Small electric outboards?

wragges

wragges

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Joined
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Nottingham, UK
www.minstercomputers.com
Hi All,

I'm toying with the idea of buying an small electric outboard to use from shore to swinging mooring and back. Its on the Orwell and around a mile each way to/from the hard.

It's a 3m inflatible with 2 largish adults and up to 2 kids onboard.

Any recommendations or considerations please?

What size of 12v battery should I opt for, clearly small/light/portable, but these things appear to have around a 30A power consumption. So I guess i'm looking at 45-55AH at the 20A rate?

I have a 12v socket in the back of the car so could easily recharge it on the 3 hour drive to the boat.

thanks,
 
I bought a cheapish electric outboard from Ebay last year.

An East European manufacturer I believe.

My use is for suveying rivers etc.

The unit used quite a lot of amps from the 80amp battery in less than 2 hours, with me and surveying kit in a 2.8m inflatable.

Surveying the same river last December, it would not go against the current, so has a max speed in the region of 4.5 knots.

There are bigger units around, but imagine they use quite a lot of power.

The retailer told me that at full speed they use a lot of power, but at slower speeds are more economical

Not sure that I would want to go to sea with the limited power supply, especially with a quite heavy load that you are planning.

Good points are that they are very quiet, and very manourverable with 5 forward speeds and two reverse.

IMHO petro, engine is better for endurance.
 
The subject was on here not too long ago but i cannot find the thread now.

To my mind the weight and limited capacity of the battery makes them a non starter. You wont want to leave the battery in the dinghy so you'll have to lift it onboard so you'll want to limit the size then you'll limit the speed and the range.

If you do pursue the idea check very carefully the specs especially relating to current consumption vs speed etc. Some of the figures are quoted in such a way that they are very misleading. A mile is a fair distance and there will be times when you what to do it in the minimum possible time and even against the tide. Creeping along at one knot because that's all you can afford from the battery will be no good if the tide is running at two knots in the opposite direction!

Also be very wary about comparison figures with petrol outboards especially quoting things like thrust. Put a very fine pitch prop on one and you'll get the static thrust OK but you wont get any speed.

Fine if you want to creep about in slow moving water quietly for short distances but otherwise a no as far as I am concerned.
 
I recently seen a programme showcasing a new elec outboard called the "torpeedo" they had a few models but they looked very good engines.
 
All comes down to energy density - the battery can only hold a fraction of the energy that a gallon of petrol can hold -so per unit mass (or weight since that's what you will experience) the petrol will win hands down.

If it were a short distance - electric probably would be ok - but with the load/distance I would want a petrol with more power - to explain what I mean - the petrol could, if I wanted, be used at full chat for the whole distance there and back with the tender full - the electric could not. Don't just go in power output, but consider for how long that power could continue to be developed.
 
[ QUOTE ]
I recently seen a programme showcasing a new elec outboard called the "torpeedo" they had a few models but they looked very good engines.


[/ QUOTE ] Torqeedo

http://www.torqeedo.com/en/hn/home.html

I roundly criticised one on here a few months back because they claimed it had the "Thrust of 6hp" engine. but in reality only a power of just a bit more than 2hp. That was either in the lounge which is unsearchable or the thread was pulled. Possibly because of my scathing comments or possibly because someone with a vested interest put in a plug for it. (I think it was the Torqeedo Cruise 2.0)

There does now seem to be a range of lightweights that use rechargeable lithium manganese batteries which anyone wanting a light weight might like to look at.

I am sure that they are very good engines but it is just the limited speed and range that you must be aware of and in the case of the larger ones like the Cruise 2.0 the weight of the battery (That one is 24volt so uses two 12 volt batteries in series) Study the figures quoted carefully and be sure you understand them.
 
A friend bought one to do the same job at Fareham, but sold it again after one use, no thrust, no speed and not up to going against the tide. On a quiet Lake it would have been perfect. /forums/images/graemlins/grin.gif
 
I have a 30lb thrust version (about 1HP) and it is great, I use it on the back of a 2.4m tender and as a stern thruster for my 22ft yacht.

For the use you describe I would go for a small petrol engine, there are still 3.5HP two strokes to be had - go for one of them.
 
They're not designed for esturine use. Trolling a swin on a lake is one thing, hauling a weekends gear out a mile even downriver, is something else. I agree, go for a small outboard. 2-stroke if you can fined one, the current generation of small 4-strokes are more trouble than they're worth.
 
I had a Honda 5hp.

Heavy (For the output) a Dog to start, and a bitch when cold.

Can't lean it at any old angle, only one side, or oil runs out, and needs oil changes too... /forums/images/graemlins/confused.gif
 
Group test of 2.5hp 4 strokes and the Torqeedo in ST that came through my letterbox today. The fact that they include it with this size engine gives a clue. It rated the best if you exclude ££££ of which it cost many.
 
[ QUOTE ]
and the Torqeedo

[/ QUOTE ] The Torqeedo? Torqeedo is a brand name they make a range of electric outboards of 400watts, 800watts and 2000 watts consumption but which only deliver a propulsive power of 175 300 and 900 watts.

Remembering that 1hp = 746 watts it means that the most powerful , which is only available as a 24 volt motor incidentally, delivers approx 1.2 hp. They claim however that it is equivalent to a 5-6 hp petrol engined motor on the basis of its static thrust. Great if you just want to pull at a static object.

As I said before, check all the technical details carefully on the website I gave.
 
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