The ship design division of UK-based design, engineering and scientific services group BMT has unveiled a new hull design concept for autonomous (that is, uncrewed) vessels. This concept is called the Pentamaran platform.

The Pentamaran is intended for both defence and commercial applications. Defence applications for which the design can be configured include anti-submarine warfare, patrol, intelligence surveillance and reconnaissance, and hydrographic survey (the last can also be a civilian mission).

The design features a narrow central hull and two further smaller hulls, like sponsons, on each side, for a total of five hulls. On each side, the two small hulls or sponsons are set one behind the other. The main deck and superstructure are mounted over all five hulls.

The aim of this layout is to minimise hull drag through the water as far as possible. Tests have established that the Pentamaran design significantly reduces drag in comparison to mono-hulls (conventional single hull designs), catamarans (twin hulls) and trimarans (triple hulls). 

When the Pentamaran is operating in smooth water, the forward small hulls or sponsons on each side are not submerged in the water, and therefore do not generate any drag. These forward sponsons serve to supply roll stability when waves develop. As a result, the Pentamaran has less hull volume permanently immersed in the sea than a trimaran would have, resulting in reduced resistance through the water.

“Our team have carried out extensive work on this,” highlights BMT Specialised Ship Design Business Sector lead Martin Bissuel. “The data gathered through extensive towing tank testing is very compelling. For applications where fuel economy matters, the Pentamaran hull form is more efficient than conventional full forms, which means that using the same engines and the same amount of fuel, it will go further than any other, making it an ideal candidate for autonomous applications.” 

“Looking at it from a distance it may resemble a trimaran but that’s where the similarities end,” he explains. “The arrangement and careful positioning of the four sponsons makes all the difference. The forward sponsons stay above the water, and only come into action when the vessel rolls, so not only the drag is reduced, but the sea keeping characteristics are improved. Compared to a trimaran hull form, lateral accelerations are lower, reducing g-loadings [stress] on the structure as well as the antennae [sic] and sensors on deck.”

The design also provides significant deck area. “The wide deck offers a large working area for multi-role capabilities,” he points out. “It can accommodate payloads or interface with other systems such as unmanned air vehicles.”

For a vessel operating autonomously for significant time periods, a reliable propulsion system is essential. To this end, BMT’s engineers have incorporated several independent power sources into the Pentamaran design, thereby increasing both reliability and survivability.