Hysucat technology: Gliding is fun, but floating is electrifying.
It is easy to make boats fly over the surface of the water, but in practice this is a difficult task that has challenged designers for over a century. Since the 1980s, however, tremendous progress has been made in this direction, not just for fun or sport, but to provide some functional benefits in daily life and improved efficiency. The new foiling technology, originally invented for military purposes in the 1980s, found its way into service and tender boat construction for various purposes.
Since the development of RIB boats in the early 1970s, development has focused on improving performance and the materials used. Hard hull hits, instability and increasing fuel consumption were long considered invincible side effects. Until the early 1980s, when two men at Stellenbosch University in South Africa improved RIB technology with catamaran hulls and foils. It may sound simple, but in reality it required years of trial and error and testing, with dozens of pages of data analysis and engineering searches. Why so serious?
Foiling refers to the use of hydrofoils attached to the hull of fast boats to provide additional lift at planing speeds-often enough to lift the hull completely out of the water. Foils work much like airplane wings. Simply put, as they move through the water, they deflect the flow, which exerts a force on the foil. When this force is directed upward, the faster the boat goes, the greater the lift.
Foiling may seem like a recent technological phenomenon, but it has actually been developed for 100 years. The first development of a foiling watercraft was a 60 hp motorboat designed and built by Italian inventor Enrico Forlanini in 1906. He obtained patents in both the United Kingdom and the United States. Soon after, he had a prototype in operation on Lake Maggiore. British boat designer John Thornycroft followed with a series of 1:2 scale models with stepped hulls and a single foil, and by 1909 had a complete prototype of 22 feet in operation. Later, Alexander Graham Bell broke the world ocean speed record in 1919 with his Hydrodrome 4. During World War II, the German Army developed a 17-ton foiling minelayer that was tested in the Baltic Sea at speeds up to 47 knots.
In the early 1950s, the first commercial hydrofoil ferry service ran between Italy and Switzerland, and a decade later a private hydrofoil yacht was featured in the James Bond film "Thunderball." However, it took until the 1960s and 1970s for foiling technology to be introduced into military and commercial use with the launch of the Boeing Jetfoil, first in service in the Hawaiian Islands and later in Hong Kong and Macau. Traditionally, high-speed hydrofoils were used with large V-shaped foils that extended beyond the width of the boat. This made mooring difficult and increased draft. They were also expensive to build, prone to damage, and difficult to operate because the propellers of conventional propulsion systems were out of the water once the boat foiled. Although hydrofoils were often more efficient than conventional hulls, high-speed catamarans could usually achieve the efficiency without the disadvantages. The problem, however, was the decreasing stability of catamarans at high speeds.
These facts served as the starting point for further research for speed boat racer Malan Conradie and Professor Gunter Hoppe, a world-leading authority on hydrofoil technology and head of Marine Dynamics at Stellenbosch University in South Africa. The idea of developing a fast, stable and efficient foil-assisted catamaran hull with no side effects intrigued the duo, and the studies began. Conradie worked with Professor Hoppe for 15 years. Conradie did the engineering, interior and exterior design work, and Professor Hoppe designed the hydrofoils. All designs were tested in the test tank facility at the university, and sea trials were conducted to evaluate the hydrofoil concept. At a later stage, Conradie took the beta-version hull to offshore powerboat events, where it demonstrated its superior design by outperforming the competition.
This collaboration led to the birth of the original Hysucat - "Hydrofoil Supported Catamaran" - and resulted in a new breed of hull designs that became popular in South Africa and later worldwide.
So what is so special about Bering Marine? First, it's the hull, or more precisely, the hulls, which consist of an asymmetrical planing catamaran hull and a special hydrofoil system. The main hydrofoil, located between the catamaran hulls, works like a classic foil in a fluid medium. The top creates an area of low pressure, the bottom creates an area of high pressure, and the mass of passing water is deflected downward. The result is far more efficient lift than planing surfaces of the hull. Typically, the lift/drag ratio for a planing hull is 4:1, while that of a hydrofoil is 20:1. The main foil is a stainless steel chevron-shaped wing positioned slightly forward of the boat's center of gravity, spanning the tunnel between the catamaran hulls. It is mounted parallel to the bottom of the hulls, but does not protrude below them. As a result, the wing is always in the water and there may also be some protection in case of accidental grounding. Undoubtedly, the air trapped and compressed in the tunnel at higher speeds also contributes to the lift potential before it drains through the end of the tunnels at the stern.
Smaller trim hydrofoils are also located inside the catamaran tunnel near the stern. These smaller foils play an important role in the automatic longitudinal trim stabilization of the hull. When they reach the water surface inside the catamaran tunnel, the bow lowers, their buoyancy decreases (due to free-surface effects) and then, due to the reduction in buoyancy, the stern lowers again.
Generally, hydrofoils are protectively mounted between the catamaran hulls and attached as low as possible to the hull keels to keep them fully submerged but not protruding below the keel. Since they do not protrude below the hull and are no wider than the tunnel beam, there are no operational or aesthetic limitations to attaching hydrofoils.
The benefits of this unique hybrid system reinforce many of the existing advantages of the catamaran hull.
These include: Because of the catamaran-shaped hulls, Bering Marine boats have lower running resistance. As a result, high speeds can be achieved with low-power engines with up to 70% less fuel consumption. This offers dual benefits in terms of cost-effective engine setups and lower fuel costs.
