Advice needed for someone new to E-boats

brianz

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Apr 17, 2020
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I currently am making a 16 foot sea kayak. It is a pedal drive system that I will use but would like to complement it with a DIY drop in motorized system. ie. torqueedo, bixpy, etc.

I have been doing a lot of research but still can not completely grasp all of the complexities of building an electric drive system. Most of the information out there is related to e-bikes or guys that are just throwing money at overpriced set ups. I have found that most are buying an excessively large a motor and battery which results in excess weight and cost.

Specifically, I am trying to determine the right motor, controller, prop, battery configuration for my boat.

Would anyone be able to offer their expertise on advising me?

I have read and re-read most of the posts on this forum, however most seem to be dated or I may have missed them.

For reference, I am quite "handy" in my build capabilities. While I am new to diy electric, my diy experience is quite extensive... 3d printing, cnc, composites, fiberglass molding, welding, diy lithium batteries... to name a few. This is not to brag but merely a point of reference.
 
What is the pedal drive system on the kayak? Does it have "bicycle style" pedals and thus a "bottom bracket" that could take a mid drive motor normally intended to electrify a bike?
 
Specifically, I am trying to determine the right motor, controller, prop, battery configuration for my boat.
You will need to determine the weight, hull characteristics, desired speed, run duration etc etc..to start with.
There are many old threads on here with folks modding Minkota’s etc on kyaks.
The key points seem to be to ditch the basic speed controls ( just voltage drop resistors) , and use a basic electronic controller for efficiency.
Prop design is also critical if you want good efficiency and max range .. generally , keep the rpm low and use a “aero” type slim (narrow chord) , larger dia prop with the pitch selected for optimum hull speed/efficiency.
Remember , human pedaling is lucky to generate 200W. Of continuous power, so you wont need a big power motor set up to equal anything you can do manually.
As a wild guess, i suspect 8-10 km/hwould be a good target ..( you waste power trying to push too fast)
And a 24v, 20 Ah lithium pack will take you much further than 20Ah of AGM , with a lot less weight.
 
SlowCo said:
What is the pedal drive system on the kayak?
It is a hobie mirage drive. Link below.
I picked it up a used on off eBay. I have already cut the hole for it in the yak but am thinking about changing up the design of the hole a bit and reinforcing it with SS or aluminum to account for the extra thrust and wear and tear of an electric drive.

https://westcoastsailing.net/hobie-mirage-drive-gt-st-fins/?gclid=CjwKCAjwm_P5BRAhEiwAwRzSO-LogMiIhs_cUeUCAWVAIKZAfrqHwYZ1crURkxDa0gt-yS8U2NQiWxoCHSYQAvD_BwE
 
Hillhater said:
Specifically, I am trying to determine the right motor, controller, prop, battery configuration for my boat.
You will need to determine the weight, hull characteristics, desired speed, run duration etc etc..to start with.
I am currently mid-build on the yak with only the base and guts. The top is next. Do I need to wait until she is sea worthy and at the completed weight to test and determine my motor/controller or can I get close. I am trying to work on the motor, controller side in case I may have to order from China and wait for shipping. I am assuming I can work on the prop one I can test drag in the water.
There are many old threads on here with folks modding Minkota’s etc on kyaks.
Not a fan of the Minkota mods. Would prefer doing my own thing. I love learning and buying something stock just isnt my proverbial cup of tea.
Prop design is also critical if you want good efficiency and max range
I am assuming that I can work on prop design after she is built(see above). Is my assumption correct?
Remember , human pedaling is lucky to generate 200W. Of continuous power, so you wont need a big power motor set up to equal anything you can do manually.
As for the range and speed, I just want to use the motor to get me to where I need to go (the fish) and then plan on using the pedal drive when I get there so I can adjust based on currents, wind etc to get on top of the fish. Speed would be nice but not interested in turning it into a speed boat due to increased motor/battery size etc.

And a 24v, 20 Ah lithium pack will take you much further than 20Ah of AGM , with a lot less weight.
I was thinking about a 48v system for efficiency and plan on building a lithium battery out of 18650s. The higher the volts the higher the current so i can run at a more efficient speed with more power because I wont have to run WOT. Am I correct in my understanding?
 
Unless you expect to build something unusually large/heavy/odd shaped,..you should be able to “guesstimate” the weight to get an idea of any exceptional needs.
Just to be clear, you are not planning on adding electric drive to that Hobie Mirage unit ?...but use an additional motor/prop Edirve device ?
Since you are just looking for a simple water drive and are happy to experiment with props/rpm etc after completion, you can just pick a suitable power motor/controller ( <500W) to “engineer” around.
Ignoring the Minnkota type options, there are still many other threads on here with folks constructing their own unique low power Edrives for kyaks and canoes.
48v and current.. ?? I dont think a 48 v system is needed Remember that high rpm props are not necessarily efficient for low speed craft ( it not a planeing speedboat !) and for best power/speed = efficiency that prop design will dictate the rpm range.
I repeat, from what i have seen on previous threads, larger dia, thin chord, low rpm, props are most effective for lightweight , low speed boats. ...but are more prone to weeds and damage !
Here is another thread from a Hobie forum that may interest you..
https://www.hobie.com/forums/viewtopic.php?f=78&t=57709
And this seems very relavent for power/prop selection..
https://www.boatdesign.net/threads/efficient-solar-powered-electric-kayak.52833/
Ignoring the frequent references to Minnkota.. ( they seem very popular tho’?)....
....This ES thread confirms ans sumarises much of the info you may need..
IE:- max speed possible is 5-10 km/h.. more like 5 km/h for efficiency and practical range
200W of power will do it
10x6 or 10X10” 2 blade aero props are good starting points
https://endless-sphere.com/forums/viewtopic.php?f=39&t=100030
 
PREPARING FOR LAUNCH Find a quiet spot in the parking lot away from the launch lane traffic. Some ramps provide lanes to “prep” the boat for the water (“make ready” area).
Remove all tie-downs except the winch hook attached to the bow eye of the boat. Remove any outboard or stern-drive tie-downs or supports. :wink:
boating-etiquette.jpg

Boating, even more so than other sports and activities, has an etiquette, which is defined as “the customary code of polite behavior among members of a particular profession or group.” In boating, etiquette is not only about social norms but also about safety, so it's best to learn a few rules before you untie the dock ...
 
I'm using a couple of Blue Robotic T200 thrusters on my triak.
Voltage is 12-20v but 16v is recommended for continuous use.
Power is 400w at 16v.

They come with an extra prop (left-hand right-hand) and the controller is cheap $35 and tiny (but ordered separately).
It comes with a couple pots and the two motors can be linked in various configurations.

The components are engineered to the lightest weight possible (for ROV applications) and the physical size
of all components is minimal.

The motors run submerged, bearings are water lubricated and everything is salt-water compatible.
No worries of overheating.

They recommend a 4s lithium-ion battery pack.

So there you have it: motor, prop, shaft, controller, battery;
they seem expensive at first until you consider everything you DON'T have to buy.

Installations is a breeze!

I just reread this and it sounds like spam!
I'm not affiliated in any way with Blue Robotics (unfortunately) :roll:

Oops, just noticed this is an old thread that was recently bumped. sorry.
 
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