LamaLo Technology Inc.
Tugs
and Offshore Supply Vessels
Vessels – Non Z-Drive
Crowley Tugs: (2 x 5,467 HP): VTHalter
Hull C-176 Class Tugs are under construction for Crowley
Maritime. The vessels have an overall
length of 127' and have a twin screw propulsion configuration. Each of the 5 bladed fixed pitch propellers is
directly driven by a diesel engine, with a rating of about 4080 kW at 1000 RPM,
through a single reduction reversible gearbox.
The propulsion shaft is approximately 45' long, and is supported by two strut
bearings. The main gear shaft is
supported by two bearings. LamaLo
Technology Inc. (LLT) was contracted by VTHalter
Marine to assist with the propulsion shaft alignment. LLT conducted a theoretical alignment and
lateral (whirling) vibration analysis and also measured the alignment condition
using the strain gauge technique after the vessel was afloat prior to chocking
the gearboxes. The shafting systems for
the first two tugs were installed in 2007.
These vessels have operated without incident.
MV Harvey War Horse (2 x 5,000 HP): MV Harvey War Horse II is
under construction by Eastern Shipbuilding
Group. The vessel has an overall length of
145' and has a twin screw propulsion configuration. Each of the 4 bladed fixed pitch propellers
is directly driven by a diesel engine, with a rating of 5000 HP at 900 RPM,
through a single reduction reversible gearbox.
The propulsion shaft is approximately 49' long, and is supported by a
strut and sterntube bearing. The main
gear shaft is supported by two bearings.
LamaLo Technology Inc. (LLT) was contracted by Eastern
Shipbuilding Group to assist with the
propulsion shaft alignment. LLT
conducted a theoretical alignment and a lateral (whirling) vibration analysis,
and provided final alignment using the strain gauge technique.
MV Seabulk Luanda (2 x 2,970 kW): The MV Seabulk Luanda,
a 65m Anchor Handling Supply (AHS) vessel, and was constructed at Labroy
Shipyards in Batam,
Indonesia. The vessel has a twin screw propeller
configuration. Each of the 4 bladed controllable
pitch propellers is directly driven by a MAK 9M25 diesel
engine with a rated power of 2,970 kW at 750 RPM, through a single
reduction reversible gearbox (4.839:1). The
propulsion shaftline is approximately 17.5 m long, and is supported by an aft
and forward sterntube bearing, and an intermediate shaft bearing. The main gear shaft is supported by two
bearings. LLT conducted a theoretical
alignment and a lateral (whirling) vibration analysis, and provided final alignment
using the strain gauge technique. The vessel
was delivered in 2005 and has operated without incident.
MV Julia (2 x 3,505 HP): The MV Julia is a 120' twin screw Tug that was
delivered in 1998. Each of the 5 bladed
fixed pitch propellers is directly driven by a diesel engine, with a rating of 3505
HP at 900 RPM, through a single reduction reversible gearbox. The propulsion shaft is approximately 35'
long, and is supported by a strut and a sterntube bearing. The main gear shaft is supported by two
bearings. High shaft vibrations were
reported on this class of vessel shortly after delivery and damage/failure of
the propeller shafting occurred. The
propeller shafts were then replaced with higher strength shafts, and the vessel
ran without incidence until 2006 when a broken pinion tooth on the starboard
gearbox was detected and scuffing of pinion teeth was observed on the port
pinion teeth. Both port and starboard
pinions were replaced and the starboard bull gear was replaced. LamaLo
Technology Inc. was contracted to investigate the source of the pinion failure,
conduct a theoretical finite element analysis of the alignment and whirling characteristics
of the shaftline and assess the design arrangement. Strain gauge alignment measurements and
analysis were also conducted. Recommendations
for realignment were provided.
MV Joy Anne Keller (2 x 4,000 HP): The MV Joy Anne Keller (Keller), a 180'
T.S. Tow Boat that operates on the Mississippi River. The Keller was built in 1999 and has a gross
tonnage of 1061. The vessel has a twin
screw propeller configuration. Each of
the 5 bladed fixed pitch propellers is directly driven by a diesel engine with
a rated power 4000 HP at 900 RPM, through a single reduction reversible
gearbox. The propulsion shaftline is
approximately 43' long, and is supported by a strut and stern bearing
(outboard), and a lineshaft shaft bearing.
The main gear shaft is supported by two bearings. LamaLo Technology Inc. was contracted to
investigate the source of a main gear pinion failure. A theoretical finite element analysis was
conducted of the shaftline and the design arrangement was reviewed. Strain gauge alignment measurements and
analysis were also conducted. The
propulsion shafting was found to be severely misaligned to the gearbox, such
that the aft gearshaft bearing load was over-loaded and the forward bearing was
top-loaded. This misalignment was
considered to be the source of the pinion failure. Recommendations for realignment were provided
and implemented.
