Trolling Motor & Battery Advice Required

Interesting solution with your swappable blades, SolGato!

I use a single homemade centered post/slotted cup with fingers that cover the only slightly different range of targeted propeller hub diameters and mounts to the propulsion motor shaft. It allows the complete propeller to be instantly exchanged while on the water and so saves a lot of time when I have a multitude of $3-$6 RC model props (pitches and length) to be tested. The unsuitable propellers are not marked in any way by the testing, and can be returned to the Hobby Shop for a refund. The concept might be adapted for the black 2 blade propellers you have pictured and might possibly be tinkered to fit the props with 3 blades, if you will have quite a few to test.

I am a long-time hobbyist of electric propulsion systems in which my goals are a complex balance of highest speed/ longest range balance for the lowest power input, and obtaining the lowest system weight for a 20 mile range. Additional system considerations are lowest draft plus quietness.

My favorite for the highest speed and range balance for the lowest power input in the pic would be the orange propeller (smallest blade shadow drag ?), but my guess is that there is a model prop that tops them all. Also, let me say that there have been some interesting surprises about boat propellor performance as applied to my goals over the years. Though your goals may be different, you might be in for some surprises after your testing is completed, as well!

 

Portacruise-

The orange 2-blade is of course the Torqeedo prop which is the one I plan to test next. I had to drill and ream the shaft hole to fit my motors and still need to modify the shear pin cavity as it is also undersized compared to my motors.

To give you some numbers, that Torqeedo prop is 11.5” in diameter with a pitch of 8.1”.

A typical 3 Blade performance trolling motor prop is about 10.875” x 5”.

And a typical Minn Kota 2-Blade is about 10” x 4”.

The Torqeedo prop as you can see is quite aggressive compared to the others. This is because it’s the standard prop for their original planetary gear driven 1003 Model 1KW input/480W output motors.

When you compare the specs of that prop to what they are using on their new 1103 Model Brushless direct drive motor you see that they had to change to a smaller prop with less pitch. That prop for the 1101, which is a 1100W input/520W output motor, is a 10.2” diameter x 6.2” pitch 2-blade.

Anyway, since you’re into props and have an understanding of how their design affects performance, check out this handy chart of all Torqeedo’s offerings.

Studying the various pitches and diameters and what they are recommended for (weedless, planing, etc..) and the application motor size wise, you can get a feel for how they match a prop to their motor controllers.

Now I have a hunch this prop I modified may be too much for my motor, but I got a great deal on it so I figured I might as well experiment. Plus one of my motor controllers is defective and I have a replacement that I’ll install eventually, so if I damage it during testing I’m okay with it.

I’m thinking just based on comps, that their 1101 2-blade might be a better match, although my motors are more powerful at 1470W input/1000W output each.

No doubt the RC Model hobby has developed a plethora of props to choose from making it easier to experiment.

Have you tried any of the adjustable pitch versions with the hub that accepts toothed blades that are indexable for varying the pitch?

 

From SolGato:
"Now I have a hunch this prop I modified may be too much for my motor, but I got a great deal on it so I figured I might as well experiment. Plus one of my motor controllers is defective and I have a replacement that I’ll install eventually, so if I damage it during testing I’m okay with it."

PC: Depends on the torque and RPM that your motors are running, but if you have an amp meter, you should be able to monitor the amps while you play with the throttle to keep it below the critical range were the controller Burns. I think most of the smaller MK run at 1200 RPM under load, don't know if the larger Motors you are running would be similar? If the torquedo blade is too aggressive in Pitch, it won't produce a better speed at that amp limit (or lower) compared to the props you are currently running. From your previous pictures, I assume you are running the three blade performance props at the present time?

"I’m thinking just based on comps, that their 1101 2-blade might be a better match, although my motors are more powerful at 1470W input/1000W output each."

PC: I agree, but would that keep you within the 70% throttle range for the PWM, is the other requirement?


"No doubt the RC Model hobby has developed a plethora of props to choose from making it easier to experiment."

PC: The apc props are fairly cheap and easy to alter to get a fit with the MK, too bad a Reverse pitch is needed for the MK, which means very limited choices.

Products Archive | APC Propellers https://www.apcprop.com/shop/?product_cat=pusher-for-ic-engines

10x8p, 12x6p or 13x6p might be good choices to try, but the unavailable wide blades seem to work better in water.

"Have you tried any of the adjustable pitch versions with the hub that accepts toothed blades that are indexable for varying the pitch?"

PC: Nope, and I haven't seen those around for quite a while, maybe they are available overseas? They weren't within the size limits for my particular application, and didn't look to be as efficient as a properly sorted (tested under operating conditions) prop blade...

