Definition
On a seaplane or flying boat hull, an abrupt break or notch in the bottom of the float or hull that allows the aircraft to rise up and plane across the water surface during takeoff, reducing water drag enough to permit acceleration to flying speed.
Plain English
A built-in step or ridge across the bottom of a seaplane's float that lets the aircraft skim on top of the water instead of plowing through it, so it can speed up and lift off.
Context Anchor
Used in seaplane operations, especially during water taxi, takeoff, and discussions of getting the aircraft “on the step.”
Derivation
From the everyday word 'step,' meaning a raised edge or change in level. The shape of the hull bottom literally has a step in it — the surface drops away abruptly behind the step, just like a stair tread.
Why Pilots Care
Understanding the step is essential for managing takeoff runs, avoiding porpoising, and achieving efficient liftoff from water.
Analogy
It is similar to the shaped bottom of a fast boat. At low speed the hull pushes through the water, but at higher speed it rises and skims more easily.
Intuition Check
Do not read “step” here as something a person steps on. In seaplane use, it means a shaped break in the bottom of the float or hull that helps the aircraft move over the water.
Example Sentence 1
As airspeed built during the takeoff run, the floatplane climbed up onto the step and quickly accelerated toward liftoff speed.
Example Sentence 2
A well-designed step allows the floats to break free of the surface cleanly during liftoff.