MV Seabulk Vung Tau Class (2 x 2,540 kW): The
MV Seabulk Vung Tau, a 63m Anchor Handling Supply (AHS) vessel, is under
construction at Labroy Shipyards in Batam, Indonesia. The vessel is a first of four “E” class
vessels. It has a twin screw propeller
configuration. Each of the 4 bladed
controllable pitch nozzled propellers is directly driven by a diesel engine
with a rated power of 2,540 kW at 750 RPM, through a single reduction
gearbox. To reduce the risk of
propulsion shafting problems LamaLo Technology Inc. (LLT) was contracted by
Seabulk International Inc. to provide an independent theoretical shafting
alignment analysis, to review the design arrangement, and to provide strain
gauge alignment analysis. The shipyard
was to provide the strain gauge alignment measurements for LLT to assess.
MV Venture Sea - Offshore
Supply Vessel: (2 x 7,000 HP Nozzled CP Propellers): The MV Venture Sea was delivered in 1998/1999
and operates out of Dartmouth,
Nova Scotia. Excessive vibrations were experienced since
delivery of the vessel, and the port propeller shaft broke off at the propeller
flange in the fall of 1999. The
vibrations were attributed to excessive shaft whirling as a result of a
misalignment of the propulsion shaftline such that the stern tube bearing was
unloaded. The shaftlines were re-aligned
in January 2000. However significant
structural vibrations were still present.
Cracks in the structure around the nozzle and on the deck coverings also
occurred. LamaLo Technology Inc. (LLT)
was contracted to measure and assess the installed propulsion shaftline
vibration characteristics, to determine if the vibrations are potentially
harmful to the machinery components, and if so, what would be the recommended course
of action. It was found that excessive
lateral (whirling) shaft vibrations are present above engine speeds of 700 RPM
during all operations (see plots below).
Subsequent to the vibration measurements, as recommended by LLT, the
maximum engine speed was limited to 700 RPM.
The ship vibrations are reported to be no longer present under this
operating condition, and the vessel still meets its operational requirements
with significant fuel savings.
Range
of Shaft Orbit 700 RPM and Lower Range
of Shaft Orbit 900 RPM
MV Pionero: (2 x 2,000 HP):
The MV Pionero is a 202' Offshore Supply Vessel
operating in the Gulf of Mexico. The vessel has a twin screw propeller
configuration. Each of the five bladed
fixed pitch propellers is driven by one diesel engine rated at 2,000 HP at 1600
RPM, through a 5.5:1 single reduction gear box. A relatively loud noise could
be heard in the aft area of the MV Pionero at lower
shaft speeds (about 650 to 1000 Engine RPM).
The noise appeared to be coming from the area of the strut, either the
propeller or the strut bearing, and seemed to be shaft speed dependent. There was concern that the shafting and
bearings may have excessive forces or vibration that resulted in the
noise. To address this concern, a
project was undertaken to determine if the shafting system had any excessive
vibrations or misalignment, the source of the noise, and to recommend what
action would be required to reduce the noise to acceptable levels. These objectives were accomplished by a
combination of theoretical modeling, design review and assessment, and on-site
measurements. The measurements program
was conducted during dedicated trials in January, 2004, and included the
following:
·
Static alignment using the strain gauge
technique.
·
Shaft torsional vibration using strain
gauges.
·
Shaft whirling vibrations using non-contact
displacement transducers.
·
Machinery and structural linear vibrations
using a hand held vibration meter.
·
A qualitative assessment of structural
vibrations.
It was concluded that the
source of the noise was from the propeller, and was due to resonant vibration
of the propeller blades induced by vortex-shedding from the trailing edge of
the propeller (commonly called “propeller singing”). The trailing edge of the propellers was
modified appropriately. It was found
that the “loud noise” was no longer present in subsequent operations. Below are plots of the shaft torsional
vibration measurements with and without the propeller “singing”.
High Frequency Vibration Present (250 to 300 Hz) –
Noise from Propeller Singing
No High Frequency Vibration– No Noise
Seacor Vision and Vantage - AHTS: (2 x 4,580 HP): Propulsion System Failure
Investigation. Determined cause of failure
of machinery components and least-cost solution. This included measurement of the propulsion
shaft axial, lateral and torsional vibration characteristics and the alignment
condition. Repair and re-alignment work
was done on the Seacor Vantage in the winter of 1999/2000. The Seacor Vision re-alignment was conducted
in the fall of 2000. After this work,
measurements on the vessels indicated acceptable alignment and vibrations. The vessels have been operating since with
not further propulsion shafting failures.
Seacor Gerard Jordan and Vanguard – AHTS: (2 x 7,000 HP): Propulsion system alignment and vibration
measurements and analysis. Shaft alignment
measurements indicated an uneven bearing load distribution. Concern was expressed about the possibility
of excessive lateral vibrations (whirling) of the main gear shaft and the
long-term consequences. To determine if
these vibrations were excessive, the dynamic vertical and horizontal shaft
displacements were measured at the forward and aft end of the gear shaft, and
at the forward end of the propeller shaft.
Dynamic shaft alignment measurements were also obtained using the strain
gauge technique. The measurement results
indicated acceptable shaft lateral vibrations throughout the operating profile
of the vessel. Example plots are shown
below. No failures have occurred to the
shafting system components since the assessment was conducted in 2000.
Unloaded Roller Bearing; Acceptable Vibration Loaded
Roller Bearing; Acceptable Vibration
Project
Descriptions