Engine Hacks: Electric drill made into a trolling motor

We knew our engine hacks theme would come down to an argument over the difference between “a motor” and “an engine” so after much deliberation, name calling, restraining orders, and a duel we’re happy to put up [Berto]‘s DIY trolling motor made out of an electric drill. The project is probably inspired by [Berto]‘s collapsible amphibious e-scooter that used the same electric drill propulsion setup.

The build is just a few pieces of wood, drill rod, some hardware and a prop. Definitely not the most complicated build. This isn’t the speediest motor ever when attached to a canoe, and isn’t meant to be a primary means of propulsion. That’s not a problem for this build – trolling motors aren’t designed to be fast or powerful. There’s no word on how much thrust [Berto]‘s motor can put out, but it is a nice bit of MacGyverism to build a boat motor out of spare parts.

Check out the build walk though video after the break to see the motor in action.


  1. Graham says:


    But seriously, this is interesting but not something I would have ever thought of to use a battery powered drill for. I give the guy props for ingenuity! Would be interesting to see what he gets on a single charge.

  2. zzzomb says:

    I tried using a cordless drill on both a bike and as a steering servo retrofit to a kid’s electric ride on car. These motors have ample torque for these purposes. The downside is that the drill chuck constantly undoes itself. There is no way to make them stop from wobbling themself loose no matter how tight you attach them. The only solution i found was to weld chuck permanently to the drive shaft. On the plus side, you can afford to permanently devote a cordless drill to these types of purposes cause they are so cheap.

    • Dax says:

      The downside being, that because they are so cheap they’re not designed to be run continuously.

      So you have to replace the whole drill a few hours in use after you permanently welded it to the shaft.

    • Max Allan says:

      Ah yes, that’s why you should never use a Jacobs style chuck in a milling operation. It doesn’t matter how much you tighten it, it will come undone.
      Rather than welding it in place, you could have drilled across the shaft and through the side of the chuck to accept a pin. That would have allowed for some motion of the shaft but still kept them rotating together and been removable.

      I don’t know how the original project keeps the prop on the end, it’s another drill chuck which looks to me like it should unwind.

  3. Sebastian says:

    How about some really really powerful drill + a decent set of batteries with solar panels. Just leave it wherever and it reloads the batteries and off you go again. :)

    • Dax says:

      I once calculated how much it would take to power a proper outboard electric motor, and it was a bit too cumbersome.

      It takes about 200 W to run the motor, so for 8 hours you need 140-150 Ah of batteries. That in itself isn’t really a problem, it’s just a bit heavy.

      But the solar panels are. You get about 100 W per square meter when the panel is aimed at the sun. If it’s fixed to the midday sun, your daily coefficient of power is approximately 10%. That means you get 24h x 100 W/sq-m x 10% every day.

      That means for every 3 by 3 feet solar panel, you can only collect about one hour (200Wh) of driving each day. You need eight panels to recharge the entire battery in a day, but that would be impossible to carry along in your boat.

      You simply can’t take a small boat, possibly a canoe, and put a rack of 8 sq-m of paneling on it, with pivots to aim it properly. It would look like a sailboat with sails made out of solar panels.

    • Dax says:

      It is very surprising how little solar panels actually produce. For example, the photovoltaics in Germany, installed under government subsidies, are only producing around 7% of their nominal on average.

      That’s because half of the day is actually night, and on the other half the panels are aimed somewhere else than the sun, except for couple hours in the middle, and then it might be cloudy.

      • Galane says:

        I’ve seen pictures of one of those solar plants in Germany. The panels were mounted too low to the ground to mow under them (should have put down weed barrier and gravel), the weeds were growing high and shading the panels and they were mounted at a fixed angle instead of on sun tracking mounts.

        The company ripped off the government big time then abandoned the facility.

      • Galane says:

        It needs something like a plastic cup on the front side of the prop, fitted around the drill chuck, to streamline the prop hub a bit.

        There’s a lot of power being lost to the drag on the prop hub’s cup shape.

        Alternate option, a flat disk placed over the hollow front of the prop hub would reduce the drag.

  4. killerbug666 says:

    You could always get a small generator and use it only for extending range…it would still qualify as an electric vehicle by the standards of every manufacturer out there…and if it is just a small fishing boat, you can charge it up at home from some nice, earth-friendly, coal burning power plant from 50 years ago with no emission controls.

    • Dax says:

      Been there, done that. :)

      Hooked up a 1 HP gasoline powered water pump engine to a car alternator. Instant hybrid boat. It was notoriously inefficient though – and the engine was too noisy.

  5. Japala says:

    Tried something similar back in -07. The original engine was dead on the outboard so I ripped it out to test if the drill could give enough power to move the boat.

  6. karl says:

    Nice concept, but it looks like something they would do on the Brittish version of “Top Gear”

  7. ironring says:

    Very clever idea, but I wonder how long the drill would be able to stand up to the abuse that it would receive, plus the high duty-cycle (e.g. on for very long periods) operation.

    (to add my two cents to the motor vs engine debate, if it isn’t converting potential energy from the flow of heat into kinetic energy, it isn’t an engine)

  8. planetjay says:

    I missed the duel? Damn.

  9. wardy says:

    How about just using a cheapo 12V bilge pump (sparkfun sell one) which is putpose designed for shifting water. Mount it on the hull of the canoe with some rubber suckers and off you go.

    Or there’s always the 70,000BC invention called the “oar”.

  10. Don says:

    LOL sharpen the blades on the prop. Could be of use on zombies.

