Based on the Axe Bow concept developed by Damen Shipyard in Holland for larger ships, the concept has been modified to create an advanced all weather hull design for smaller boats with a superior seagoing ability.
Damen Shipyard is working with the Dutch lifeboat organisation, the KNRM, and design team De Vries Lentsch Design to develop this new concept in lifeboat design. This new design is based on a RIB, like all the modern Dutch lifeboats, but it features a wave piercing bow. This hull concept is claimed to give the hull a better performance in head seas without losing other aspects of performance.
Tank tests have taken place at Marin in Wageningen to evaluate the performance of the proposed hull design in waves. The Axe Bow was developed at Marin and this new lifeboat design is an attempt to translate the concept into smaller sizes. In larger sizes Axe Bow ships are used in the offshore oil arena and as super yacht support vessels.
It is proposed that the new lifeboat design will have a length of 19m matched to a draft of just 1.10m because the Dutch lifeboats are often called upon to operate in shallow water. Water jet drive will aid this minimum draft and the jets will be coupled to a pair of 1,000 hp diesels to produce speeds of up to 35 knots, making this new design one of the fastest all weather lifeboats in existence.
The Axe Bow lifeboat has a high vertical stem that cuts through the waves with minimum lift so there is less chance of the hull contouring over the wave. In the tank tests the hull produced a much more level ride with reduced pitching motions. Apart from the modified bow shape, the lifeboat hull is a conventional deep vee shape with a deadrise of around 20° to provide a well cushioned ride in waves and good planing performance.
The lifeboat has a fully enclosed wheelhouse that makes the design self-righting. The KNRM use inflatable tubes that feature a double skin with a foam layer between the two skins. On this new lifeboat design the tube has a small diameter at the bow, it increases in diameter out as it runs aft and it will have the same type of heavy duty construction.
The KNRM will be inviting tenders for the construction of a prototype of this new design for extensive testing at sea and it seems likely that Damen will be a preferred bidder for this contract. The hull will be constructed in aluminium like all the Dutch lifeboats and there is the prospect of this hull concept being marketed by Damen for other commercial uses such as pilot and patrol boats.
If this new lifeboat design proves superior to existing lifeboat designs in extended trials then it is likely to be adopted by other lifeboat societies.
Further information: www.damen.nl
By Dag Pike
