Unit 4: Waterproofing

The Properties of Hydrophobic Materials: Why wax and electrical tape are effective barriers against water molecules.
Thermal Management: Understanding that while the wax keeps water out, it also traps heat; why motors shouldn't be "dry-fired" for long periods.
Corrosion Prevention: The role of waterproofing in protecting the copper commutator and brushes of the DC motor from oxidation.

The Wax "Potting" Process: Melt toilet bowl wax (ring wax) and carefully inject or pack it into film canisters or thruster housings to encase the motors.

Axle Alignment: Ensure the motor shaft is perfectly centered and spinning freely while the wax cools/settles to prevent friction.

Tether Management: Apply electrical tape and zip ties to create "strain relief" so the weight of the cable doesn't pull the wires out of the waterproof seal.

• The "Bucket Immersion" Test: Students submerge their completed thrusters in a 5-gallon bucket of water for 5 minutes.

• The Success Metric: After 5 minutes, the motor must be powered on briefly. If it spins consistently without stuttering or "smoking," and no oily sheen appears on the water surface (indicating a wax leak), the thruster is certified "Sea-Ready."