LamaLo Technology Inc.
Icebreakers
CGCS
Louis S.
(i)
Assist
in the design and operational considerations for the new propellers
(ii)
Conduct
the theoretical shaft alignment and vibration analyses.
(iii)
Measure
the shaft alignment condition and torsional vibration characteristics.
(iv)
Conduct
the dynamic simulation of entire propulsion system to determine the control
system changes required and the ability of propulsion system to meet
performance requirements with the new propellers fitted. LLT managed and directed the simulation work
and reporting. The computer simulation
programming was sub-contracted.
Measured
Shaft Torque During Ice Milling by Propeller
Corresponding
Measured Shaft RPM
The new propellers were fitted in the
spring of 2000. LLT directed the Sea
Trials and Ice Trials, and measured the shaft power and torsional vibration
characteristics. The propulsion system
performance and the alignment and vibration characteristics were acceptable,
and significantly better than the original propellers.
Prior to a drydocking of the vessel, a
condition assessment of the shaftline was conducted to provide sufficient
justification for the delay of inspection of the centerline shaft beyond the
required 5-year period. This resulted in
savings of approximately $100,000.
USCG Polar Class
Stern of Vessel
USCGC Polar Class
(3 x 20,000 HP): The
LamaLo Technology was contracted to develop a permanent repair and/or
redesign that would effectively address the loss of fit as well as provide for
a reliable bearing. The USCG asked that
the study focus on the potential of chocking the bearing shell in permanently
with a suitable material. The bearing
design arrangement was examined, with particular attention to considerations
for ice-class service. The properties of
potential bedding, filler (between lands), and bearing materials were
assessed. Modifications to the bossing
and bearing length were also examined.
The recommended
modifications to the aft sterntube bearing were implemented on the
Icetech 2006 – Banff, Alberta, Canada Paper – PDF File
Wing Shaft
Stern Bossing
CCG Terry Fox (2 x 6,714 kW): The CCGS Terry Fox is a CAC 4 Icebreaker, and
has a twin screw propeller configuration, each rated at 10,900 HP (8,090
kW). In March 2003 the port middle
lineshaft bearing failed in service. The
bearing babbitt was wiped as well as cracked and de-bonded from the bearing
casing. A new bearing was procured and
installed. The alignment measurements
indicated that alignment was satisfactory and had not changed significantly
since June 1999. The failure of the
bearing was attributed to a decrease in the strength of the babbitt, and the
bond of the babbitt to the bearing casing, after the bearing was slightly
damaged in 1999. Since the lineshaft
bearings are subject to higher forces than convention non-ice class lineshaft
bearings, and were over 20 years old, further failures of lineshaft bearings
could be expected. Therefore, it was
recommended that other bearings be visually inspected to determine if the
babbitt is degrading or de-bonding from the bearing casing. It was also recommended that a spare bearing
be kept on board, along with the tools required to replace a bearing at sea.
Other Work: Mr. Bruce Cowper of LamaLo Technology Inc.
has worked for over 15 years on measurement, analysis, and design of ice class
propulsion systems, including research work used in the development of design
criteria for ice-class propulsion machinery.
This has included working with IACS on the development of Unified
Requirements for Polar Ships, and with the