• Staff Writer

The Planing Hull: Speed & Stability

Updated: Sep 28

Motorboat with a planing hull

What is a planing hull?

A planing hull is a boat hull designed to move through the water more efficiently at high speeds.

Manufacturers shape the hull to lift the bow and stern at speed and "plane" across the surface.

Wakeboarding, waterskiing, and racing boats use this design. On motorboats, these hulls have a V-shape.

This design reduces the amount of resistance and drag. The strakes — the strips you see running along the sides of the V-shaped hull — further reduce surface friction.

At a high enough speed, the hull pushes the water down and creates lift.

Displacement hull

In contrast, sailboats have displacement hulls that cut through the water rather than rising above it. As a result, the boat pushes water to the sides rather than downward.

A round-bottomed hull shape acts as a displacement hull. Sailboats with this hull sit at the same draft, whether at rest or under sail.

Displacement Hull

Large cruisers also have displacement hulls, allowing them to travel more smoothly through the water.

Boats with displacement hulls are limited to slower speeds.

From displacement to a plane

When motionless, all boats are in displacement mode.

Force equal to the weight of the fluid displaced by the watercraft is what buoys it. This effect is known as Archimedes' principle.

As more power is applied to a boat with a planing hull, the watercraft initially plows through the water and creates a large wake.

But, at high enough speed, the boat will start to plane — or skim — across the surface of the water.

When a boat is planing, it is highly maneuverable and stable.

On the minus side, planing hulls are unsuitable for vessels that operate in heavy waves or very shallow water.

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