What affects boat speed?

We’re likely preaching to the converted here, but as far as we’re concerned, there is really nothing quite like cruising across open waters.

The thrill that comes from high-speed boating is the life and soul for many boat enthusiasts and, once you get a taste for it, it’s always tempting to work out ways to get the most out of your vessel.

In order to do that, you need to consider all the different factors that can affect boat speed such as the engine you’re using, as well as the size of the boat and weight which also play a large role.

Hull Shape Speed

The hull of any boat has a profound effect on its speed when traveling through the water. There are a number of different hull shapes that serve the function of the vessel. Powerboat’s hulls are typically categorised into three types; Displacement, Semi-displacement, and planing hulls.

A Displacement hull works by diverting water out of the way around the bow when moving through or sitting on the water. The planing hull, however, uses hydrodynamic lift to skim across the water’s surface. The reduced contact with the water allows powerboats to move at a much greater velocity over water.

In order for a powerboat to generate any lift at all is dependent on the speed the powerboat is traveling. Planing speed is the velocity the boat must travel in order to generate lift if the powerboat is traveling at less than the planing speed, the hull will act as a displacement hull, as it is generating no lift.

Boats with displacement hulls travel at a reduced, consistent velocity, while semi-displacement hulls are designed to combine the features of displacement and planing hulls, displacing water at low speeds, while maintaining the ability to generate lift at cruising speed. Semi-displacement hull boats are great all-round vessels, but if speed is your passion then planing hulls are the way to go.

How does weight affect a boat’s speed? 

As a boat moves through the water it displaces its own weight in the water. If a boat is heavy it is forced to push a greater volume of water out of the way, in turn creating more water resistance. When a boat reaches hull speed (the point at which the bow and stern waves meet) a one wave system is created, heavy boats can become trapped in this system, which restricts the velocity they can travel at as they are constantly fighting the waves head-on.

Engine size 

The size and power of your engine play a huge role in dictating the speed at which you travel.

Boats with semi-displacement and planing hulls may opt for larger more powerful engines like our CXO300 Diesel outboard engine. While racing yachts may opt for slightly smaller engines with less horsepower, as they rely on the sails in order to reach their top speed.

If you want to know more about boat speeds or looking for more information on the CXO300, please contact your local Cox distributor. Stay up to date with how the Cox team is feeling in the lead up to production.