What is a step on a hull?
The step is a transverse stall in the hull. It is found on boats with a V-shaped planing hull, designed for speed. It comes from racing boats reaching very high speeds.
The step is a "step" that works when the boat is out of the water. It affects the water flow and reduces drag. The step creates a vacuum behind it, which has the effect of sucking in air, either from the edges of the hull or from a piping system coming from the deck. An air cushion is created, reducing friction, as air is less dense than water. It is thus possible to increase speed or limit fuel consumption at a speed equivalent to that of a conventional hull.
The ventilation under the hull makes the hull grip less in turns and requires some attention in maneuvers.
| Benefits | Disadvantages |
| Friction reduction Decrease in consumption Increase in speed | Less stability Careful maneuvering in turns |
The particular case of the AirStep by Bénéteau
Bénéteau has developed its own step, the AirStep, which can be found on some of its powerboats. In September 2015, it presented the second generation of AirStep technology. Significantly improving efficiency, this advance allows, for the same speed performance, to go up in unit size without having to increase their engine power.
Developed since 2003 and based on technologies used by the aeronautics industry, the AirStep aims to offer a new generation of hulls that provide more sensation in terms of speed and acceleration, while improving safety, comfort and performance of boats. Initially reserved for outboard engines, this patented technology can now also be used on Z-drive units up to 44 feet.
In 2014, it underwent its first evolution to further increase the performance of the hulls of the new Flyer outboard range. Today, the Air Step technology is compatible with the IPS inboard motorization.
The AirStep adds a forced ventilation system to the steps in the hull geometry. An air capture point at the console is connected to the front tip of the step, designed in a chevron shape. The air rushes in and out of the sides of the hull.
The AirStep 2 allows to multiply by three the volume of air under the hull and thus to improve the speed, that is to say + 1,5 knot of max. speed on the GT40 compared to the GT 38, and the storage capacities with + 700 kg for the same performances.
