Electric Paddle Drive 2hp Review

[ecgossett]

Electric Paddle Drive 2hp Review - Try it!

 

The Electric Paddle Drive 2hp (EPD2) outboard is a  power head mounted direct current motor, that can provide 34 pounds of thrust at 245 watts an hour for 2 hours and will be comparible in price to a 2.5hp gas outboard.

 

I had a chance to try the EPD2 outboard at the NW Wooden Boatshow on my Core Sound 17. The boat weights about 390 lbs, and we had three large adults in the boat averaging about 600 pounds. Overall the boat weight was right around 1000lbs. Average speed was 3.5knots with bursts to 4knots.

 

At first glance the outboard is small and brings back memories of my 1957 Elgin for size. The battery back is in a seperate mountable bag, which with extender cords Electric Paddle can provide, could sit anywhere in the boat. The prop is similiar to an RC prop, and large mazimizing the efficiency of electric low speed, while not trying to copy a conventional outboard drive prop like some electric outboards do.

 

It was super light, and the only touchy part was mounting the $20k prototype with out dropping it.

 

Peukert Law

Ragone plot

 

Details from Electric Paddle:

Motor:

• Power input- 250-300 watts- exact value tbd

• Motor operates on 24 volts with an option for 36 volts

• Power is variable digitally as the knob is turned in so many steps it's considered continuous

• 24 volt input peak efficiency 50%- electrical watts in/ thrust x speed in watts out.

• Electronic reverse

• Safe start delay and ramp with safety switch

• Tilt up and down, power, and safety switch all controlled from the handle at the end of the longest tiller arm in the business so you don't need to lean.

• Available in short and long shaft length

• Motor has our patented gear/bearing/propeller module with a high aspect ratio, 13 inch disk area, final pitch options still tbd.

• Motor weight between 12 and 13.5 lb tbd

• Motor is designed to be waterproof to survive a swamped or capsize situation.

• Speeds on specific boats will be provided as we test.  So far, a 7.5 ft Eastport pram goes 3.5 knots.  9 ft Minto 4k, 14 ft day sailor 4.3k, a pigmy osprey is 5.2 all in knots.

Battery is a 24 volt unit from k2 energy.  Any 24 v system is acceptable, from direct solar to lead acid etc.  k2 specs are available at their store:

http://store.peakbattery.com/k224vlfpba.html

 

Together, the system gives 45+ minutes of runtime at full speed and extending the range with lithium is much less expensive than torqeedo.

More specs and features will come out as the design settles in the next few months.

[ricknriver]

Hi, Many thanks for the information and pics.  I'm contemplating electric for my CS15 for the "quiet".  How does the EPD2 compare in noise with Torqueedo 1003 (a bit "winy") and an equivalent thrust trolling motor Motor guide or Minnkota , if you have had a chance to try them all?  Tks again.  Rick

[ecgossett]

Very quiet rumble.. No wine. Sort of like our electric inboard but much quieter... Really more of a hum that is quieter than the crinkling of sails.

 

I've tried the Torqueedo's including at boatshow this year (west marine let me). I've used a trolling motor on a different boat.

 

Torqueedo is louder because it's putting out more thrust, and instant torque.

[Randy Jones]

Rick,

I've played around with a couple electric motors on my CS17, here's what I found.

 

1. A traditional smaller Minnkota electric trolling motor gave top speed of something like 2.5 to 3 knots with 19Amp draw on a 12V battery.  This gave me about a 2 hour battery life on a 42lb, 55 Amp Hour battery.  A CS15 should do a little better.  These motors are inexpensive but not terribly efficient, end result is limited range.  If you are just going out to noodle around it might be all you need.

 

2.  Offered up my boat for electric paddle testing using different propellers a few years ago .  Efficiency is dramatically better then the standard trolling motor. I think the power draw was about half and of course they pair it with an amazing small battery.  I think you'd get pretty good range if you combined one of these motors with a larger on board battery. 

 

3.  Haven't tried torqueedo.  depending upon model it could offer higher peak power output and of course their display provides continuous info on remaining range at current speed. Seems you'd need a spare battery or an on board battery for extended range.

 

I think it comes down to budget, your appetite for technology, and your level of what electric car owners call "range anxiety" .

[ecgossett]

I think range anxiety could be fixed with having a standby battery bank you could put in the boat for those "longer" journey's. 

 

I ran some numbers the other day using a http://www.amazon.com/DEEPCYCLE-SOLAR-ENERGY-STORAGE-BATTERY/dp/B008D5YG3Gwhich weights 23.5lbs and 35ah of energy.

 

1) 24v 70ah setup: 2.65-3.35 hours to half charge at 250-300 watts. Roughly 10amps an hour.

