MAN Diesel & Turbo’s Propeller & Aft Ship organisation has announced an order to retrofit and upgrade 11 vessels in the Odfjell chemical tanker fleet.
The vessels are of the Kværner class (about 37,500 dwt with 52 cargo tanks) and are due for docking from 2015 to 2017, during which time the upgrades will be performed including a new propeller with Kappel blades, fairing cone and a rudder bulb.
All are customised for each tanker’s hull and rudder designs. The calculated power saving has been verified by tank-test analyses conducted at MARINTEK (Norwegian Marine Technology Research Institute) which has reported the preliminary results.
The first vessel of the sister ships, Bow Clipper (1995), will dock and be upgraded in August 2015. The vessels currently have MAN B&W two-stroke engines powering a four-bladed, controllable-pitch propeller and a PTO-driven shaft alternator.
The vessels’ new service speed at reduced main-engine output – combined with the more-efficient Kappel propeller blades, a fairing cone and a pre-fabricated rudder bulb kit – should contribute to power savings and reduced exhaust-gas emissions.
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“It’s a very exciting project and we are proud to be part of it. With our new design possibilities, we are furthermore looking forward to offering this fuel-saving concept to other fleets with similar operational patterns,” said Kjartan Ross, business development manager of MAN Diesel & Turbo’s Propeller & Aft Ship organisation.
He continued, “With the long lifetime expectancy of Odfjell’s high value, quality vessels, this upgrade investment is straightforward and very attractive.”
The Kværner-class vessels currently scheduled for upgrades are Bow Cardinal, Bow Cecil, Bow Cedar, Bow Chain , Bow Clipper, Bow Fagus, Bow Faith, Bow Firda, Bow Flora, Bow Flower and Bow Fortune.
Kappel propeller blades have an extended tip, which is smoothly curved to the suction side of the blade to reduce energy loss from tip vortex flow. The fairing of a propeller hubcap and a rudder bulb reduces energy loss from hub vortex and drag from hub and rudder.