Geld
New member
Can anyone recommend an electric outboard which would be powerful enough to use as an emergency back up for a 19 foot cruising boat in case of a break down by the main outboard engine?
Electric outboard
- Thread starter Geld
- Start date
Sticky Fingers
Well-known member
Torqeedo 1003.
Homer J
Active member
+1 their great and torqey
Seastoke
Well-known member
How long is running time as he wants it for back up.
RupertW
Well-known member
Well I’ve a 1003 and they are about 2 knot equivalents which is perfect for the 3m rib in an anchorage but I wouldn’t use it for a 19 foot boat in a current or chop. Range about an hour for me with my 550 battery but new ones come with 950.
nestawayboats
Active member
You put 2 knot equivalents but I'm guessing you probably meant 2 horsepower equivalents. The Torqeedos will definitely push most boats to more than 2 knots, even a 19 footer.
On a typical inflatable dinghy you'll get about 5.5 knots flat out, or 4.5 knots at half power. On a larger boat up to 20ft or so about 10% less. It depends on weight and drag, but with an electric motor there's not as much effect as you might expect, because there's a lot of torque available.
The market dominant Torqeedo 1003 (and now 1103) and Epropulsion Spirit are both 1kW motors, which is about 1.5hp. BUT with much more torque than a 1.5hp petrol motor, because torque is what electric motors are good at. That's why they turn relatively large propellers relatively slowly. As long as you don't want to plane, they have about the same propulsive effect (at displacement speeds) as a 3 to 4 hp petrol motor.
The run time depends on which battery you have; Torqeedos are offered with 532Wh (Watt hour) batteries that will last half an hour flat out or an hour at half power, or 915Wh batteries that will run about 70% longer than that. Epropulsions come with a 1018Wh battery, so about 10% longer run time than the largest Torqeedo option.
Ian Thomson
Nestaway Boats Ltd
Sailorsam101
Member
I think they are great things but personally i would not being using an electric outboard as a backup.
You are very limited as to the range. You can always carry more petrol. I think one day soon this will change but for now the technology of battery life to size just is not there yet.
You are very limited as to the range. You can always carry more petrol. I think one day soon this will change but for now the technology of battery life to size just is not there yet.
longjohnsilver
Well-known member
Is it not possible to jury rig the electric outboard to the boats own battery bank in case of an emergency? I know if I was relying on an electric outboard as an auxiliary I’d be setting something up to allow me to do just that.
BruceK
Well-known member
ditto and if I had to rule out a small petrol OB and I'd be looking at a bass boat trolling motor not a Torqeedo which is a wonderful bit of kit but imo not suitable for this type of task.
https://www.trollingmotors.net/blogs/selection/86933703-trolling-motor-thrust-guide
nestawayboats
Active member
The Torqeedo 1103 is rated at 70-lb thrust - with a note that they use international ISO measuring standard and to be comparable with the method generally used to measure trolling motors you actually need to add about 50% to that, ie 105-lb. I don't know enough about the measurement methods to comment further but if we go with the 70-lb thrust figure as a minimum for the Torqeedo, and use the bass boat thrust guide to which you refer, then apparently 70-lb is sufficient to be "performance thrust" for a boat weighing up to 2000-lbs (a bit less than a tonne). "Performance Thrust" being what they recommend for use in strong waves/winds...
However I'd also point out that trolling motors are designed as secondary motors, so that you can go slow to catch fish when you've got to where the fish (hopefully) are, using a larger motor. Mainly so you don't clog up your two-stroke by running it at idle speeds for hours on end.
In contrast the Torqeedo and Epropulsion motors are designed as propulsion motors, so the power delivery is different. They will push surprisingly heavy boats up to near displacement speeds, eg two-tonne 26ft yacht to 4.5 knots (we know, that's a trial we've done).
The limiting factor with the Torqeedo/Epropulsion type - but also the thing that's made them so popular as dinghy outboards - is the capacity of the integral lithium battery on top. This means you don't have to hulk around great big car batteries in and out of the dinghy. And as a back-up on a larger boat, it has the advantage of being a completely self-contained system, separate from everything else on the boat. (Your main engine may not be working because your on-board electrics have failed.) And the 1kWh lithium battery capacity is roughly equivalent to 200Ah of 12V lead acids (because you can use all the capacity of a lithium battery, and no more than 50% of a lead acid).
