Download ART 100-42 Class infield support Rotortugs® for KT

ART 100-42 Class infield support Rotortugs® for KT
Maritime Fitting out at ASL shipyard in Singapore
3 ART 100-42 Rotor tugs fitting out at the ASL shipyard in Singapore with on the left seen the RT
BEAGLE BAY and on the complete right only the bow visible the RT ROEBUCK BAYand in the middle
the RT KURI BAY These vessels will support the Prelude FLNG project off the northwest coast of
Australia and are being constructed for KT Maritime Services Australia Pty Ltd ( a joint venture of
KOTUG International B.V. and Teekay Shipping Australia Pty Ltd).
These innovative vessels were designed by Robert Allan Ltd. in close collaboration with KT Maritime
and will be the world’s first purpose-built FLNG ISVs. They will be powered by the patented
Rotortug® technology featuring three separate azimuth propulsion units (2 forward, 1 aft).
The tugs will measure 41.95 m by 16.00 m and develop over 100 tonnes bollard pull both ahead and
astern.
The ART 100-42 Class ISV is a modern high performance tug custom designed to meet Shell’s
demanding requirements.
The initial concept design for this project was developed by Robert Allan Ltd in direct consultation
with Shell Shipping (STASCO) in London.
The vessels will be tasked with servicing Prelude’s LNG, LPG and condensate export activities, as well
as forming an integral part of the facility’s security, emergency response, and evacuation
requirements. Key duties include:
•escorting, berthing and un-berthing operations (working off either the bow or the stern)
•FIFI Class 1 capability
•floating hose handling operations
•pilot transfer
•security activities
•rescue and emergency evacuation capability
The design of this unique vessel type presented some interesting design challenges to meet Shell’s
functional requirements. A Rotortug’s unique ship docking operation performs ship handling off of
either the forward or the aft deck with large wrap angles of the towlines.
However, this Rotortug had to also be arranged for all the other operational and emergency duties.
This created quite a challenge in suitably arranging key equipment such as Fast Response Craft,
Dacon scoop and deck crane, deck cargo crash rails, and hose handling equipment while not
compromising towing operations.
Some innovative solutions were thus required such as an 800 mm diameter vertically retractable
towing staple and creative arrangements of hose handling equipment.
High environmental standards required all fuel oil, lube oil, and other pollutants to be located off the
shell. This was extremely challenging for a 42 m vessel with fore and aft propulsion systems coupled
with the very high fuel oil and fresh water capacity required for a 35 day offshore endurance, with
reserve.
Shell also required the vessels to be able to operate in fairly significant environmental conditions.
The Robert Allan Ltd. “RAstar” style hull form was thus selected due to its proven seakeeping
performance in high sea states.
The RAstar hull form provides considerable reduction in motions and accelerations compared to
more standard wall-sided hull forms. To confirm the performance, an extensive model testing
program was conducted.
The hull demonstrated excellent sea keeping ability in all sea statesTo ensure that Shell’s bollard pull
requirements were met with the triple drive arrangement Computational Fluid Dynamics (CFD)
analysis was used to optimize the arrangement of propulsors for achieving optimal bollard pull in
both directions.
The best possible visibility from the bridge is critical for day to day ship handling, hose handling, and
pilot transfer operations as well as for emergency operations such as FRC deployment and Dacon
scoop rescue.
Thus, a detailed wheelhouse visibility study was conducted to ensure the clear sightline requirements
were achieved. The Starboard forward quarter view shown below is an example demonstrating
excellent visibility to the winch/staple, fenders, and forward side of vessel. As is typical with all
Robert Allan Ltd. designs, Finite Element Analyses (FEA) of all critical structural foundations were
conducted to ensure that these are fit for purpose.
Below is an image of the forward winch and staple foundations for one of the applied load cases.
https://www.flickr.com/photos/33438735@N08/24272915791
The unique requirements of the Shell Prelude FLNG operation required a unique custom design
solution that could perform the many critical support role and demanding functional requirements.
Robert Allan Ltd. took the design challenges to heart in developing the unique and innovative ART
100-42 ISV design capable of satisfying an extremely demanding set of performance criteria. For
more information on the ART 100-42 Class tugs, or any other high-performance vessel designs
developed by Robert Allan Ltd., please contact [email protected].