Unit 6: Buoyancy

The Three States of Buoyancy: Deepening the understanding of Positive (floats), Negative (sinks), and Neutral (hovers) buoyancy.

The Relationship between Density and Volume: How adding air-filled foam (increasing volume without much mass) changes the ROV's density relative to water.

Moment Arm and Stability: Understanding that the placement of floats (up high) and weights (down low) creates a "righting moment" that keeps the ROV upright.

The "Weight of the Tether": Recognizing that the umbilical cable adds "effective weight" and drag once the ROV moves away from the edge of the pool.

Initial Float Attachment: Secure pool noodle segments or foam floats to the top rails of the PVC frame.
The Incremental "Trim" Test: Submerge the ROV in a test tank and observe its behavior. Students will "trim" (cut) small slices of foam or add small weights (washers/lead shot) until the ROV slowly sinks or hovers.
Center of Buoyancy Alignment: Adjust the fore/aft position of the foam to ensure the ROV sits perfectly level in the water, rather than "nosing down" or "tailing."Pressure Compensation Check: Observe if the foam compresses at depth, changing the ROV's buoyancy.

Success Criteria:

1. Static Neutrality: The ROV must stay suspended in the water column (neither hitting the floor nor breaking the surface) for at least 10 seconds with the motors off.

2. Self-Righting Test: If the student manually flips the ROV upside down underwater, it must automatically rotate itself back to the upright position.