a change out of the fossil fuel engine to an electric motor be a difficult undertaking? I know I can get solar panels and use wind energy, but how much space would I need for batteries? Being a novice, I guess the most basic of information would be best, however having single-handedly taken apart and rebuilt a 1968 Chev Suburban without any prior experience, I am not afraid to try new things on my own.... I would love to hear if any of you have tried this, and what was your experience. Is it worth it, with the rising cost offuel and all? any other details you can think of that would be helpful would be great!
Thanks in advance!
Karole

Anything can be done on a boat with brains and money. But if you buy a Multi with existing diesels I think the cost conversion to electric is way out of line on any fuel savings realized. Solar panels and wind generators cannot keep up with the demands of electric drives so you'd have to add a fuel driven generator as well. I'm not sold on electric drives in the first place and believe that more likely than not in another ten years you'll be seeing alot of Lagoon owners doing the opposite of what you propose and ripping out electric drives and reverting back to the tried and true deisel. I say save the 50K+ refit and use it to buy fuel and cruise. But I know others will disagree.

[w42]

What Tellie said is valid as far as in electric drives may not be ready for prime time. Only time will tell on that one.

But, if you are willing to take the plunge, you must consider your existing power demands. It is not a matter of just dropping an electric drive in. Solar and wind will not be enough. You will need a generator of some sort. Any old generator will not do. Depending on the system, it will likely need to be a DC generator of something higher than 12v. Then you will need more batteries (again depending on the system you install). Need to find a place for those. You might need as many as twelve. Then, you may need to replace any inverters, chargers and add step down transformers to power your existing house electrics.

Summary. Converting an existing boat while keeping existing electrics is too difficult and expensive.

[henryv]

You should sign up on the Yahoo Groups electric boat forum. You will find many do it yourself types there. The discussion archives will answer many of your questions. Don't be put off by the nay sayers - there are many positive things happening with electric drives although at the moment up front costs and limited battery options are still making the systems hard to justify in pure economic terms.

[clausont]

The boat in the slip next to mine is an electric boat. The owner is very happy with it so far. He did the installation himself and it turned out quite well. His boat is completely silent - if I am not watching, his boat will just appear in the slip when he returns from an outing with no noise. He says that he has about a four hour range at about 5 knots if I remember correctly. I had thought about this, but I don't feel that an electric conversion would suit my comfort zone well enough. I want the range that my diesel provides, all things considered.

[Sunspot Baby]

I think both Lagoon and Leopard are selling diesel electric hybrids and there was a post today by a company introducing a new one sometime in 2009.

Converting an existing boat may be more cost and trouble than it is worth.

George

[mikereed100]

I found the Yahoo group to be an excellent resource. Go back and read the archived posts. In the end I came to the conclusion that electric is viable for small (say 30' and under) and lightweight boats, but not for a larger cruising boat. There are many motors made my Mars, Eteck, Perm etc that can power small boats and many companies have put together kits that include the controller, potentiometer, harness, monitors etc. For larger boats the DIY route just doesn't seem feasible at this time. If you are looking for something to get you in and out of the slip an electric would be ideal. If you need something for extended motoring or powering into headwinds and seas then an ICE remains the way to go.

Mike

[Roy M]

I just took an electric boat out yesterday to test drive it after replacing all its batteries. It's a 21 foot Duffy, using 16 six volt batteries in two banks of 24 volts to power a 48 volt motor. It was VERY cool to motor along in almost complete silence. The wake made more noise than the motor.

But, everything the others have just said is spot on, in spades for a multihull. If you are only going to use it as a powerboat, don't waste your time getting a multihull sailboat, or a multihull for that matter, since weight is the problem. Think of multis as aircraft, not lead-ballasted freighters.

Now, if lithium batteries, or some entirely new technology emerges that offers large amounts of available energy (a lightweight thermonuclear reactor using seawater as fuel?), then we're talking. Until then, if you are still set on a multi, perhaps a small diesel with adequate tanks to give you a few days of motoring capacity isn't such a bad idea. You can still fuel it with something green that smells like french fries. Then keep the boat light and sail it as it was designed to be sailed.

[DeepFrz]

kvelalt; If you look down at the bottom of this page you will find a bunch of links to discussions Ad Nauseam on electric drive motors.