Hope this helps.

 

EPropulsion has a few prop options that may be better suited for experimenting with standard trolling motors. Still waiting to hear back from Haswig about their new 3-Blade, but the Spirit 1kw EPropulsion motor uses a 2-blade that measures 11” x 5.8”.

That falls somewhere between the standard 2-blade Torqeedo uses on their similar sized planetary gear driven motors which is 11.5” x 8.1” (which I hope to test this weekend), and the prop they use on their brushed motor which measures 10.2” x 6.2”.

Looks like I’ll be purchasing a EPropulsion Spirit Plus motor to use on my de-rigged Hobie Wave Catamaran that I plan to use this season as a tender to get to and from my Trimaran on mooring.

Our main access road to the Bay I moor in had a landslide which has created a lot of traffic issues, so I’m rigging up my Wave with a bimini top and the Spirit motor. If it works as well as I suspect it to, I will likely build a rigid bimini with 330-440W of solar to keep the Spirits built in battery charged.

Lots of great design features built into these motors, including the ability to handle up to 40A of charge current while under way! With the built in battery having a capacity of almost 30ah, that means you could recharge in less than an hour and run purely off the sun while still replenishing the battery if you had enough solar.

 

Sorry for the bump, I know it is old thread.

Your 2x posts here are really informative for kayaking... I have 2x of Minn Kota 30#... Would you please link me the prop you used to get a bit more range/speed?

 

You can mount the standard APC prop "backwards" (cut a slot for the breaking pin in the front), and when needed use the reverse direction of the motor as your forward. Thats how I do it with my caroute motor and a 12x6 APC prop. It works OK. I can't break the prop with my 700 Watt motor, but it bends considerably at full power.

Greetings, Hans

 

If you are using two trolling motors on a kayak mounted on the same line, better control to be had, if the props are counter rotating.

Ps. The approximate range for RC props is between 10 x 6 and 12 x6 ( around +1or-1 on both measures) depending upon how efficient your kayak Hull and total payload weight / highest cruising speed is, some experimentation is required to pinpoint the best graduation needed.
Hope this helps.

 

Hi!
RC props have a foil shape and the Leading Edge of rotation should be the thicker part of the foil for best efficiency when used as an air propeller, as I understand it. RC propellers will also work with the sharp/ thinner Edge leading, when used in water, but may not be as efficient; my measurements indicate a greater torque is required to achieve the same boat speed. The motor spin Direction will be reversed when running a Troll Motor switch in the backup Direction ( but sometimes full backup 100% power is not available, for safety reasons) which will accommodate the larger availability of tractor props. There are also other more time consuming ways to change the motor shaft rotation direction to accommodate tractor props.

Hope this helps.

 

Thanks much for the replies! I will take a look further.

 

Since this thread was resurrected, I thought I would provide an update on my current prop setup.

I ended up testing the Torqeedo 1917 against an almost identically sized/pitched 2-Blade that Caroute began offering for their motors for use on light displacement applications.

Since my boat is a Catamaran with dual motors each mounted directly to the stern of a hull, and since I use the independent thrust of each for differential full steering control, it’s the perfect platform for testing/pitting props against each other as the better prop will steer the boat in the opposite direction overtaking the other.

Interestingly the Torqeedo prop significantly outperformed the Caroute prop providing higher speeds, more bite and response, and more efficient cruising speeds.

What’s the difference you ask?

Well, after studying the two side by side, I have chalked it up to a difference in materials -the Torqeedo is heavier and made of more dense and ridged FRP, where’s the Caroute is softer and more plastic-y, so I suspect there is some deflection under load with the Caroute prop.

Also, the blade chord of the Torqeedo and the profile of the blades and the twist at their tips seem to also be playing a role in the significant different in performance.

So after discovering this, I picked up a second Torqeedo 1917 and modified it to fit the second motor, and now I’m running a pair of them.

Once I decided on them, I rewired my potentiometers on my remote since they are designed to spin in the opposite direction.

The next mod I did after settling on the Torqeedo props was to raise my motor mounts a bit to run the props closer to the surface, and add remote trim control for each motor.

The results were an increase in top speed to 9MPH, the ability to cruise at a higher speed on solar only, more responsive steering, and the boat being lifted a bit more out of the water.

The only real drawback is less maneuverability in reverse and super slow speed responsiveness compared to the original small 3-blade trolling style props, and a larger wake at speed.

Most importantly, the motors are not exceeding their max Amp draw under load with the Torqeedo props since my boat is lightweight and semi-planing.

