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Old 01-06-2007, 10:50   #61
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I admit I am fascinated by electric propulsion. As with everything on a boat there are pros and cons, some of them already discussed above. For me the biggest "pro" is near silent running. The sound of my engine ticking away is comforting when the wind dies but I sure love it when I can shut the damn thing off again. I can also picture myself anchored up for the night, the wind switches, the boat drags, I run to the engine controls, turn the key and ...nothing. On an electric boat with a battery bank the key is turned ...instant full torque power with no warm-up, enough juice to get off the shore and get the sails up. Of course this is just one scenario and electrical systems can fail too, but I think electric propulsion has enough advantages to warrant a good, hard look.

As 44 Cruisingcat points out, electric propulsion can be very pricey if one goes with systems like the Ossalite and Solomon. On the other hand, if the boat is light enough a much cheaper system can be put together using off the shelf motors, controllers, chargers, converters etc. Thoosa markets a relatively high-end system that is still less than half the price of the Solomon system. When I priced a system for my own cat using Perm motors and a 48V genset from Ample Power it came to about $26K including battery bank. Not that much more than a couple of Yanmars with saildrive.

Concerning repairs, the individual components are not that expensive (motor $800, controller $400) and spares could be carried. To be honest, if I were in the boonies I would feel more comfortable with a diesel, some baling wire and, my own tool of choice when performing delicate repairs, an old axe. But if I could motor silently when the time comes it might be worth the risk.

Only time will tell how reliable electric propulsion is over the long tem in cruising boats. Fortunately we have a growing database in the Lagoon 420's, Leopard 43, African Cats etc.

Mike
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Old 01-06-2007, 17:29   #62
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Quote:
Originally Posted by Steven Prince
The diesel generator is only there for when the batteries run to low. Even if you douse the generator if it does packup you've got the batteries as a backup. Most cruising boats carry a generator aswell as having diesels meaning there are 3 things to go wrong. Those that don't carry generators run the engines under only a limited load to recharge the batteries, which we all now is not very good for a diesel engine. A generator runs at the optimum speed for economy and engine life.

The power output doesn't really mater whether it is electronically controlled or not. If the engine has a CPU which I believe nearly all diesel engines do now then it will have a host of electronics to go wrong. Still need the startor though don't you, I'm sure not many can be hand cranked now.

.
You ought to look into how much current an electric motor (or 2) powerful enough to push a 55 foot boat will draw. You'll find that you WILL need to run the genset to motor for any length of time. Either that or carry a tonne or more of batteries.

Most cruising boat owners I know (in fact, on reflection ALL of them) DO NOT have an on-board generator. They rely on solar, wind, and (as a last resort) the alternator on their auxilliary motor.

It's funny that you would think having 2 engines instead of one is just one more thing to go wrong. Most people consider it a bonus - if one engine stops, you still have the other. it's called redundancy. Like having 2 rudders - it's usually considered one of the advantages of catamarans.

And the fact is that small marine diesels do not as a rule have ANY electronics associated with their operation. They have an electric starter, alternator and some basic instruments, and that's it. They will still run fine if the alternator and instruments are not working. Some of them can still be hand cranked if the access is there. A starter motor is electric, not electronic - nowhere near as delicate.

Most boats do carry an array of electronic instrumentation, it's true, but ask most cruising people what gives them the most trouble - probably 9/10 will answer either electronics or refrigeration.
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Old 02-06-2007, 11:19   #63
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Steven,

You seem to have a good understanding of diesel-electric's potential. Still, if you haven't already seen it you may want to read Nigel Caulder's 1st article of a 3 part series in the June/July issue of Professional Boatbuilder. This 1st part seems to be just an update to the "white paper" that has been available on Glacier Bay's OSSA web site for the past couple of years.
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Old 02-06-2007, 16:36   #64
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Originally Posted by cat man do
Quite the opposite I would have thought, a good cruising boat will usually get good resale, a racing boat usually doe'snt get as good a resale.


Dave
I meant my boats resale value is unimportant as i don't intend on selling it.
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Old 02-06-2007, 16:41   #65
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Originally Posted by cat man do
And how long are those batteries going to last if you spit the rig and punch a hole in the boat and swim the motor ?

Enough to get you anywhere?

At least twin diesel/twin outboard has redundancy built in.

Electronic nav ?, yeah, I carry 2 handhelds and paper on every trip, again, redundancy.

Dave.
Sail Power, with twin electric motor powered by batteries then generator. How much redundency do you have their. First of all you can always wait for wind to come so that you can carry on to your destination other wise you use the engines. My plan would be to sit back and relax. The electric engines are purely there as a backup or for close quater manouevering.

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Old 02-06-2007, 16:56   #66
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Originally Posted by 44'cruisingcat
You ought to look into how much current an electric motor (or 2) powerful enough to push a 55 foot boat will draw. You'll find that you WILL need to run the genset to motor for any length of time. Either that or carry a tonne or more of batteries.
Quote:
Originally Posted by 44'cruisingcat

Most cruising boat owners I know (in fact, on reflection ALL of them) DO NOT have an on-board generator. They rely on solar, wind, and (as a last resort) the alternator on their auxilliary motor.

It's funny that you would think having 2 engines instead of one is just one more thing to go wrong. Most people consider it a bonus - if one engine stops, you still have the other. it's called redundancy. Like having 2 rudders - it's usually considered one of the advantages of catamarans.

And the fact is that small marine diesels do not as a rule have ANY electronics associated with their operation. They have an electric starter, alternator and some basic instruments, and that's it. They will still run fine if the alternator and instruments are not working. Some of them can still be hand cranked if the access is there. A starter motor is electric, not electronic - nowhere near as delicate.

Most boats do carry an array of electronic instrumentation, it's true, but ask most cruising people what gives them the most trouble - probably 9/10 will answer either electronics or refrigeration.




I thought I'd said earlier on in this thread that the engines are purely for manoeuvering in close quarters or for in an emergency. This boat is primarily a sail boat, not a motorboat. If I was building a motor boat I would go with two nice diesel engines as you have. For me though, I want the piece and quiet of a sail and then when needed the electric motors.

I hope to only use the engines for about 30 mins a day. when pulling the anchor up and when setting it and thats only if the wind conditions are suitable for me to sail off.
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Old 02-06-2007, 18:15   #67
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Quote:
Originally Posted by Steven Prince



I thought I'd said earlier on in this thread that the engines are purely for manoeuvering in close quarters or for in an emergency. This boat is primarily a sail boat, not a motorboat. If I was building a motor boat I would go with two nice diesel engines as you have. For me though, I want the piece and quiet of a sail and then when needed the electric motors.

I hope to only use the engines for about 30 mins a day. when pulling the anchor up and when setting it and thats only if the wind conditions are suitable for me to sail off.
We all hope to use our engines for only 30 minutes a day. (Or less) It doesn't always work out that way though. But even to run for 30 minutes, a 10kW motor will pull 416.6 Amp/hours. (Assuming 100% efficiency) So you will need AT LEAST 900 A/h battery capacity if you want to avoid running the genset. (Or buying new batteries frequently) Not light. Then, even if you had a large solar array, say 500 W, it would take 10 hours at 100% to replace the power used in that 30 minutes. Not including uses such as refrigeration, or lighting, etc etc. So virtually any time you motor, you will almost certainly need to run the gen.

If you seriously want to maximise the boats ability to sail in very light conditions, then outboard power is arguably the easiest way to do it. Very light, fully retractable, and cheap.
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Old 02-06-2007, 18:24   #68
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Quote:
Originally Posted by Steven Prince
Sail Power, with twin electric motor powered by batteries then generator. How much redundency do you have their. First of all you can always wait for wind to come so that you can carry on to your destination other wise you use the engines. My plan would be to sit back and relax. The electric engines are purely there as a backup or for close quater manouevering.

Steve
As I said, great if coastal hopping near areas who do repairs and have a CG, but get anywhere remote and you won't get a tow, or get a repair done.

I doing a passage and you spit your a frame rig, do you think the electric motor's will have a 700nm range to get you to a repair facility.?

If in amongst reefy tidal stream areas will the electric motors last the distance in no wind? or will you end up on the rock's?

Dave
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Old 02-06-2007, 18:42   #69
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Steven, if you are determined to use electric propulsion, you might be interested in this website for fully steerable and retractable drives suitable for electrics. : SPW - Boat Propeller and Shaft Makers

Also here: RE-E-POWER
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Old 04-06-2007, 00:39   #70
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Originally Posted by 44'cruisingcat
If you seriously want to maximise the boats ability to sail in very light conditions, then outboard power is arguably the easiest way to do it. Very light, fully retractable, and cheap.
This is something i'm seriously considering at the moment. I do like the idea of going electric tho, so I might design the hull around it and have it installed at a later date when there's been a few more developments.
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Old 06-06-2007, 08:27   #71
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What are peoples thought on diesel outboards. Also if outboards are fitted are you best buying a small genset or do people use the outboards for charging their batteries.

I'm looking at having a well in the hull that the outboard can go down into and can later be used for an electric drive system as soon as the technology has moved on. Not sure which direction to take at mo. Still prefer the idea of an electric drive.
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Old 06-06-2007, 19:54   #72
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I've looked at diesel outboards too. ATM the only ones available here (Aus) in the kind of size I need are Yanmars. They are much heavier than petrol, and much more expensive. (About twice the price) From memory the Yanmar ones did have a decent size alternator, but I intend to use mostly solar power anyway. (And possibly wind) The benefits would be the better fuel economy, and the comparitive safety of diesel fuel. Maybe reliability too. I can to some extent compensate for the increased volatility of petrol by setting up the entire fuel system so any leaks will immediately drain overboard, and the difference in consumption wouldn't offset the initial price difference in any reasonable time frame. From what I have learned, modern four stroke outboards are pretty reliable too.

Schionnings ( Schionning Designs - ) use the outboard wells in a lot of their designs. There are sometimes issues with the lifting gear, and also the lifespan of the motors can be shortened because the environment inside the lockers they are installed in is very humid.
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Old 06-06-2007, 20:01   #73
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Steven, what material do you intend building from?
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Old 07-06-2007, 00:41   #74
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Plywood and Epoxy.
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Old 07-06-2007, 07:13   #75
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Steven, if you are determined to use electric propulsion, you might be interested in this website for fully steerable and retractable drives suitable for electrics. : SPW - Boat Propeller and Shaft Makers

Also here: RE-E-POWER
Thanks for the links, I would be interested in the RE-e-Power units for a catamaran. I will be investigating that before I will need to repower or replace the current Yanmar saildrives I have. Very Interesting
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