Aquamarine Services Director, Scott Cumming, regularly writes for Club Marine Magazine. This latest article discusses steering systems.
This article explores the types of steering systems found in high-performance boats, with a focus on single-outboard-powered monohulls or modified vee-hull boats – think Labsport, Bullets, Haines SO, Force and similar.
These types of performance boats share some common characteristics. They’re relatively lightweight. They have a high horsepower-to-weight ratio. They rely to varying degrees on some amount of ‘lift’. That is, as speed increases, the hull lifts progressively out of the water, which reduces drag and therefore increases speed.
Because of this, the steering system becomes an important part of controlling the vessel, as opposed to just choosing the direction you wish to travel.
Boats of this style have a huge following and countless examples are being driven by enthusiasts on any given weekend. That said, a good degree of caution and the right experience when operating fast boats is paramount.
Underpinning mechanics
Fast monohull outboard-powered boats feature a hull specifically designed to allow the boat to achieve high speeds. Speeds at which the steering system becomes necessary to control the dynamics of the boat.
A commonly found feature is a ‘running plank’. This is a flat section at the bottom of the hull’s vee to increase hydrodynamic lift and to some extent improve handling.
In most cases, they’re powered by a single outboard with a propeller that’s usually right-hand rotation. This means the outboard will typically want to turn the vessel to the right, so part of the steering system’s job is to counteract the outboard’s force.
Up to a certain point, these boats gain a top-speed benefit from raising the engine height on the transom to reduce drag. This ‘surfaces’ the propeller, which means that some of the propeller blades are in the water and some out. As the propeller rotates, the forces involved will typically increase the force that causes the outboard to turn or pull to the right.
Continue reading this article.