So a trolling motor connected to the boat's batteries would only have more range if you have 200Ah or more of batteries installed, and they are fully charged/functional when your main engine has failed.
Ian, Nestaway Boats
BruceK
Well-known member
Your argument cuts both ways. I'd sooner expect my boat batteries to be full that rely on a tender motor that may or may not have been used as well. But if you say it's up to the job and has the longevity of battery to cope with peak output pushing a heavy boat for long at displacement speed then kudos.
Bouba
Well-known member
I’ve been reading this with interest. Until now my gut feeling was that a Torqeedo was not up to the job (unless you have £40,000 for a 40hp). But if Ian Thomson says it’s good then I would take that as gospel
nestawayboats
Active member
Sticking with the Torqeedo 1103 because that's what I was quoting figures for (but the Epropulsion is quite similar in terms of propulsive effect) they're rated at least as powerful as most trolling motors and the power delivery is quite different, ie designed to achieve higher speeds than trolling motors. Torqeedo actually say the 1103 is suitable for boats up to 3 tonnes but I think that would be getting marginal. Of course there are many factors besides displacement that affect how effective it will be - hull shape, wave and wind conditions - but those factors will also affect the effectiveness of the trolling motor.
"Rely on a tender motor". Whilst you're right, the majority of the market for Torqeedo and Epropulsion 1kW motors is for tenders to larger yachts, that is not all they're designed for. Indeed people keep asking us for "smaller ones" for their tenders. But if your backup motor is also your tender motor then at least you know it works, unlike a small back up auxiliary petrol motor that lives forever on a transom bracket. (Just about the worst thing you can do to a small petrol motor is use it very infrequently.)
Ian
Nestaway Boats
"Rely on a tender motor". Whilst you're right, the majority of the market for Torqeedo and Epropulsion 1kW motors is for tenders to larger yachts, that is not all they're designed for. Indeed people keep asking us for "smaller ones" for their tenders. But if your backup motor is also your tender motor then at least you know it works, unlike a small back up auxiliary petrol motor that lives forever on a transom bracket. (Just about the worst thing you can do to a small petrol motor is use it very infrequently.)
Ian
Nestaway Boats
BruceK
Well-known member
But again the argument cuts both ways because storing a lithium battery at more than 40% charge for a lengthy period is equally bad. And your T. batteries dont come cheap. How much do you sell them for?
nestawayboats
Active member
40% for storage charge is a bit lower than the two manufacturers say, haven't got the right info here but I think Epropulsion say 70% is OK. And more significantly (as you say) it's only really long term storage that matters, like putting it away for the winter. A few weeks is fine. I generally leave the one I use for my own yacht tender fully charged during the season.
Leave a petrol outboard with petrol in the carb for more than a couple of weeks and there's a good chance it'll gum up. A lot of people now don't know how to take a carb off, let alone clean it. (British Seagull outboard owners had to know this!) Those same people are probably more comfortable with battery charging/storage discipline.
But I agree there are arguments both ways. Petrol still wins for anything above about 5hp, unless your budget is unlimited.
Re pricing, due to some drummed-up controversy earlier this year I'm allowed to contribute information on here, but not allowed to do anything that might be deemed "commercial" so quoting prices is probably not on. But it's not hard to find us online...
Ian
Nestaway Boats Ltd
Leave a petrol outboard with petrol in the carb for more than a couple of weeks and there's a good chance it'll gum up. A lot of people now don't know how to take a carb off, let alone clean it. (British Seagull outboard owners had to know this!) Those same people are probably more comfortable with battery charging/storage discipline.
But I agree there are arguments both ways. Petrol still wins for anything above about 5hp, unless your budget is unlimited.
Re pricing, due to some drummed-up controversy earlier this year I'm allowed to contribute information on here, but not allowed to do anything that might be deemed "commercial" so quoting prices is probably not on. But it's not hard to find us online...
Ian
Nestaway Boats Ltd
