Minna Kota Motors

[Ian Loveday]

Sorry to add another outboard motor post but I hoped someone might have some experience of the Minn Kota trolling motors.  I sail mainly at rutland and the slipway/pontoon is in a creek where the wind seems to blow in circles.  I'm looking for something to help with first and last 100 meters of the day.  I have a proper outboard for places that allow it, but unfortunatly Rutland does not.  The Minn Kota motors are 12v and i wouldn't expect much from them but if they make getting on and of the poontoon a bit easer it it would be worth a try.

http://electric-outboard-motors.co.uk/minn-kota-endura.htm

[Johan Ellingsen]

I have a cannibalized 600w MK on my rudder.Works!To get a proper push it needs above half throttle,but mysteriously it doesn't seem to deplete the batteries,much.

[Peter Cockerton]

Ian

For exactly the same reason and location i.e Rutland Waters creek i use a Minn Kota with a 12 ah sealed lead acid battery. Often there are kids enjoying themselves in canoes, small dinghy's rafts etc so sailing onto the pontoon can be worrying.

Used it for three years now and apart from blowing the inline fuse i installed ( 40 amp) when prop gets entangled in weeds its been trouble free.

Plenty of thrust to get my BR 20 moving, very rarely use it on power level 5 (full) but on test in the dustbin i think it ran for 20 mins before safe voltage depletion reached.

Used to get her off the beach as well when comfort break for Scooby (my dog) is called for, he will use the sump if pushed but can't get the hang of the centreboard case slot.

Come to think of it I'm sure i saw an advert in the watersports centre for a Minn Kota.

Peter Cockerton

[Michael Rogers]

TWO threads re electric outboards to peruse?? ....oh well, a bit untidy but not insuperable, I suppose.

I'm becoming increasingly aware of the surprising range of EOBs available, and actually the Minn Kota offerings look quite impressive, if a tad pricey compared with, say, Mariner. I like their fresh/salt water distinction, indicating that they take the challenges of sea use seriously. Incidentally, I wondered whether 'Minn Kota' was Finnish or some such, but apparently they hail from North Dakota.

I wish there was a really thorough comparison available of what's on offer in this area. Any chance of interesting "Which'?!

If anyone comes across new sources of Lithium battery packs, could they flag them up? (TWO threads to choose from.... I suggest we don't start a separate battery one!!)

Michael

(PS In case I sound tetchy, I'm not....... really........Honestly)

[Peter Taylor]

I've had a Minn-Kota RipTide 40 for some years. I used it on my Seafly 15' dinghy before I bought the Torqeedo 1003s. I expected the latter to be a huge improvement but in truth I was disappointed. The Torqeedo wasn't the great increase in thrust that I was expecting and the Torqeedo whines, the Minn-Kota was almost silent. I didn't have corrosion problems with the Minn-Kota, I have had with the Torqeedo.  The main advantage of the Torqeedo was the integrated battery - although I ended up taking a 12V battery along as well to extend the range!

Given that you can't use the full power of the Torqeedo for any reasonable length of time, my conclusion has been that good trolling motors like the Minn-Kota are almost as good (and for some purposes better). But I really don't know how the power actually compares.  If I can find a suitable spring balance I'll try comparing the bollard pull of the two motors using the Seafly.

One problem with 12V trolling motors is they take large currents (several tens amps). Even with a deep discharge leisure battery,  you are discharging it quicker than it likes. That means (a) during a given trip you won't get the rated capacity out of it; (b) the battery won't last as many years.  An (expensive) solution would be to use 12V Lithium-ion batteries which don't mind supplying big currents.  Whatever battery type,  the big currents mean you must have good cables and good connectors. I once melted a connector because, although it was rated for high amps, some hidden corrosion had set in. Fortunately it didn't cause a fire.

Incidentally, the problem with owning a Minn-Kota and a Torqeedo is the sense of rotation of the throttle twist grip (to select forward or reverse) is reversed between the two! Hence I've tended to stick to using the Torqeedo, mainly because it cost me much more money so it has to be better... doesn't it?!

Peter

[Ian Loveday]

Thanks for the feedback folks.  I think I'll give one a try.  I'm not looking for an alternative to a normal outboard but just something to make life a bit easier in Rutland's very sheltered creek

[Michael Rogers]

Peter, do report back on your bollard pull experiment!

[Graham W]

Here's a 2011 American review of Torqeedo motors that goes some way towards explaining why they whine and why they have had problems in the marine environment http://www.sailmagazine.com/boatworks-know-how/electric-horses  Various learned papers estimate that gear whine has to be 15 decibels lower than other noises (such as the sound made by a petrol engine) in order not to be intrusive.  So my measure of 90 decibels from my Torqeedo sounds like 105 decibels because the gear whine is so distinctive.

