This document analyzes the seastead design in terms of storm management, drogue systems, and related propulsion and stabilization mechanisms.
The seastead is designed to handle storms using a combination of propulsors, stabilizers, and drogues. Below is an analysis of theReturn to vessel Trajectory Analysis
The seastead will use differential thrust from the six RIM drive thrusters to control its trajectory while sailing downwind. The three legs act as daggerboards, providing stability and drag. The speed achievable and the forces acting on the stabilizers at various speeds are as follows:
| Wind Speed (mph) | Speed of Seastead (knots) | Stabilizer Drag Force (lbs) | Stabilizer Thickness (inches) |
|---|---|---|---|
| 15 | >5 | >500 | >1.5 | >
| 20 | >10 | >1,200 | >2.0 | >
| 25 | >15 | >2,200 | >2.5 | >
| 30 | >20 | >3,400 | >3.0 | >
| 40 | >30 | >5,600 | >4.0 | >
| 50 | >40 | >8,200 | >5.0 | >
| 60 | >50 | >11,400 | >6.0 | >
Notes:
For wind speeds exceeding the capacity of thrusters and stabilizers, a drogue system will be deployed to control the seastead's trajectory and reduce drift. The drogue will be adjustable, allowing for fine-tuning of drag and direction.
An adjustable drogue, such as a heavy-duty parachute/basket drogue with a collapse line (purse-string), is well-suited for this application. It allows for on-the-fly adjustment of the drogue's diameter, enabling control of drag and off-wind drift.
| Wind Speed (mph) | Target Speed (knots) | Recommended Drogue Diameter (ft) | Adjustability Range (ft) |
|---|---|---|---|
| 20 | >10 | >10 | >5-10 | >
| 30 | >5 | >20 | >10-20 | >
| 40 | >2 | >30 | >15-30 | >
| 50 | >1 | >40 | >20-40 | >
| 60 | >0.5 | >50 | >25-50 | >
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Galerider-style perforated drogues are another option. These drogues feature a perforated design, which can reduce the overall drag compared to solid drogues while maintaining good control in high winds.
Advantages:
Considerations:
A trailing drogue with an adjustable bridle is another option for controlling off-wind drift. This system allows the seastead to point at an angle to the wind, reducing drift while maintaining forward movement.
Advantages:
Considerations:
For maintaining a speed of 5 knots in 30, 40, 50, and 60 mph winds, the adjustable drogue system recommended earlier is the best choice. It provides the flexibility needed to adjust drag and control off-wind drift while maintaining a reasonable speed under control.
Notes:
For extreme high winds, a kite system can be used to move the seastead upwind or downwind at higher speeds. The three legs and foil shape will provide stability and control, while the kite will assist with propulsion.
Advantages:
Considerations: