New Catamaran Loses Weight to Gain Speed

Derecktor Shipyards is putting the finishing touches on a 134.5 ft. high-speed catamaran for the Woods Hole Steamship Authority at the yard's facility in Mamaroneck, N.Y. Delivery is slated for May of 2000. The other bidders for the contract included Dakota Creek Shipyards, Halter Marine and Pequot River Works.

The Woods Hole, Martha's Vineyard & Nantucket Steamship Authority, the oldest of its kind in the U.S., provides the only year-round passenger and vehicle ferry service to the islands of Martha's Vineyard and Nantucket. Service is provided from Woods Hole to Vineyard Haven, and Hyannis to Nantucket. Seasonal service is also provided from Woods Hole to Oak Bluffs on Martha's Vineyard. Derecktor Shipyards tackled the contract in association with leading high-speed ferry designers, Nigel Gee and Associates (NGA) Ltd of Southampton, England.

"Following the tremendous success of the NGA designed 147.6 ft., 57 knots catamaran ferry for Buquebus, we feel very comfortable working with NGA" says Derecktor Shipyard's General Manager, Gavin Higgins, "The previous vessels we have built to NGA designs, have always surpassed the contract performance requirements. We are excited about winning this contract and look forward to working with Woods Hole to bring a new generation of vessel to their fleet."

The 134.5 ft. catamaran, is a larger version of the NGA 124.7 ft. passenger catamarans, which were built by Derecktor for New York Fast Ferry (NYFF).

"The 124 ft. ferry for NYFF was a commuter ferry," Higgins points out. "This new vessel was solely developed for tourist transportation. The vessel features 12 luggage carts, measuring four by three by five, which have pneumatic wheels, and are stored in a specific area in the bow.

"Basically, every tourist has at least a suitcase, and eliminating luggage congestion as one of the primary goals during the construction of this vessel. Additionally, the vessel features a large bicycle locker. Bicycles can simply destroy the interior of a boat, so with the setup on the new catamaran, they're kept stored away, and unable to damage the interior."

The vessel will be powered by Paxman 12VP185 diesel engines driving Kamewa 71SII water-jets to provide a speed of 36 knots with a full load of 300 passengers. Passenger accommodation is with aircraft quality seats on two decks with 171 passengers seated in a 3-3-3-3 arrangement on the main deck and 129 seated in a 4-4-4 configuration on the upper deck. Exterior seating is also provided on the upper deck to allow passengers the option of open-air travel.

"The vessel was designed for passenger comfort," says Higgins. "The upper deck is a bit more luxurious, and that's intentional, since it's a nice way to attract people up the stairs, and eliminate traffic on the main deck.

"This is a four-season boat, as well. There's ample heat [approximately 250 kW] and air conditioning [approximately 50 tons] on board. The system allows for 50 percent makeup air. Additionally, every one of the windows has its own demisting vent on it, so there's no 'fogging up' of the windows."

In addition to hull modifications to improve sea keeping, the vessel will be fitted with an active T-foil and trim tab ride control system from Maritime Dynamics to provide a high level of passenger comfort.

A particularly critical issue for the Woods Hole Steam Ship Authority was the wake wash generated by the vessel when operating in the wash sensitive areas at either end of the route. The proven low wash characteristics of the NGA 124.7 ft. vessel therefore played a major role in the selection of the vessel.

In independent tests carried out by Washington State Ferries, the NYFF ferry design was shown to have the lowest wake wash of any fast catamaran operating in North America that had been tested.

"Derecktor Shipyards has established itself as a leading manufacturer of high speed ferries in North America" says NGA's Technical Director, John Bonafoux. "Significant factors in the success of the vessels they have built are the very high standard of aluminum fabrication and machinery installations and their weight-conscious approach to vessel construction."

For speed of production, the hull and structure will be fully developed by NGA in 3D to allow nested piece part cutting code to be delivered electronically to Derecktor for CNC profiling of all aluminum plates.

"A lot of our focus was on keeping the weight down," says Higgins. "We used extensive amount of extrusion for that reason. Weight is speed on these boats, and this had to be a fast boat. We went into the project with a target weight, which we achieved.

"We also used composite intakes on this vessel, which we had used on our three previous commercial vessels. Basically, the benefits of composite over aluminum are, you never get any galvanic corrosion between the stainless steel and aluminum on the intakes; there's no cracking from vibration; and you can get smoother; fairer intakes out of composites.

"We think - for the commercial customer who wants to minimize maintenance - it's an outstanding feature," Higgins says.

The operator anticipates running the vessel initially on a three-season schedule, approximately 16 hours each day. The vessel is capable of making the Hyannis-to-Nantucket trip in approximately 40 minutes, so the operator is expecting to depart from each location once every two hours (allowing time for discharge and loading). Still, the 40 minute trip is a vast improvement over the two-and-a-half hour trip the displacement ferry currently offers.