The Naval Architect March 2008

Feature 2 | DIESEL AND GAS TECHNOLOGY
resulting in lower loading and higher estimated length overall of 186.6m and
open water effi ciency. gross tonnage of 28,500gt, giving a total
The arrangement is also reckoned speed of around 24knots. When compared
to create a more beneficial wake field to a reference vessel with conventional twin
behind a skeg and a clean wake field shaft line machinery, the W46-powered
for the thrusters. Wärtsilä estimates CRP version required an estimated 11%
that the concept off ers clear advantages less propulsion power demand.
over conventional twin shaft lines due Additionally, Wärtsilä has designed an
to lower fuel consumption, improved off shore support vessel with retractable
manoeuvring, and a payback time of less wing thrusters, claimed to combine the
than 10 years calculated for a 21,000gt Comparison between old rudder design low resistance of a single skeg hullform
short route ferry. and Wärtsilä’s efﬁ ciency rudder. with the manoeuvring performance
Podded controllable reversible pitch of steerable thrusters. This offers the
(CRP) propulsion is a further concept that possibility of gaining a high dynamic
has undergone development by Wärtsilä. positioning class.
It is said to offer lower power demand The concept could offer advantages
than twin shaft lines normally used in for a ship operator such as the same
ferries, as the aft propeller recovers some power plant benefits as a diesel-electric
of the rotative energy in the slipstream of machinery configuration, but with
the forward propeller and there is a more reduced emission levels and operating
favourable wake and lower resistance with costs due to lower fuel consumption.
a single skeg hullform. An alternative set-up utilising only
The company has produced a ferry one retractable thruster could lower
concept design based upon CRP thruster Machinery arrangement example of a investment costs, along with a smaller
propulsion, utilising a W46 engine, at an ferry powered by wing thrusters. space demand inside the vessel. NA
The Royal Institution of Naval Architects published the
18th edition of its annual Significant Ships series in
February 2008. Produced in our usual technically-
orientated style, Significant Ships of 2007 presents
approximately 50 of the most innovative and
important commercial designs delivered during the
year by shipyards worldwide. Emphasis is placed on
newbuildings over 100m in length, although some
significant smaller cargo ships, fast ferries and offshore
vessels have been considered, including a
cross-section of ship types, with each vessel being
either representative of its type or singularly significant.
Each ship presentation comprises of a concise
technical description, extensive tabular principal
particulars including major equipment suppliers,
detailed general arrangement plans and a colour ship
photograph.
available in printed or cd-rom format
SIGNIFICANT
Newbuildings include:
Tembek, Fram, Orange Trident,
Star, Deo Volente, Yacht Express,
SHIPS
Natchan Rera, Histria Giada,
Dubai Star, Hoegh Delhi,
British Emerald, plus many more
OF 2007
Non-member £46 (RINA member £40) When ordering please advise if printed or CD ROM format is required,
Or Order a set: contact: The Marketing Department,
One copy of Significant Ships 2007 RINA, 10 Upper Belgrave Street, London, SW1X 8BQ, UK.
& one copy of Significant Small Ships 2007 Tel:+44 (0)20 7235 4622 Fax +44 (0)20 7259 5912
price £61 (RINA member £52) E-mail: publications@rina.org.uk Website: www.rina.org.uk
52 The Naval Architect March 2008
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