Here's Drascombe owner Jack O'Keeffe's Torqeedo review which mentions the compromises he makes when using the Torqeedo in his effort to avoid petrol http://afloat.ie/sail/cruising/item/25244-torqeedo-owners-revolt-against-the-petrol-outboard-engine  He won the Highlander Trophy in Sail Caledonia this year by relying entirely on sail and oar throughout and not having any sort of motor or engine.

Apparently Minn Kota trolling motors and similar are much quieter because the motor drives the propeller directly, obviating the need for (miniaturised) reduction gears that cause the Torqeedo's terrible whine.  However, in order to convert the resulting high revs into thrust, trolling motors have to use small-bladed propellers, which are significantly less efficient (and therefore need more battery capacity) than Torqeedo's large-bladed and slower rotating ones. It looks like there are no easy answers......

[Michael Rogers]

Graham, those are two really interesting articles - thanks. The Sail Magazine one is very revealing, and confirms the 'suspicions' you have expressed about Torqeedo learning about corrosion the hard way.

The low revs plus large prop approach is bang in line with the ideas Jeremy (who I hope will finish his eco-house soon so that he can rejoin us) has expounded on this forum and the HBBR one. I would like to know whether there are insuperable problems to designing electric motors which run comfortably and powerfully at low revs rather than having to whizz, because that would seem to be the way to go. It's a bit of a mug's game, surely, to have to fit an inefficient prop to keep an essentially fast-revving motor happy.

In my shuffle towards an electric outboard I'm trying to get my head round one practical issue. When consulted, the sellers of these things seem to recommend the smallest motor which they reckon will push your boat along reasonably well; so for my boat that might be, say, a 40lb thrust version. Given that the difference in price between that and a 55lb thrust version is there but not huge, would it not make sense to get the bigger one and run it well within itself? I need a few graphs of current consumption, revs, thrust, torque (I'm getting beyond myself here!) etc to work out whether that is logical. Any comments, anyone? My front-runner make at present is the new Mariner: the Minn Kota Riptides look good, but are relatively pricey.

In my little boat I'm going to have nothing to do with lead acid batteries, so I'm VERY interested in Lithium pack progress and prices (especially prices).

[Michael Rogers]

Graham, those are two really interesting articles - thanks. The Sail Magazine one is very revealing, and confirms the 'suspicions' you have expressed about Torqeedo learning about corrosion the hard way.

The low revs plus large prop approach is bang in line with the ideas Jeremy (who I hope will finish his eco-house soon so that he can rejoin us) has expounded on this forum and the HBBR one. I would like to know whether there are insuperable problems to designing electric motors which run comfortably and powerfully at low revs rather than having to whizz, because that would seem to be the way to go. It's a bit of a mug's game, surely, to have to fit an inefficient prop to keep an essentially fast-revving motor happy.

In my shuffle towards an electric outboard I'm trying to get my head round one practical issue. When consulted, the sellers of these things seem to recommend the smallest motor which they reckon will push your boat along reasonably well; so for my boat that might be, say, a 40lb thrust version. Given that the difference in price between that and a 55lb thrust version is there but not huge, would it not make sense to get the bigger one and run it well within itself? I need a few graphs of current consumption, revs, thrust, torque (I'm getting beyond myself here!) etc to work out whether that is logical. Any comments, anyone? My front-runner make at present is the new Mariner: the Minn Kota Riptides look good, but are relatively pricey.

In my little boat I'm going to have nothing to do with lead acid batteries, so I'm VERY interested in Lithium pack progress and prices (especially prices).

[Michael Rogers]

I appear to have been repeated. Happy for someone clever to remove one.

[Peter Taylor]

Peter, do report back on your bollard pull experiment!

Out of curiosity I have now tried a bollard pull comparison of the Torqedo 1003S and the Minn-Kota RipTide 40. Both motors were mouted on the stern of my (much neglected) Seafly dinghy which was tethered to the jetty using the orange propylene rope  and electronic balance (as seen in the photos).  I don't know the absolute accuracy of the balance but assume it's good enough for comparison purposes.  The Torqeedo looks odd with battery detached and a remote throttle but, apart from the shaft being shortened by 45mm to fit my BC20, is a standard motor with an almost new propeller. The Lithium-ion battery was reading 99% charge.  The Minn-Kota was powered by a fully charged, fairly new, 100Ah deep-cycle battery connected directly using it's own cable.  The Minn-Kota hadn't been used for a couple of years but showed no sign of any problem.

