After a quarter of a century the Sea Axe remains unbowed

Recently, the Delft University of Technology (TU Delft) held an event to commemorate the life and career of renowned researcher Lex Keuning – 1950-2023. During the event, a plaque was unveiled in the towing tank where, for almost 40 years, he carried out valuable work that improved conditions for those onboard ships.

Damen Research, Development and Innovation (RD&I) Programme Manager Albert Rijkens, speaking of this event, says, “The plaque and the gathering are a recognition of Lex Keuning’s professional life. Today, we are still reaping the benefits of his work.”

For Damen, perhaps the clearest example of this continued influence is the iconic Axe Bow – a distinguishing feature of many of its vessels.

The story begins

The story behind the bow begins one day back in1980 . Lex Keuning is onboard a high-speed Damen vessel conducting tests when, all of a sudden, the ship came down – hard – on the waves.

Almost everybody onboard is injured – including Lex who sustains two broken knees. It was to be a turning point; from this day forward, Lex will dedicate his career to improving seakeeping behaviour of fast-moving vessels with a view to improving life onboard.

Momentum grows

His research soon led to the development of the Enlarged Ship Concept in the 1990s. With this, the forward section of the vessel is extended, thereby reducing motions. It’s a feature that quickly finds its way into the Damen portfolio, being successfully applied to the Stan Patrol 4207 and Stan Patrol 4708 vessels.

The Enlarged Ship Concept was, however, only the foundation for further developments. By 2001, Lex evolved the concept into the Axe Bow. This concept was later further researched in a project collaboration between TU Delft, MARIN (Marine Research Institute Netherlands), the Royal Netherlands Navy (RNLN), US Coast Guardand Damen (High Speed Craft & Damen Schelde Naval Shipbuilding).

Researcher Lex Keuning (1950-2023)

Cutting clean

This distinctive, vertical, axe-shaped bow slices cleanly through the waves, minimising slamming and allowing more gradual re-entry into the water, as Albert explains.

“The bow has the greatest draught at the front, which delays the moment at which the bow lifts out of the water. If the bow does not lift, there is no chance of it slamming back into the waves.”

Additionally, the improved seakeeping performance of the vessel results in a significant increase in efficiency, lowering both fuel consumption and emissions.

Distinctly Damen

Damen quickly began to incorporate the design in its vessels – first on monohulls and later on catamarans, the so-called Twin Axe. Today, it is a widely recognised feature of many Damen vessels, including the successful Fast Crew Supplier (FCS) series.

Keen to secure the continuous innovation of design features that would make being onboard a ship more comfortable, Lex then established the Axe Bow Fund, an innovation to which he proposed placing revenues generated by the Axe Bow patent. This contribution was then doubled by Damen.

Fund for the future

The fund is used to support shipbuilding research projects, the proposals for which are jointly evaluated by TU Delft and Damen.

Examples include the development of the FCS 7011 Aqua Helix. The vessel is capable of sailing continually at speeds of up to 40 knots, enabling short transit times.

Alongside speed, comfort for the crew and up to 200 passengers was also a high priority. The FCS 7011 is able to conduct safe, comfortable transfers in conditions of up to 3 metre significant wave height.

Across the portfolio

During the development of the Aqua Helix, explains Product Portfolio Manager FCS Vincent de Leeuw, Damen gained insights that are now benefitting other vessels.

“For example, we are now often using large, bonded windows, as opposed to bolted ones. This is just one example of how lessons learned in one project find their way across the portfolio.

“We miss Lex’s intellect and creativity,” he continues, “but his legacy is visible in every FCS Damen builds.”

Next steps

Another, ongoing, research project to benefit from the fund is one focused on wind-assisted ship propulsion (WASP). Albert, who leads the project, says, “We are working with twelve researchers to make the shipping industry more sustainable. It is one of the ways in which Lex Keuning’s legacy continues. And, thanks to the fund, we can continue working on the next steps.”