2) 36v 105ah setup: 5-6 hours to half charge at 250-300 watts. The higher voltage and 3 batteries makes the Peukert formula much cooler.

 

Now couple this with a 100-200 watts of solar panels, and planning on normally sailing your range is unknown. I'm happy to send the excel file to anyone who wants it.

 

If you wanted to spend money, throw in lithium batteries for at least half the weight (cheaper lithium), and consider doubling your ah's available.. Of course I think that is way overkill for a small boat.

 

 

For discussions sake we should all use watt-hours which is energy capacity. AH are measured in current capacity, which does not translate between different methods of storage. That is why peukert formula exists for lead acid, but doesn't work on lithium. 

 

The equation for power is
watts = amps x volts
and for energy the equation is
watt-hours = amp-hours x volts

[ricknriver]

Many thanks Randy and Edward for the information.  Soon as our eastern seaboard soggy weather subsides going to experiment a bit.  Will let you know what I discover on the CS15 and the Amanda we're building.  Would like to make the Amanda a little "electric explorer" having more, stability as we age, than our solo canoes especially in FL gator waters where we love to explore in winter months. 

 

Randy, Hope you're enjoying the BH19.  Safe sailing, Rick

[Soundboats]

Nice little motor.  And, I would like to ditto some of the other comments.  

 

The critical factor in range is the power consumption of the motor and the storage capacity of the battery(ies).  The watt-hrs stored (energy capacity) will determine the range at any specific power draw. Lead acid batteries, whether flooded or AGM, 2V, 6V, 12V or 24V, will store 17-20 watt-hrs per lb. Lithium batteries store about 46 watt-hrs per lb.  With a motor drawing 300 watts you would need about 35 lbs of lead acid batteries for ever hr of cruising (300/17 = 17 lbs, but the lead acid battery should not be drawn below 50% capacity so that means a battery of about 35 lbs).  You would need only about 8 lbs of lithium batteries for that one hour of cruising because lithiums can be drawn down to 10% of capacity without degrading their life span. 

 

A comment about efficiency.  The critical factor in the efficiency of power transfer from prop to water is rpms and the pitch of the prop.  Slow rpms where the pitch is about equal to the diameter provide the most efficiency.  Most DC electric motors have a very similar efficiency of about 85 - 90%.  The advantage of electric motors is that their curves of torque vs rpm are almost flat.  That means the motor will put out its maximum power output based only on the current and voltage you are putting through - not on the rpms.  So the big difference in efficiency between all of the electric propulsion systems is prop size and rpm. The Torqueedo has a 12" prop whereas the larger trolling motors have a 10" prop, so yes the Torqueedo is more efficient than trolling motors. 

 

However, in my experience the difference in price is not worth the slight loss of efficiency.  As best as I can figure the Torqueedo prop has an efficiency of about 80%. This means that there is 20% slippage.  Under ideal conditions a prop with a 10 inch pitch should move forward in the water 10 in for every revolution.  An 80% efficiency means it actually moves forward only 8 inches in the water.  My first electric boat was an inboard with a 16 " diameter prop with a 16" pitch.  Hull speed was reached at 600 rpm and under these conditions my efficiency was 85%.

 

Now I use two 36 volt trolling motors with 10" diameter props and I estimate my efficiency to be about 75% at hull speed (5.1 knots).  So actually I am losing only 5% in efficiency by using the trolling motors instead of a Torqueedo.  Trolling motors are designed to move big boats at low speed, so inherently they are fairly efficient at low speeds, and the Torqueedo can't do much to improve on that. 

 

Also, note that the power required to move a boat is independent of the motor used.  It takes about 700 watts of power to move 1000 lbs of boat at hull speed under ideal conditions.  If my prop is 75% efficient (and the DC motor is 90% efficient) I actually need about 1030 watts.  If my prop is 80% efficient (and the DC motor is 90% efficient)  I would need only 970 watts.  Based on my experience over 20 years of electric cruising, the amount of energy used also depends of how much slower than hull speed one is going.  If I were satisfied with going at 1/2 hull speed (2.5 knots for me) I would only used 1/4 -1/3 of the power needed for hull speed (about 200 watts/ 1000 lbs displacement).  These numbers however, apply only to a displacement hull.  A small boat with a planing or semi-planing hull would have different numbers. 

 

Tom 

[IsZataRock]

Great thread, guys!  I've been considering alternatives to my big, heavy, NOISY 6 hp but have had trouble finding useful numbers to figure out my options.