Once I managed to get a steady pull, which was not easy,  the Torqeedo read 34kg (Practical Boat Owner got 32kg) while the Minn-Kota only managed around 12kg.  The Minn Kota claims 40lb (18kg) thrust.  Torqeedo suggest that figure would be exaggerated by about 50% - which would be in line with my measurements.  In contrast, Torqeedo claim about 31kg for the 1003S , a bit less than I measured.  Thus Torqeedo would suggest 2.5 times the power of the Minn-Kota whereas my test gave more like 2.8. I'm not sure these small differences are significant.

Having the two mounted together was very interesting. The Minn-Kota feels properly engineered with strong transom clamps and a sacrificial anode in the propeller hub.  I'd forgotten just how quiet it is - silent would not be an exaggeration - whereas the Torqeedo whines horribly.  So I was somewhat disappointed that the power ratio was quite so large!  Of course, more powerful trolling motors are available, the Haswing Proturar 2hp tested by PBO had better bollard pull than the 1003S.

Peter

p.s. seeing this posted I'm embarrassed how bad the Seafly looks at the moment... it does clean up, honest!
p.p.s. the comparisons were done at full power - I should have measured the amps going into the Minn-Kota but they claim a 100Ah battery would last 1.5 hours at full power whereas the Torqeedo would only last about 35 minutes. I need to run the Torqeedo at say half power and see what the comparison looks like!

[Graham W]

Peter,

An interesting piece of research!  To give a bit more perspective, it would be good to know how much power the Torqeedo consumes when producing 12kg of pull, the same as your Minn Kota at maximum. It would then be possible to calculate its range and measure noise levels at that speed.

I don't think the motor manufacturers are doing themselves any favours by being weasely about what their products can do.  This is a fair comparison and confirms that Minn Kota's claimed performance exudes a distinct smell of mustelid.

On the other hand, the Torqeedo's whine at anything other than low speeds is difficult to take.  Their claim that you can "talk at normal levels even at top speed" ought to attract the attention of the advertising standards people.

[Michael Rogers]

Thanks for that experiment, Peter! It seems there is something in Torqeedo's rather snooty claim that their measurements of pull/thrust are different from those of other makers. I agree with Graham that these obfuscations are no help to anyone, least of all to potential customers such as myself.

I'm still looking for enlightenment as to whether, for a small light boat such as mine, it is still a good idea to go for a larger engine with more thrust, e.g. 55 lb, rather than a smaller one, e.g. 40lb (I'm talking non-torqeedo-ese here), and get the bigger one to do less work most of the time - which would save battery - albeit with the theoretical capability of being able to push harder for some such task as getting over a fast tide (e.g. the narrows at Teifi) for, say, 20 minutes or so. The bloke from Outboards Direct (purveyors of the new Mariner electric outboards, which are the ones which interest me) explained in his email that the smaller size would push my boat along at 3-4 knots, but that a bigger motor wouldn't improve on this. I suspect that he was thinking of hull speed, and I think Cavatina would have to lift to a plane to go faster than 3-4 knots, but she does that relatively easily. In general I like the idea of a bigger engine working less hard. Am I making sense? There would be a small penalty in terms of a slightly heavier OB and greater cost, but the difference isn't huge.

Michael

[Peter Taylor]

I'm still looking for enlightenment as to whether, for a small light boat such as mine, it is still a good idea to go for a larger engine with more thrust, e.g. 55 lb, rather than a smaller one, e.g. 40lb

Michael, my opinion on that is based on using the 6hp motor on my BC20. Most of the time I use maybe a quarter throttle and Seatern is making a happy 4 knots or so. More throttle will produce 6 knots, vibration, much more noise, much bigger wake, and no doubt much greater fuel consumption. So I don't use it. However if I have to motor in a strong wind or through steep waves I'm very glad I have the extra power available if needed. I'd buy the larger motor even though the smaller one will reach hull speed in calm conditions. The only caveat with regard to an electric outboard would be if the smaller motor is significantly more efficient at a normal boat speed.

Of course, if you are actually thinking of planing under motor you initially need enough power to lift the hull; once planing you can throttle back. The Torqeedo can't quite get my Seafly to plane (and the Seafly planes easily). But I thought we were talking about coming back to a mooring rather than planing across the lake!!!

Graham, I'll try and do the test you suggest, although I can't measure the noise level. I think your Torqeedo my be noisier than mine - the whine is grating on my nerves rather than so loud as to drown conversation.

Peter