Not a bad choice. The Motenergy motors have a proven track record as small boat propulsion motors and service from the mfgr is pretty darn good. John at Motenergy was quick to help me out with a bidirectional fan when I realized that switching from reduction drive to direct drive makes the motor turn the wrong way for optimum cooling. The Sevcon controller that comes with the kit is highly regarded. However I understand that you need special equipment to change the software configuration. The Kelly controllers are easily configured by the user. Some people are perfectly happy with the way the Sevcon controller comes pre configured and don't really want to tinker with such minutae anyway, though. The ME1305 motor is an updated version of the ME0907 and so the stated RPM/volts constant of 50 is actually probably 67 but details details. Ask about the Curtis bidirectional throttle. If I understand correctly it works like an EOT, i.e. center position is stop, one way is FWD with speed depending on how far from center you move it, and the other way is REV in similar fashion. This is a lot easier and intuitive than a separate reversing switch. If you are up to the task of experimenting with your reduction ratio, get a belt type reduction gear or fabricate one yourself, so you can change ratio by swapping out a pulley or both pulleys. Thunderstruck's reduction gear looks a bit flimsy to me but then again I overbuild everything. The cables in the kit look a bit smaller than I like. I favor 2/0 cable for supply and phase cables. No biggie if it is truly to be used as auxiliary power and not all the time like some "sailors". All Electronics sometimes has some nice bit heat sinks that would work for the controller. You will want a charger of course, and probably a 48v inverter (get a sine wave type... they are getting a lot cheaper these days) and a DC/DC converter for 12v loads. Even if you keep your old house bank, it is good to have a redundant source of 12v power, but if you choose to let your house batts die a peaceful death from old age without replacing them, you get some weight and space back when you eventually remove them.
Don't forget an instrument panel. You will want to keep an eye on controller supply current and voltage, and watthours used, and propellor RPM. Lots of all in one digital power meters on ebay and hall effect digital tachometers as well, so you can do an instrument panel pretty cheap. There are even some dandy little GPS speedometers that you can incorporate into the panel so you can log SOG along with volts, amps, watts, and RPM. Optimizing the reduction ratio and/or prop size is very data intensive. Speed monitoring is therefore very important, and you need more accuracy than your smartphone and more convenience than a chart plotter or laptop for this.
---In electricboats@yahoogroups.com, <mryanqld@...> wrote :
On Mon, Jan 15, 2018 at 1:37 PM, Michael Ryan <mryanqld@...> wrote:Although the QS 6000W motor I priced is designed for use on a small car and not a ebike type I am reconsidering this option. Their are questions about their durability and to go for a conventional proved motor is good advice. The design and fabrication of a thrust limiter or reduction drive system for me is not a problem as I have a mechanical background but only starting to get my head around the electrical side. I can see some advantages of indirect drive, proven components, no thrust on the motor, ratio's can be very easily changed, lifts the motor higher. The only disadvantage is power loss.Regarding correct prop size, on a previous heavy displacement sailboat fitted with a 30hp Yanmar the theoretical hull speed was about 7..2 kts. Full engine RPM flat out in calm water with no wind resulted in a wave forming at the transom and a noticeable squatting down in the stern. The engine was also loaded up and starting to blow black smoke. I believe that this boat had the optimum engine/propeller for it. The squatting down and stern wave is the boat trying to get up on the plane which is obviously not going to happen. Backing the throttle of 50% only reduced the speed to 5.5 kts.The Nordic 17 based on a waterline lenght of 16 feet will have a theoretical hull speed of about 5.1 kts. I suspect the sweet spot for this hull will be around 4.5 kts.--On Mon, Jan 15, 2018 at 5:58 AM, Matthew Geier matthew@acfr..usyd.edu.au [electricboats] <electricboats@yahoogroups.com > wrote:
I have 'electrifed' a similar Nordic double ender - a project that
probably inspired 'mryanqld'. These boats need very little power - I've
found that the 'sweet spot' cruising speed for my hull, the system is
running only at 1500w.. I can wind the power up more, but little extra
speed is gained for the extra power, the boat just starts to pull a
bigger wave behind it.
I'm using the orginal prop that was on the boat when it used to have a
5.7hp two cylinder, two stroke 'Blaxland'. I believe the prop is the one
that came with the original Blaxland engine and designed for the high
torque two stroke. Certainly back in the 'stink pot' era when the clutch
started to wear I'd had the clutch slip instead of the prop cavitating
when the boat was under load (lots of teens hanging of the back wanting
to be towed through the water!)
I direct drive a Perm 132, although when my Trojan's finally give up, I
may go to 48v and put a 2:1 reduction on it, the higher voltage will
lower the current and the heat losses. (But the new gearbox losses may
be higher than my current heat losses :-)
Kind regards Mick 0414 264 312--Kind regards Mick 0414 264 312
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