Bow/Stern Thruster Sizing
Calculate required thruster power based on vessel characteristics
Thruster Recommendations
Recommended Thrust
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Thruster Power
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Minimum Tunnel Diameter
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Wind Load (beam on)
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Windage Area (est.)
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Battery Bank (min)
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Wire Size (to motor)
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Fuse/Breaker Size
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Thruster Sizing Guide
| Boat Length | Thrust (lbs) | Power (HP/kW) | Tunnel |
|---|---|---|---|
| 25-32 ft | 80-120 | 2-3 HP | 6-7" |
| 32-40 ft | 120-180 | 3-5 HP | 7-8" |
| 40-50 ft | 180-250 | 5-8 HP | 8-10" |
| 50-60 ft | 250-350 | 8-12 HP | 10-12" |
| 60-80 ft | 350-500 | 12-20 HP | 12-14" |
About Thruster Sizing
Thrust Requirements: Minimum thrust should exceed the wind load on the bow in beam winds. Rule of thumb: 1-2 kg thrust per meter of LOA, or 3-4 lbs per foot for moderate windage boats.
Tunnel Diameter: Larger tunnels provide more efficient thrust and reduce noise. Minimum tunnel diameter = approximately 15% of beam, but limited by draft at bow.
Electrical Requirements: Electric thrusters draw very high current (100-300A). Batteries should be located close to the thruster with heavy gauge wiring to minimize voltage drop.
Duty Cycle: Most thrusters are rated for intermittent duty (typically 4-6 minutes on, 15-20 minutes off). Plan maneuvers to stay within duty cycle limits.