Electric Outboards

[Graham W]

Here's an interesting perspective on why some Torqeedo 1003 owners report horrendous noise problems and others don't - it's all to do with the DC motor.  I've recorded my Torqeedo at 90dB and the most intrusive part of the noise is a high-pitched whine, which apparently makes it sound 20-30% worse than the measured noise level.  The equivalent ePropulsion motor, mentioned above, claims only 60dB.

I'm told that on earlier versions of the Torqeedo (specifically those made in 2013, like mine), the DC motors were quite large, without a noticeable positive impact on power and speed but with additional noise and vibration, especially after it had been used for a bit.  When problems about overall noise levels started to come through, Torqeedo put a smaller motor into the unit.  The remedy for those of us with 2013 units is to replace the motor at a cost of just under £400!  Isn't life grand?

[Michael Rogers]

It'll be interesting to see whether these new ePropulsion OBs are 'torqeedos' in respect of voltage and use of a high(er) revving motor + reduction gearing; or whether, regardless of their look-alike appearance, they try something different.

There are presumably sound (pun genuinely unintentional in this context!) engineering reasons for the Torqeedo approach. Because otherwise the trolling motor set-up - lower revs from a submerged motor and no reduction gears - surely means less noise without really trying? It must be a matter of a torque curve or two, and the battery set-up which gives the greatest range for a given weight. (And a few dozen other considerations.)

Talking of batteries and weight, there is a 12v 100Ah LiFeP04 battery currently for sale on eBay (not Alibaba) which claims to weigh in at 7.5kg. If true, that's amazing.

[Peter Taylor]

I've always attributed the noise from my Torqeedo to the gear train rather than the motor simply because that's what tends to make the noise in model boats! Torqeedo use a brushless outrunner motor ( https://en.wikipedia.org/wiki/Outrunner ) - I first came across such things in model speedboats and apparently they are also used in model aircraft. Such motors combine high torque with high efficiency but have a rotation speed which is inherently faster than a conventional electric motor. Too fast to drive a full size boat propeller so it has to be geared down. I've always assumed that the noise problem was due to Torqeedo trying to get as long a range as they could out of the relatively small battery by making the motor as efficient as possible and then gearing it down so the propeller could also operate efficiently.

Trolling motors just leave you to attach a big battery or to always use a very slow speed. Those that have a direct drive presumably have a conventional motor which is less efficient than an outrunner.

Being brushless, the motor isn't exactly "DC" but relies on an electronically switched supply to keep it turning at the chosen speed.  Obviously the switching has to be very fast and it is a potential cause of noise and vibration from the motor. Possibly the smaller motor which Graham mentions features a different winding pattern designed to reduce vibration. The design trade offs would appear to be speed v torque v noise v efficiency. My guess is the ePropulsion OBs use similar technology to the Torqeedo because the physics forces them to.

As an aside, I've recently rescued my 14 foot Canadian canoe from long neglect and a couple of days ago I motored down to Ocean Village Marina (about 4.5nm round trip) using the Torqeedo 1003. The canoe is very light (too light for easy paddling, it gets blown by the wind) and the Torqeedo can drive it at 4kts using about 150W power.  If I'm drifting with the current it needs less than 10W to give steerage way. My trip to Ocean Village took about 2.5 hours and I used about 40% of the batteries capacity (according to the display).  Coming back we were going into quite a strong (and very cold) head wind. On the canoe, or my 15' racing dinghy, the Torqeedo works well.

Peter

[Michael Rogers]

Does anyone have any more info on ePropulsion outboards? - specifically on price, and how one might get more meaningful info, in the (strange) absence so far of a UK dealer, other than that from a rather over-glamorous website.

The lack of UK dealer interest seems odd. Plenty of intra-EU dealers, so that can't be an impediment. Anyway, you'd think business with Hong Kong would be right up some brexiteer's street. (Sorry sorry, lets NOT go up that particular street here. This forum is wonderfully politics-free, let's keep it that way. I consider myself severely reprimanded and officially cautioned.)

Michael R

[Michael Rogers]

 Further re eProp (and Torqeedo), there are two (among several) relevant clips on Youtube. In one, the price of the eProp Spirit 1.0 in Oz was given as Au$ 2690, which is about £1600: so apparently no cheaper than the Torqeedo. The other is a voiceover-less dry (i.e. just spinning out of the water) run of the eProp and Torqeedo plus sound level meter. The eProp registered 55dB, the Torqeedo 77dB (from failing memory 24 hours later). Bearing in mind the log scale, that's a big difference.

Serious competition for Torqeedo? Well, in the UK a dealer would help!

[Graham W]

Michael,

I've measured my Torqeedo (in the water but with the sound magnified by the acoustic properties of the outboard well) at around 75dB.  Before Seamark Nunn sorted it out (with advice from Torqeedo in Germany) it was an unbearable 90dB.  Most of the appalling whine has now been silenced, so relatively speaking, I'm much better off.

ePropulsion's 55dB, if genuine, is about the same level as a normal conversation.  Coupled with the eProp's standard big battery, I'd say that Torqeedo finally have a real competitor - if the latter can get distribution and they haven't infringed too many patents.  That can only be good news for the consumer over the next few years.  Torqeedo will have to improve their range, thrust, noise and durability if they want to hold on to their market share.

[Graham W]

I recently bought a 915 Wh battery for my Torqeedo 1003 to give it nearly double the range of the battery that it was supplied with.  The range is still not great at, say, 4 knots (about 8nm in ideal conditions) but there is now less likelihood of being caught out without power.

However, after two recharges the battery wouldn't charge any more, so back it went for warranty repair.  The problem apparently was a failed charge socket on the battery.  There are more wires connected internally to the socket than with the original version because it also has to operate with the supplied USB charge plug.  Yet another example of Torqeedo's poor quality control and lack of robustness.

Meanwhile, the competition finally appears to have a distributor in the UK https://nestawayboats.com/shop/e-propulsion-spirit-1kw-electric-outboard/.  Oddly, they also sell Torqeedo.

I will still use my Mariner 6hp when cruising at sea.

[Antjefokkema]

Well, I have the new Torqueedo with bigger battery on my BRe 63.
It helped us in and out of harbours and through bridges during a whole week before we had to fill the battery again. We have a lot of bridges in The Netherlands but no tides that week.
Speed was sufficient and one very nice thing is that there is absolutely no sound during waiting for bridges.
But the sound it produces on the move is terrible.
One must know that the Torqueedo was build by 2 German guys. One is the plastic technician who did a good job I think. It can be taken apart in 3 parts which makes it very light and also simple to store parts in the boat when you take a walk.
The other guy is the one building the electromotor.
But both of them are not watersporters.
So, we found that the tail is too long. It will not come inside the BRe when tilted. We had to make the tail 8 centimeters shorter. This costed another €200,-
Furthermore, when lowered again, it does not lock automatically. This has to be done by hand, unlike the petrolmoutboards.
So, twice I forgot to lock it and when putting it into work, the whole thing tilted again with a lot of power and damaged the propellor (is that how you call it?) The second time even the break-in broke. We fixed the whole thing with epoxy and a spare breakpen, but the next time it will cost a few hundred again.
And most important,I think the power will not be sufficient on sea. When we don't sail, there will always be headwind. If there is tidal current in addition, the Torqueedo 1003 is not strong enough and does not have enough in the tank for more than half an hour.
So now we are shopping for a Honda 6, which is about the most "silent" one on the market.

[Michael Rogers]

Graham, thanks for the link to Nestaway. I rather liked the tone of their Spiel on-line - interesting that they sell Torqeedo as well, and our prepared to compare and contrast. I note also that they say e-Propulsion have been around for three years 'elsewhere': I wonder whether that's long enough for any patent gremlins to have been sorted!

Re the comments about top speeds, I think this revisits previous discussions about thrust - what it is in this context, and how you measure it. Because a lesser top speed doesn't necessarily mean less oomph for pushing the boat through the water - or does it?

As you say, this does seem to be the competition Torqeedo seriously need.

[Peter Taylor]

So, we found that the tail is too long. It will not come inside the BRe when tilted. We had to make the tail 8 centimeters shorter. This costed another €200,-

Anyone else who wants to shorten the shaft on a Torqeedo please look at "Notes on the Torqeedo Travel 1003S electric Outboard Motor" in the library. Rather than paying €200 you only need a hacksaw and, possibly, a file!
Peter

[Antjefokkema]

Wow, if only I had seen this before! Shortening of the shaft can be done at home! But in case of problems Torqueedo will not replace parts anymore. Guarantee is over then. May be it's worth the risk.

[Graham W]

Wow, if only I had seen this before! Shortening of the shaft can be done at home! But in case of problems Torqueedo will not replace parts anymore. Guarantee is over then. May be it's worth the risk.

There's an alternative to modifying the Torqeedo to make it fit - raise the transom with a hinged piece of wood.  It's described in Addendum 1 towards the bottom of this library article http://www.swallowyachtsassociation.org/?page_id=820.

The type of hinge used is important to make the modification work properly.  Attached a photo of what they look like.  Unfortunately, I can't remember where I bought them.

[Peter Taylor]

I had a look at the epropulsion Spririt outboard at the boat show. From what I could see it does indeed look better than the Torqeedo 1003. With regard to sound it really is quiet - in the Boat Show environment you couldn't hear it running. It also is more responsive to the "throttle" control.  The people there  " www.epropulsion.UK contact: Ricky Cole : rick@epropulsion.uk " are based at Hamble Point Marina and say they will take you out on the water to demonstrate it if you contact them there.

They say it's designed for salt water use - it does have a sacrificial anode. Connecting the battery to the motor is easier than for the Torqeedo and the battery floats if you drop it in the water. Overall it appears better engineered than the Torqeedo. They do say it's made in the same factory in China!

For me, the only downside would be that, unlike the Torqeedo, the Spirit model doesn't have a remote throttle option (which I find useful on my canoe or 15' dinghy since it allows me to sit further forward for better boat trim). You could use a straight tiller extension to control the unit from further forward but that makes steering difficult if you don't have a dinghy style sideways extension too, and the latter is not really practicable with a twist grip throttle control. However most people seem to manage without a remote throttle, so maybe it's just me!

I'll be staying with my 6hp Tohatsu which gives the range and power for sea use. But for an electric outboard, if I didn't already have a Torqeedo, I'd probably choose the epropulsion.

[Graham W]

It might be a good idea to check the epropulsion's length from transom bracket top to skeg bottom before buying.  It looks to have similar dimensions to the Torqeedo 1003 but the (metal!) skeg seems to protrude a bit further down below the end of the propeller.  This might exacerbate the tilting issue in a BayRaider's outboard well - but probably not by much.  Check also how much the back of the battery sticks up in the air with the motor tilted, to ensure that it doesn't get in the way of the tiller.

Interesting that both motors are made in the same factory in China.  The epropulsion one seems to have benefited from the numerous design issues afflicting the Torqeedo - noise, cheap plastic parts, saltwater corrosion, etc.

[Michael Rogers]

Thanks for that interesting report, Peter. I think I might put my decision not to have an electric outboard on hold, at least till next season (that's a sort of double negative, in case it isn't clear). Simple problems like lack of funds remain....

Apart from other features of interest, it does seem to be a technical tour de force to make a half decent battery (and they claim it's more than half decent) which actually FLOATS!

Michael R