[44'cruisingcat]

A friend is building an Oram 44 powered by electric motors from here: RE-E-POWER Electric Propulsion for Marine Applications

He will have a similar or slightly larger battery bank to a normal house battery set-up, (200amp hours at 48 volts I think - the drives require 48 volts) and a compact, fully automatic genset.

The drives can be retracted to improve sailing performance, or can be left down to recharge batteries when sailing.

It's bee interesting to see how well it works. I think it will work pretty well, the guy building it does his research.

[Nordic cat]

So in actual fact he will be diesel-electric for anything more than around an hour of motoring on the batteries, if that.

I have also looked at the concept, but have decided to go with full redundancy with 2 diesels. As long as they get air, water and diesel, you can normally keep them running.

This diesel electric concept is the only viable one for a cruising multihull IMO. Lugging around tons of batteries that all need to be exchanged after 5 years, as well as expensive and sensitive electronics that you will at some stage depend on to keep you off a lee shore, is not for me.

I do like the possibility of pulling the props out of the water.

Regards

Alan

[GreatKetch]

Originally Posted by klevalt

Hey All,
II know I can get solar panels and use wind energy, but how much space would I need for batteries?

The simple answer is you can NOT generate enough power with solar and wind to continuously motor a boat without wildly optimistic assumptions. Electric boats have their place, but more as picnic launches or day sailors than as long distance cruising boats.

Sails (remember those?) are way, way, WAY more efficient than turbines and batteries at extracting power from the wind. A SAIL boat is basically a solar powered boat, because the sun makes the wind blow. If you really want to be green, buy the most efficient SAILboat you can find. One you can SAIL in 3 knots of wind. One you can SAIL away from a lee shore in 50 knots. If the boat design you are looking at can't do that, then you would be better off looking at a different boat than at only partially developed technologies.

Remember, people have in the past, and continue today, to sail around the world without engines of any kind.

[44'cruisingcat]

Originally Posted by Nordic cat

So in actual fact he will be diesel-electric for anything more than around an hour of motoring on the batteries, if that.

I have also looked at the concept, but have decided to go with full redundancy with 2 diesels. As long as they get air, water and diesel, you can normally keep them running.

This diesel electric concept is the only viable one for a cruising multihull IMO. Lugging around tons of batteries that all need to be exchanged after 5 years, as well as expensive and sensitive electronics that you will at some stage depend on to keep you off a lee shore, is not for me.

I do like the possibility of pulling the props out of the water.

Regards

Alan

That's right, if he has to motor far the genset will be running continuously. No problem there though, it's just like running any motor. (except that it will start and stop itself automatically depending on battery voltage)

But for a normal motor out of the marina, the genset might not need to run at all, and once sailing the motors can recharge the batteries, then be retracted.

There are some real advantages - there is instantaneous power when you need it, no need to start engines. The engine controls can be mounted pretty much anywhere, or be portable - he's thinking about mounting them on a belt so he can walk around the boat with them - would make mooring up single handed easier.

Also he will have pretty much unlimited electricity , but without the extra weight of a genset on top of engines - he's going to use electric kitchen appliances and cooktop I think.

I'm interested to see how it works.

[Eleven]

First. The cruising Cat oftem motors for a couple of days due to calm or storm conditions or adverse winds. An battery powered boat can't do this if weight is to be kept reasonable.
Second. Modern generators and submersible motor pods are as / more efficient than the traditional 'Z' drive installation and can be retracted easily for optimum sailing performance and to clear or clean fouled props.
Diesel-electric will become the standard installation in the next few years.
What a joy to be able to slip quietly in / out of the marina without disturbing the peace. Start the genny/drive once out in open water and established under sail. Course set, that's the work done, put the kettle/breakfast on, shut down the genny when the batteries are topped up.
Single engine, twin props, rotatable drive pods, huge domestic power for electric cooking, freezing, lighting and a/c. So many options become available.
No gas, no petrol, no unnecessary fire risk and almost extra weight. For a secound hand cat I'd probably keep the 'Z'drive and add a genny to the Yanmar. A decent electric outboard should be enough for most marina entry / exits if the winds not too bad.

[klevalt]

Thank you for all of the information you have provided! I guess I am lacking a key bit if information here... the multi-hull will be a sail boat... how does this change the scenario?