Electric Outboard Motor

Ultra-light electric outboard motor for small watercraft (dinghies, kayaks, tiny fishing boats, etc).

Features

• Hubless rim-driven thruster (harder to tangle or damage — can go where it's shallow, safe for marine wildlife);

• No need to flush with fresh water after use in salt water (absolutely zero corrosion);

• Unsinkable (floats if dropped in the water);

• Waterproof (can be fully submerged, not afraid of the rain);

• Modular construction (easy to modify and repair);

• Very quiet and efficient (nearly no cavitation);

• Parametric design files (build a custom outboard motor to perfectly fit your vessel);

⚠ Caution!

Do not run dry — otherwise you're risking overheating, scratching, and possibly deforming the thruster.

Avoid hitting the ground — silt and sand can clog and seize the thruster.

Powerhead

TBA, currently the outboard uses powerhead from ThrustMe Kicker electric outboard motor

The final design implies use of 18–22V power tool batteries (e.g. Ryobi, Makita, Milwaukee, DeWalt, Ceenr, Hilti, Festool, etc) inside of a waterproof battery casing.

Parts

• 1 x IP67 Waterproof potentiometer

• 1 x IP67 3-position switch

• 1–4 x Waterproof 18V power tool battery compartment(s) [e.g. from Ryobi Power Cleaner]

• 1 x ½" round neodymium magnet (for kill switch lanyard)

• 1 x Magnetic reed switch

• 1 x 360º light (optional)

• 1 x horn (optional)

• 1 x spirit level (optional)

Transom bracket

TBA, currently the outboard uses transom bracket from ThrustMe Kicker electric outboard motor

Parts

• 2 x titanium bolt

• 2 x titanium nut

• 2 x large titanium washer

Midsection

This part can either hold the ESC controller, or be left hollow and contain thruster cables (running all the way from the lower unit directly to powerhead).

You could also try to use the midsection from ThrustMe Kicker, but the original controller there needs to be “tricked” into working with DiskDrive 80 — since its stator's diameter is many times larger than that of the stock Kicker's thruster.

Parts

• 1 x 18–24V 500W+ brushless motor controller [e.g. https://www.ebay.com/itm/395359847535]

• 2 x press-in threaded insert

• 2 x screw

• 3 x female bullet connectors

• 1 x power connector (1 male and one female bullet connector)

• 2 x thick o-ring

Printing

Depending on your 3D printer's volume, either print it as one part, or as two parts and then glue them together.  Go with 50% infill or higher (i.e. 3D honeycomb).  Use high-quality heat-resistant rigid filament (e.g. PETG-CF).  Minimum three wall loops.

Assembly

Put a good amount of strong fibers into the reinforcement tunnels, seal them with epoxy resin.  Insert the ESC (or wires), drill a hole at least 10cm from the bottom, inject some sort of silicone (or some other water-resistant sealant) through that hole, let it cure.  Reinforce the hollow tube with a couple of layers of carbon fiber.  Use soldering iron to install two metal press-in threaded inserts at the top.

If the ESC is being installed in the midsection, use heat-conductive resin or glue to embed it inside the tube, in order to protect it from water damage, as well as making the surrounding water cool the controller.  If it's just three wires and nothing else, it might be a good idea to pour some sort of foam to keep those wires from moving, as well as preventing water from filling the inner space in case of a leak.

As the last step, lubricate and put on two o-rings onto the tip.

Lower unit

Serves as hydrodynamic enclosure for the motor.  Needs to be kept light, smooth, and waterproof.

Parts

• Hydromea DiskDrive 80 thruster — https://www.hydromea.com/diskdrive-thrusters?pgid=m3ipsew1-

• 1 x press-in M3-0.5 threaded insert [e.g. https://www.alliedtitanium.com/products/fasteners/nuts/insertnuts/vupdc_Detail.php?UPDCID=149646003]

• 1 x M3-0.5 x 8mm (Torx) countersunk socket screw [e.g. https://gorillabrakes.com/products/m3-countersunk-titanium-bolts?variant=47900664987967]

• 3 x male bullet power connectors

• 4 x M5-0.8 or #10-32 titanium/composite (tapered) socket head 35mm screw [e.g. https://racetechtitanium.com/product/titanium-10-32-x-1-25-tapered-socket-head-cap-screw-shcs/]

• 4 x M5-0.8 or #10-32 titanium/composite (cap) nut [e.g. https://racetechtitanium.com/product/titanium-10-32-jam-nut/]

• 2 x thin o-ring (optional)

Printing

Print as two separate parts ("Body" and “Tail”).  Rigid filament for the body, optionally flexible filament for the tail (cap).  Go with 3+ wall loops, 3D honeycomb or similar infill pattern (at least 10%, but not too much — to keep it light and buoyant).  Going with clear (transparent) filament could add a nice effect and provide ease of inspection.

Assembly

1. Put metal rods or lots of fibers into reinforcement channels, fill them with epoxy resin.

2. Install one press-in threaded insert.

3. Sand and coat with at least one layer of UV-resistant epoxy (optional)

4. Attach two thin o-rings (optional) insert thruster, put on the tail section, fasten everything together using titanium, composite, or stainless steel hardware.

Manufacturing tips

• Round every tube's edges (including both sides of screw holes) to keep them smooth — otherwise o-rings will get scratched or sliced;

• Sand and coat all parts with a thin layer of epoxy — this way o-rings will provide better seals, and the chance of water penetration is reduced greatly;

• Use o-ring grease;

• Use Loctite to make sure fasteners don't get loose due to vibration;

• Use glue-laced heat shrinking tubing on all connectors (unless you decide to go with something like Deutsch connectors);

• Before laminating, mark the tube's end(s) with a thin layer of contrasting paint — this way you'll know where exactly to stop removing excessive fibers after the laminate is cured;