In January, Finnish shipowner Meriaura Group signed an order for two 4,700 ton deadweight Ice Class 1A VG EcoCoasterTM general cargo ships at Dutch yard Royal Bodewes.
Foreship Ltd, the naval architecture firm that designed the vessels, says their hull form and machinery optimization is expected to result in almost a 50 percent reduction in fuel consumption as compared to conventional dry cargo vessels of similar type and size.
That is of course, a substantial claim to make, but what this really means to a prospective ship owner, or to Meriaura Group in this case, is that Foreship crunched a bunch of numbers and analyzed 45 different hull alternatives of varying lengths and hydrostatic characteristics using Computational Fluid Dynamics to come up with this design that is particularly optimized to work as a coast-wise cargo ship.
Risto Ajanko, Senior Specialist, Hydrodynamics at Foreship says their aim was to “minimize resistance while achieving small wave formation and good wake field for the propeller. The main dimensions of the EcoCoasterTM were optimized, achieving the best ratio between capacity and fuel consumption.”
Foreship’s design features include a long and narrow bow that they say will achieve lower resistance in ice channels, while flare angles minimize additional resistance in waves. The aft shape features a narrow gondola to enhance wake field for the propeller.
Foreship says its aft hull design is little bit different from what can typically be seen in designs for this kind of vessel as the low hull resistance and high propulsion efficiency were considered as a design parameter from the start. High propulsion efficiency is achieved using a large propeller with low RPM together with a propulsion improvement device (rudder bulb), while also keeping in mind optimized wake field for the propeller.
The vessel will be powered by an Anglo Belgian Corporation 8DZC medium speed main engine which will be suitable for biofuel and MGO. VG-Shipping (part of Meriaura) operates its own biofuel refinery in Uusikaupunki.
The owner’s goal is for EcoCoasters to make up at least half of its fleet (currently 20 vessels) within five years. Foreship says a larger EcoCoaster design is also under development