Feature 2
Th is will result in a cheaper but heavier the ship to operate at slow speeds over Renk gearbox.
displacement vessel overall. Th is decision long periods, it is not intended to be used Th e combat system, or Sensor, Weapon,
refl ects the aim of acquiring a relatively while manoeuvring. Th is means that full and Command (SEWACO) system
cheap, robust platform with good power on main diesels must be available specified for the Patrol Ship design
seakeeping capabilities. while leaving port, coming alongside or refl ects the needs of low intensity taskings
Active fin stabilisers will be fitted anchoring, and also conditions the choice in predominantly littoral environments;
to improve seakeeping in higher sea of controllable pitch propellers. Confi ned while relatively lightly armed, the ship
states. Th is represents something of a manoeuvring is aided by a 400kW must be endowed with a very high degree
departure given the Royal Netherlands bow thruster. of situational awareness in order to track
Navy’s previous preference for rudder Selection of the main propulsion diesel and interdict small, fast and oft en fl eeting
roll stabilisation. engine sought to ensure that the margin contacts of interest. Th is has led to the
With the PS staff requirement having between the propeller curve and the development of a new sensor suite, hosted
set out a maximum sustainable speed of diesel curve was suffi cient so as to avoid in an integrated mast, that addresses the
20knots (six months out of dock in Sea regular overloading when manoeuvring, specifi c challenges of the littoral.
State 4), a range of 5000 nautical miles accelerating or in heavy seas. Th is led to In common with previous Royal
at 16knots and a ship operating profi le the selection of the 5400kW/1000 rpm Netherlands Navy warship procurements,
estimating 20 per cent of operating time MAN 12V 28/33 D diesel, two of which the DMO is taking responsibility for
at ‘loiter’ speeds (0-5 knots), the DMO drive Rolls-Royce fi ve-bladed controllable the supply, test and integration of the
was faced with choice of propulsion pitch propellers through Renk Type ASL SEWACO, and is also procuring weapon
configurations. Its analyses gave 85 double helical reduction gearboxes. systems for the PS programme (supplied
consideration to the ship’s ability to loiter Three 968kW/1800rpm Caterpillar to the shipbuilder as Government
for extended periods, to minimising 3508B generators (two in the aft engine Furnished Equipment [GFE]). It is also
life-cycle costs (of which 80 per cent is fuel room and one in the forward machinery taking responsibility for the delivery of
costs), to the reliability of the propulsion space) will supply electrical power (440 the integrated mast to Schelde, having
train and initial investment costs. V) to support ships services and low speed separately contracted Th ales Nederland
Three propulsion machinery electrical propulsion (service demand for its design, development, production,
arrangements were studied in detail, can be met from just two generators with integration and test.
namely direct drive diesel (where diesels the third in maintenance or on standby). Armament is limited to medium- and
drive shaft s directly through gearboxes); A single 255kW emergency generator small-calibre guns, also supplied as GFE,
diesel-electric (using diesel generators will also be fi tted. to fulfi ll self defence and constabulary
to power an integrated electric plant); A comprehensive load balance has been requirements. Each ship will be fi tted
and a diesel-hybrid confi guration where produced to plot the load from harbour with a single Oto Melara 76/62 Compact
a direct drive arrangement is supported conditions to full electric propulsion gun, plus a single remotely-operated
by an electro-motor power take-in (PTI). (at full electric propulsion both electro- small-calibre gun (27-30mm) and two
DMO found in favour of the diesel hybrid motors will have the equivalent power 0.5cal remote control machine guns (with
arrangement, the requirement to be able of one propulsion diesel at around provisions for two more). Th e DMO is
to sail at low speed for extended periods 20 per cent load). The PTI’s 400ekW currently assessing bids for the supply of
mitigating against direct drive diesel. electric motors will be of a standard the 27-30mm and 0.5cal mountings. In
However, although electric drive enables induction type coupled directly to the addition, the ships will have mountings
The so-called Enlarged Ship concept has been embodied, extending the size of the hull forward so as to gain benefi ts of better
seakeeping and improved vertical accelerations in the ship’s main operations areas. (photo: Thales)
Warship Technology July/August 2008 21
WTJul-Aug08_p18+19+20+21+22+23.indd Sec2:21 7/22/08 7:14:10 PM
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