Underwater Quadcopter Tug Concept vs. Traditional Submersible Mixers
Simplified representation of seastead with angled columns and submerged floats
As you correctly noted, thrust generation follows Newton's third law:
Thrust (F) = mass flow rate × velocity imparted to water
Power Required (P) = ½ × mass flow rate × velocity²
Therefore: F/P ratio = 2/velocity
This explains why large, slow-moving propellers (2.5m diameter, low RPM) are efficient for static/bollard thrust applications like maneuvering a seastead.
The proposed system would function as an external tug, connected to the seastead via cable:
| Factor | Underwater Quadcopter Tug | Dual Submersible Mixers |
|---|---|---|
| Thrust Efficiency | Potentially similar with large props | Optimized for static thrust with 2.5m props |
| Maneuverability | Excellent (omnidirectional) | Good (differential thrust) |
| Installation | Simple cable attachment | Complex hull integration |
| Maintenance | Easier to retrieve and service | May require dry docking |
| Redundancy | Single system (lower) | Dual systems (higher) |
| Development Risk | Isolated from seastead | Tied to seastead structure |
| Operational Complexity | Higher (autonomous control needed) | Lower (simple motor control) |
| Cost | Potentially higher initially | Potentially lower (established tech) |
The underwater quadcopter tug concept presents intriguing advantages for your seastead application:
For your specific use case: The modularity and vibration isolation aspects are particularly compelling for a living structure where comfort matters. The ability to develop propulsion separately from the main structure could accelerate iteration and testing.
Recommended path forward:
Bottom line: The quadcopter tug is technically feasible and offers compelling advantages in modularity and vibration isolation. However, it introduces new complexities in tether management and control systems. For a pioneering seastead project where innovation is valued and system isolation is beneficial, this concept is worth serious investigation, beginning with a proof-of-concept prototype.