I may still try the 3-blade 1901 Torqeedo prop to see how it compares if I get my hands on one.

 

Wow, very nice innovations and design, particularly impressive is the automated control of each motor! Looks like it might work in open water, if it's not too rough? How far have you ridden it?

Thanks for posting the videos, it brought back wonderful memories! We've ridden a tour on that same Kauai beautiful River that took us to a hike to Wailua falls, a few decades ago!

I love lush jungle type cruises, I just did a 4 Mile one this past January in Puerto Rico of the Sabana River and another preserve- using my pack in, one man, e-boat I did not use the solar powered part because the rivers have an interfering canopy of vegetation, & bamboo in some places, plus I had to stay on the shady side away from the occasional falling coconuts, haha..

Cheers!

 

Thanks!

Yes, Wailua river and the falls are pretty scenic. And Hollywood must agree because the location has been used in a number of films, most recently Disney’s Jungle Cruise. It’s always fun to go up the river after watching a movie to spot the locations they used.

You may have noticed at the end of the second video I did a cruise by the Smith Family barges that they use to shuffle people up to Fern Grotto. One of my last cruises up river I tied up to the dock and the barge operators were hanging out while the tour group was up at the Grotto and they were tripping out on my boat. I told them they could do the same thing with their barges which have full length/width tops on them that they could easily mount a bunch of solar on. They are really behind the times with the diesel pushers they use to run their barges, and they seemed pretty receptive. Most of the time their barges are sitting tied up to the dock under full sun, and most of the river is exposed, so it makes sense for them. Seems like every time I’m down there they are refurbishing one of their pusher tugs. And when you get stuck behind one with their stacks billowing smoke it’s pretty obnoxious.

Anyway, yes the electric remote trim works great. I had always intended to incorporate linear actuators and had designed the motor mounts around the plan, but had been using them manually for the last few years. After hitting a couple of water logged coconuts and getting caught in a “running of the logs” incident when I was surprised by a flash flood up river one day, I decided it was time to install the actuators, especially considering the cost and extra work involved in modifying and installing the Torqeedo props. Of course trim also comes in handy when beaching and especially when navigating the fingers of our rivers as far up as I can until they transition into rocky streams. It’s also incredibly responsive when trimming under way, more so than my old Chris Craft Cigarette, and it really helps when heading into wind and chop as the wind has a tendency to get under the trampolines and solar top and lifting the bow causing mild porpoising.

During our summer mooring season I use SolGato as my tender to get out to my Trimaran when moored in Hanalei Bay. It works well in the Ocean although it is very buoyant and reactive to swell since it rides the surface of the water. The better bite of the Torqeedo props helps keep the boat better pointed a with less energy wasted staying on course versus the previous props I’ve used. I don’t get too far out there when we have rolling swell mainly because the seating is still mesh trampoline so it can be a wet boat in those conditions.

I haven’t done any long distance trips with the boat as I never designed or intended for it to be used in that way. Typically I have a destination I get to, then I drop the built in anchor and relax while the batteries recharge. Once I finish up the lateen/crab claw sail rig I designed for the boat, I will probably have a go at making the trip around the bend and back from Hanalei to the Napali Coast just for fun and as the ultimate design goal for the boat the way it is currently configured. I’ll use the sail for the downwind leg, and the motors to get back.

Otherwise, I don’t really plan on making any more changes to the boat except for possibly swapping the motors out for 1.5kW/160lbs thrust versions and moving the current 1kW/120lbs thrust setup over to my Trimaran. If I do that, I will more than likely have a go at using a pair of the 3 blade 1901 props with the bigger motors which also reach a higher RPM than my current pair.

Anyway, I’m also just starting on building a new 30’ Solar Electric Sailing Cat based on all that I have designed and learned on/with SolGato. That boat will be much drier and capable of open ocean cruising and will have the room for a large battery bank and be an appropriate platform for a pair of much larger electric motors. The plan includes a pair of inboard brushless motors coupled to a pair of outboard like legs much like a sail drive in order to maintain shallow water navigation ability, beaching, trailering and river launching. It will also feature a telescoping beam system with internal linear actuators that will allow it to expand on water from a 9’ trailering width to 14’.

Your river adventure sounds like fun! I have considered building another solar electric boat and shipping it over to Amsterdam just to cruise around their canals and then leave behind for sale. My friend rented a little boat with a trolling motor a few years back and said it was fun exploring by water. Being that I spend most of my time boating to secluded jungle like destinations, the idea of cruising around a city with canals and being able to stop for a coffee or beer is my idea of a vacation

 

Some comments inserted in your message above @ PC: