The 72.80-meter (238’ 10”) Predator will go down in the annals of yachting history as the first Feadship with an axe-bow. Built by Koninklijke De Vries Scheepsbouw in Aalsmeer (NL), this awesome motoryacht also broke several other records at the time of her launch in 2008. Despite being among the quietest Feadships ever built, Predator has the tallest engine room, the longest uninterrupted interior views, the largest draught and carries an unprecedented four-engine propulsion package.
The background to the construction of a Feadship with an axe-bow can be traced to 2003 when a designer from outside the yachting world asked Feadship to investigate the feasibility of designing and building a superyacht based on a semi-submerged concept. Detailed technical research by the De Vries yard and De Voogt Naval Architects established that the best way forward would be to base the hull design on the axe-bow designs from the late 1800s. Although models were analyzed in association with the MARIN research institute, the design package was not taken further at the time.
A challenge for Feadship
Fast forward to late 2004 and Feadship is in discussions with the future owner of Predator, who has commissioned a modern and aggressive design for a sleek, fast-looking yacht. His primary requirement is for speeds around the 25-knot mark but he does not want to use jets or gas turbines. This raised a clear challenge for Feadship: Such high speeds on a on a 70-metre-plus yacht will inevitably result in high propeller blade loads if a conventional diesel-propeller propulsion set-up is deployed, creating excessive levels of noise and vibration.
In order to ‘minimize’ the required propulsion power, Feadship’s solution was a hull form with the lowest possible resistance. The owner was given a choice between a flared bulbous bow or an axebow. Seeing the hydrodynamic benefits of such an efficient displacement hull design and loving the raked look, he did not hesitate to go for the latter and the Predator project was confirmed.
Sleek and speedy
Meanwhile, Jaap van Keulen, chief designer at De Voogt (was responsible for all external styling, accommodation arrangements and naval architecture) went into top gear to ensure the axe-bow concept was completed in a yacht-like fashion. Avoiding the somewhat industrial look of inverted bows developed for commercial shipping, Predator’s profile flows elegantly aft to emphasize the speedy character of the yacht. And her dramatic looks have been further enhanced by the owner’s choice of red, white and blue exterior colors.
Predator’s skipper Greg Drewes, who has been at the helm of four Feadships and several other memorable superyachts during his 30-plus years at sea, is delighted with this performance. “The yacht handles better than any I have ever sailed. We have been in five-meter seas and Predator throws no bow wake. The V of the bow adds sufficient displacement as the bow enters a wave to give a very soft rise through the sea. There is no pounding and in smaller seas up to four meters she is as smooth as a flat sea. The lack of vertical movement makes Predator amazingly comfortable. There is no splash, no rise and no fall.” Predator’s ultra-slender angle of entry – combined with a bow that has considerably less resistance when rising – has resulted in an incredibly comfortable ride. And this is after all the essence of luxury yachting.
Captain Drewes is impressed with the comfort standards in other ways too: “The specs on noise, vibration, speed and handling also surpassed our highest expectations. We averaged 20 knots with two engines running at 1500 rpm, and at that speed Predator is as smooth as other yachts I have run at seven knots. When we kick in four engines at a top rpm of 1800, she does between 27 and 28.5 knots depending on the amount of fuel onboard and the sea conditions. Nonetheless, the power of the blades is such that Predator can slow to zero in little more than twice her length.”
Although casual observers may presume that it was the axe-bow design that gave the most headaches to the yard and naval architects, the greatest technological challenge was in fact the propulsion. Predator is fitted with four MTU 16V 595 TE90 diesel engines that give a combined power in excess of 23,000 bhp. They run in tandem with two Renk reduction gears, which were custom-built for this project and are the only two of their kind in the world. The gearboxes drive Rolls Royce controllable pitch propellers, which are an imposing 3.20 meters in diameter. This explains why Predator is the deepest Feadship yet at 3.70 meters.
Watching the weight
Another key element involved in attaining high speeds is a vessel’s weight. Predator has an aluminum superstructure and composite materials were used in the topsides. However, the relatively heavy steel hull meant that measures had to be taken to minimize the weight of the interior.
The interior was manufactured on a lightweight composite board system. Many of the wood panels and marble tops are in fact thin layers mounted onto honeycomb backgrounds. A radical weightsaving measure included the installation of a unique lightweight AC ducting system. This was based on aircraft industry technology and ensured that the integrated insulation weighs just one tenth of normal ducts.
– PR –