For a planing hull, what determines the top speed?

For a planing hull, what determines the top speed?

• A. Waterline length
• B. Hull color
• C. Amount of power available
• D. Ambient air temperature

Answer: (C)

Top speed for a planing hull is determined by how much propulsion power you have and how effectively that power is turned into forward thrust to overcome water resistance. When the hull planes, the drag is reduced because less hull is in the water, but drag still rises with speed, so boosting power generally allows you to reach higher speeds until other limits (engine/drive capability, propulsion efficiency, hull design) cap further increases. The waterline length mainly limits displacement-hull speeds, not the maximum planing speed; hull color and ambient air temperature don’t determine how fast you can go under normal conditions.

Top speed for a planing hull is determined by how much propulsion power you have and how effectively that power is turned into forward thrust to overcome water resistance. When the hull planes, the drag is reduced because less hull is in the water, but drag still rises with speed, so boosting power generally allows you to reach higher speeds until other limits (engine/drive capability, propulsion efficiency, hull design) cap further increases. The waterline length mainly limits displacement-hull speeds, not the maximum planing speed; hull color and ambient air temperature don’t determine how fast you can go under normal conditions.