  11. gnomad says:

    clever hack, but the obnoxious noise removes every last ounce of the beauty of a canoe.

  12. PocketBrain says:

    must… adapt… to… my… bicycle…

  13. PI says:

    Neat build and a neat idea that inspires other ideas. In fact, given that Hackaday has posted hacks based on themes before, I think a series of rechargeable drill motor hacks would be awesome. But…

    If I see one more wanker arbitrarily attach the word “green” to a project, I think blood is going to start spraying out of my eyes and ears.

    What is green about a cheap electric drill (manufactured in a 3rd world country with no regard for worker safety, proper disposal of chemicals, or factory emission controls), a tiny rechargeable battery pack (that is not only inefficient, but full of toxic chemicals,) and a plank of pressure-treated wood (saturated in more toxic chemicals.) Let’s not forget all of the oil-sourced plastic implicit here… And then what…? After after an hour or two of accumulated use the intermittent-duty motor and gear train self-destruct and the whole enchilada ends up in the trash. Seriously… this is “green”?

    Back in the 50’s, marketing types decided that “atomic” was a word that people associated with high power and futuristic design. For a while, everything from toys to laundry detergent to chewing gum had the word “atomic” associated with its promotion or advertising. This imagery was directed at easily manipulated people with disposable income.

    Nowadays, the sucker word is “green.” “Green” is a word that allows certain people to absolve themselves of their guilt over being alive. “Green” projects, products, and policies enable these people to sleep soundly at night, deluding themselves into thinking that they’ve “saved the earth,” while what they’re actually doing is dumber and more eco-destructive than what they were doing before.

    Again, I have no issue with this project. I like it, and I want to see more like it. It’s just the arbitrary and superfluous use of the cursed G-word that raises my hackles.

    • S734L7H says:

      Well put PI. I totally agree about the G-word.

      Interesting project, but seems like an inefficient and noisy way to power a boat.

    • TacoStand says:

      No kidding. You want a “green” way to power a boat? How about a sail, or some oars? Either way you have something that can be made out of goods available anywhere (cloth, wood) and will never run out of power.

  14. NishaKitty says:

    Seems the prop could be made larger to make the boat move faster? It seems a little slow, though I am no boat expert ;p

  15. PJ Allen says:

    “Trolling motor”.
    It’s Trawling.


  16. N0LKK says:

    Wow! I must have missed the mention of “green” in the video, or on Barthos’ web page. Grinding flat for the chucks to grab on might help them not to loos their grip in prolong operation. Assuming a reversible drill, and a right angle adapter designed to be used with reversible drills the chucks are are appropriate for such use. Engine Vs. motor the only time I enter that debate, is when I realize doing so can really wind someone up that is really fervent about it.

  17. SparkyGSX says:

    I’d agree that drill motors and gearsets aren’t meant for continuous use, but any reasonably decent drill will have a lubricated all-metal gearset, that is designed to take some impacts when a drill ceases, and the full motor torque when the drill bit is stuck, both of which don’t happen in this application, so it will probably hold up for quite a while, if you keep it properly lubricated.

    The motor will get hot, but that could be fixed with a few extra vent holes and a fan for a little additional airflow. If the current is regulated, it will take some extra voltage for higher speed without wearing out to quickly.

    The bearings in the motor, which usually are slide bearings instead of ball bearings, and the brushes are probably the parts that will wear out first.

    Drills are cheap to come by second-hand, because the battery is usually the first part to fail. The stock batteries are far to small for this purpose anyway, and there is no requirement to use a compact, original battery when using the drill in this way.

    Just make sure the whole thing stays dry and clean, as water and dirt will destroy it very quickly.

    I guess the point isn’t to design the best, most efficient, and reliable drivetrain you can, but to use the parts you have available to build something reasonable.

  18. stib says:

    @karl You do realise that Top Gear is a British show, of which they made a fairly flaccid American (and a truly woeful Australian) version. Saying “the British Version of Top Gear” is like saying “the American Version of Coca Cola”.

  19. Berto says:

    Ok, maybe on the end of this line of ‘overwhelming’ and ‘serious’ comments, a ‘late’ comment of the maker of the project.

    SparkyGSX – Drills are cheap to come by second-hand, because the battery is usually the first part to fail. The stock batteries are far to small for this purpose anyway, and there is no requirement to use a compact, original battery when using the drill in this way.

    What to do with all this 1.000.000 cordless drills with NiCad. battery’s laying around for years in the makers shed?
    Take the cells out of the battery box and bring it to the intake station. Make in the battery box a socked for plugging an external 12V gel/lead battery. That’s what I did; recycling and re-use of a mostly unused cordless drill because of the battery.
    Recycling is ‘eco’ as is re-using! The wood I chooses was impregnated with wax without any ‘toxic chemicals’. The wood is sustainable, because they plant a new tree for the one they cut. You can call this a ‘eco method’. @PI – I just change the name to ECO and you feel already better, is’t it? When you don’t have a

    A cheap electric drill (manufactured in a 3rd world country with no regard for worker safety, proper disposal of chemicals, or factory emission controls), a tiny rechargeable battery pack (that is not only inefficient, but full of toxic chemicals,) then you are a non-hypocrite. The point is; Can I repair, re-use, recycle the existing stuff ? Many comments about the lifespan of the drill. Don’t worry, let it be a one- or two year use before ‘destruction'; we have a lot of fun with the canoe and the re-used cordless drill on the waters. It’s a fun project.

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