 

I did a few conversions and found that Tom's boat, a 1000-lb displacement hull requires about 61 lb thrust to go 5 knots in good conditions.  (Did I do the numbers right? 700 W = 513 ft-lb/sec.  5 knots = 8.4 ft/sec. 513 ft-lb/sec / 8.4 ft/sec = 61 lb.  Don't ya love SI units?)  That's the kind of thrust we get from the larger trolling motors.  And it passes my limited sanity test of what we might expect in performance.

 

It's tricky to estimate a boat's power requirement as a function of speed.  So perhaps it fits that Edward's boat (also 1000 lbs though perhaps a little longer) which got 3.5 knots with only 34 lbs of thrust (that's only 200 watts output power).  I was thinking even 40 lbs of thrust would be too small for a CS17.

 

Maybe the crux question is how much thrust is needed under ADVERSE conditions?  I'm thinking narrow channel with headwind, chop, and ebb tide.  ARRGH!

 

In terms of cruising endurance, it's hard to compete with a noisy outboard if you want to be sure to get somewhere.  But even on a multiday trip done mostly under sail, I wonder about how an electric would work.  I haven't figured out any good way to mount solar panels on my CS17.3.  I was thinking about buying a 900 watt "camping" generator.  It can't be any worse than my 6 hp.

 

Hal

[ricknriver]

Great to see others joining this thread and appreciate all the inputs.   I've been listening to electric paddle and other tests and reviews on YouTube.  I found the elec paddle (and Torquedo) pretty noisy (winey).  The trolling motors still seem a good bit quieter (my big issue).  I'm trying to figure if a 40# thrust running at higher speed would be more efficient (longer running on same batt at same boat speed)  than a 55# thrust running at a slower speed? Works for gassers :-). Sent a note to MinnKota but never responded.  Trying to stay 12v lithium for space and weight.  Would still carry the Honda 2.3 in the truck if more of an open water trip or with probable strong tide/current. Too much figuring & decisions. My brain hurts. Think I'll watch the ducks in my very flooded yard.  R

[Soundboats]

Hal,

I have found that using the lbs of thrust rating on outboards is useful only for comparisons between trolling motors.  The thrust advertised is measured with the boat pulling against a spring balance tied to the dock.  It has little to do with the actual power under way since your prop is 0% efficient; it is not moving forward. 

 

If possible you need to measure the power being consumed by the trolling motor by measuring the current and the voltage at any one time.  

A 10 amp current at 12 volts = 120 watts.  If you run that way for an hour you will have consumed 120 watt-hrs of energy.  

 

There does seem to be something wrong with your power equation.  Let us say you are traveling at one knot using 513 ft-lbs/sec.  This means you are traveling at 1.7ft/sec.  Your equation would then give 513/1.7 = 301 lbs.  So I don't think you can do the calculation the way you have.  It just came out looking right using the numbers you had.  I would stick with watts.  You should be able to determine the maximum current used by a motor from the manufacturer's specs.  The volts of the battery pack x max current = maximum power available to you in watts. 

 

Here are the numbers for my boat - A 26 ft St. Pierre dory with a 20ft water line.  I have two 36 volt trolling motors are rated at 105 lbs of thrust.  At my hull speed each motor is consuming 1200 watts of power.    The boat and occupants weigh about 3000 lbs, so I am using about 800 watts per 1000 lbs of displacement to reach hull speed.  This is actual power consumption including the losses in efficiency in the motor and the prop. 

 

My boat is strictly power, no sails.  I originally had 12 golf cart batteries that gave me a range of about 20 nautical miles.  I replaced them with lithium iron phosphate batteries and increased my range to 60 nautical miles within the same battery boxes (and lost 150 lbs of weight) 

 

Rick,

Yes the trolling motors are much quieter than the electric outboards because the motor is underwater rather than on top of the power train.  The other advantage of the trolling motors is that I separated the controls from the shaft.  I mounted the motors and shaft on the outside of my hull on pivots and wired the controls next to the tiller in the cockpit.  

 

With regard to a 40# or 55# thrust motor - the actual difference in power consumption by the motors will be very little because the efficiency of the DC is steady across the full range of rpms.  However, Your 55# thrust motor will probably have a larger prop (bigger pitch) and be turning more slowly so it will have a slight edge in the efficiency of the prop.  So you may gain 5-10% in efficiency depending on the differences in the prop pitch and diameter.  The larger motor will also give you a bigger margin of safety in case you get head winds.  Head winds are like adding weight to your boat since they are expressed as resistance above the water, not resistance in the water.  So the additional power can help.  Currents however are expressed in the water.   If either the 40# or 55# motors will get you to hull speed then there is no difference between them.  Neither motor will be strong enough to get you above hull speed in a displacement hull.  You will be moving at hull speed - current speed regardless. 

 

Tom