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Propulsion Technology Waterjets for a Difficult Design Task The idea of a ferry going over the sea to Skye (see ferry route on map, upper portion of next page) is not a new one, though a challenge in terms of efficiency and comfort to say the least. Upon inves- tigation, it was found that a waterjet propulsion solution was the only viable option. The idea of a ferry going over the sea to Skye is not a new one, although with the Skye bridge opening a few years ago. it is not an adventure many people undertake these days. A small car ferry operates in the south of the island, and a large car ferry takes people over from Uig in the north west corner of Skye to the Outer Hebridian islands of Lewis and Barra. There had however, long been talk of a possible passenger service linking the North of Skye to the Scottish mainland at Gairloch. A feasibility study was carried out by the local council, after which some local businessmen pulled together to form a new company in 2003 called West Highland Seaways Ltd.. trading as 6° West. The requirement to make the route successful was that the journey must be Vessel Specification Length 48.4 ft. (14.8 m) Beam 13.1 ft. (4 m) Draft 2 ft. (0.6 m) Displacement 12.5 tons People (summer) 36 Passengers + 2 Crew Cargo (winter) 1 on or 12 Passengers + 2 Crew Speed 18 Knots Cruising Engines 2 x Cummins 6BTA5.9M Certification .. .EU Class C & MCA Workboat CoP done four times per day, in an hour and a half, requiring an average speed of 18 knots. The journey must be comfortable, but in a craft that could handle the rough sea conditions. While existing designs were offered with modifications to meet the new EU regulations on the safety of Passenger Vessels, they tended to be rel- atively heavy displacement vessels, which required excessive power and fuel consumption to achieve the 18 knots required. Ace Marine were approached, and responded with a new concept in boat design that was designed to be low cost, lightweight and comfortable, with reconditioned airline seats. The designer molded a relatively narrow hard chine planing hull form around six rows of seats with the intention of delivering excellent sea keeping qualities, both at speed, and at loitering speeds. The client specified a pair of Cummins engines for redundancy. The 26-in. diameter propellers required to push the vessel at 18-20 knots meant long shafts with brackets, and exposed rudders. In order to protect the propellers and rud- ders for beaching purposes, the designer • NON-HAZARDOUS • BIODEGRADABLE • NON-CORROSIVE • SAFE III l\ After RYDLYME Marine removed severe marine growth and freed up this bow thruster in a matter of hours! RYDLYME Marine is a safe, biodegradable marine descaler developed to dissolve problematic fouling mediums including calcium, rust, mussels, barnacles, and many other scale- formed mineral deposits that hinder the performance of vital water systems. ^RYDLYME fegradable Marine DeS a\e< 800-451-6291 Apex Engineering Products Corporation 630-820-8888 • Fax: 630-820-8886 www.rydlymemarine.com • dpetrille@rydlyme.com SAFE • BIODEGRADABLE • NON-CORROSIVE • NON-HAZARDOUS • Circle 208 on Reader Service Card Corrosion Control SALT REMOVING TREATMENT 100% Hon-HazardofiV'is^ 100% Non-Toxic 100% Biodegradable Nk . w S * . 85 w*!? ; - Reduce part and repair labor costs and down-time for everything where salt causes maintenance and operational problems. The favorite salt corrosion control maintenance product of thousands of users. 30 Concentrate available in case packs and drums. Salt-Away Products, Inc. • P.O.Box 8797 • Newport Beach, CA 92658 (714)754-7700 • Toll Free: 888-SALT-AWAY(725-8292) e-mail: sales@saltawayproducts.com • www.saltawayproducts.com Circle 253 on Reader Service Card Maritime Reporter & Engineering News
