accident investigation report commercial passenger black ...€¦ · the skipper stopped the vessel...

Accident ReportBlack Cat

Mechanical Failure & Grounding at Akaroa Harbour on

17 April 2005 Class A

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Maritime New Zealand Investigation Report

REPORT NO.: 05 3718

VESSEL NAME: BLACK CAT

Ship Type: Restricted Passenger Vessel

Certified Operating Limit:

Inshore Limits Banks Peninsula

Port of Registry:

Akaroa

Flag:

New Zealand

MSA No.:

126264

Built: 1993, Australia

Construction Material: Aluminium

Length Overall (m): 17.35

Registered Owner:

Black Cat Group Limited

SSM Company:

Maritime Management Services (MMS)

Accident Investigator: Zoe Brangwin

Black Cat

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SUMMARY During an Akaroa Harbour cruise Black Cat suffered a throttle failure whilst manoeuvring close to

shore. The vessel’s starboard bow collided with a rock ledge ahead, the vessel then swung to port and

the starboard propeller struck the rocks. The vessel maintained its watertight integrity and headed

slowly back to the main wharf to unload its passengers. The failure was due to a broken gear select

morse cable.

The report concludes that the morse cable filament wire broke due to metal fatigue, because of cyclic

unidirectional bending when the gear was operated.

• “The stainless steel filament wire failed from fatigue crack initiation and subsequent crack

propagation during service following cyclic unidirectional bending when gear operates.

Fracture occurred at the region where the filament wire is constrained at the actuator box

sheath clamp and the relatively unrestrained red polymer flexible sheath.”

The report recommends that the morse cables be more suitably supported to prevent any further

unidirectional movement and reduce overall stress to the filament wires.

• “Improved service life can be achieved by reducing stress concentration effects at the region of

failure. This can be readily achieved by supporting the Morse cable polymer sleeve in a

horizontal plane for 100-150mm away from the actuator box cable fastening. This would

eliminate unidirectional bending of the filament wire at a region of potential stress

concentration.”

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NARRATIVE Black Cat Built in 1993, launched in 1994. The vessel was a Whitsunday Island passenger vessel prior to being purchased by Black Cat Group Limited and brought to New Zealand in 1999. Black Cat operated out of Lyttelton until October 2004 when she was transferred to Akaroa to take over the Akaroa Harbour Cruise. In October 2003 they replaced Black Cat’s Caterpillar engines with six-cylinder turbo charged twin 522 kW Yanmar engines. At the same time they replaced the engine controls. At the time of the accident the starboard engine had run for a period of 2,160 hours since replacement. Black Cat was kept in Lyttetlon for a year before being transferred to Akaroa in 2004. The vessel’s cruising speed was 20 knots. Black Cat has a valid Safe Ship Management (SSM) Certificate with Maritime Management Services (MMS). The Certificate was issued on 1 October 2003 and expires on 28 August 2007. The vessel is fit to carry 99 passengers and ply inshore limits, Banks Peninsular. Black Cat’s minimum manning required a Skipper and one deckhand. Owner Black Cat is operated by Akaroa Harbour Cruises, which is owned by Black Cat Group Limited. The owners formed the company in 1985. The company started in Akaroa under the name of Akaroa Harbour Cruises. They have since expanded to both harbours and now own and run six vessels out of Lyttetlon and Akaroa. The company prides itself on being an eco-tourism operator. The company changed its name to Black Cat Group Limited in 1999. Black Cat Group Limited carry about 100,000 passengers a year and have about 30 part time and full time employees (this varies dependent on season). Skipper The Skipper, aged 31 years, holds an Inshore Launch Master’s (ILM) Certificate obtained in September 2004, and previously held a Local Launch Operators (LLO) Certificate obtained in 2002. He held a Comprehensive First Aid Certificate. He has been an employee of Black Cat Group Limited for four and a half years working out of Akaroa. He has been the Skipper of Black Cat for six months and had previously operated Canterbury Cat, Clipper and Cat 2 in Akaroa since 2003. The Skipper is a permanent employee of Black Cat Group and works a regular schedule of five days a week between 0900 and 1800 hours. At the time of the accident he had been working for two and a half hours. That week he had worked from Tuesday 12 April through to Saturday 16 April. The day of the accident was his rostered day off, however he was standing in for another Skipper. The Skipper had received training from both of the company’s Head Skippers. Before he took over as Skipper of Black Cat he underwent two weeks of training in the operation of the vessel. This training was documented on the vessel induction forms.

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Crewmember The Crewmember has been an employee of Black Cat Group Limited for nine years. She held a Restricted Radio Operators Licence and a Comprehensive First Aid Certificate. At the time of the accident she had crewed Black Cat two days a week for six months and prior to that eight years on Canterbury Cat. The crewmember had been trained in the operation of the vessel. However, she had not signed an induction sheet for Black Cat as they had been introduced after she joined the company. The Akaroa Harbour Cruise The Akaroa Harbour Cruise is a two-hour eco tourism cruise around Akaroa Harbour and out to the Akaroa Heads, (and further if the weather permits). The cruise boasts dolphins, penguins, seals and marine bird life as well as, “Majestic Scenery including a beautiful harbour and huge volcanic sea cliffs.” Navigation & Safety Equipment • 2 x VHF radios • Coastal lifejackets • Radar • Life rings • GPS • Karly floats • Echo sounder • Fire extinguishers • Autopilot • Bilge alarms • Public Address System (PA) • 24 volt bilge pumps • Cell phone • 230 volt bilge pumps run off the generator in the port hull • EPIRB • Mechanical bilge pumps run off the port main engine • Flares • First Aid Kit Helm Position The vessel has four helm positions: at the central helm position; on the port and starboard bridge wings and on the bow. The bridge wing controls were not covered and therefore exposed to the elements.

Photograph 1 – Port Helm Twin Lever

The port bridge wing control was replaced in March 2005 due to a faulty lever (the lever would not indicate that it was in neutral). This fault was not related to the morse cable failure. Since the accident both bridge wing controls have been replaced and helm controls are now fully covered.

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Control System The vessel’s control system is an electronic Twin Disc Power Commander installed in 2003 during an engine refit. The Control system runs on a system of electrical cables from the helm stations to the junction box where it is transferred to the mechanical push pull action of the morse cable to the engine gear select lever.

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THE ACCIDENT At approximately 1000 hours New Zealand Standard Time (NZST) on 17 April 2005 the Skipper and crewmember of Black Cat boarded the vessel. They completed their pre start checks before taking the vessel to the main wharf to embark the first passengers of the day. At approximately 1105 hours, Black Cat left the main wharf at Akaroa with the Skipper, Crewmember and 31 passengers onboard (28 adults and 3 children). The vessel was on a two-hour harbour cruise. As the vessel left the wharf the Skipper gave a safety briefing over the public announcement (PA) system. He informed the passengers where the lifejackets, life rings, floats, and fire extinguishers were located. He told them to keep their feet on the deck, hold onto handrails and if anything should go wrong to listen to him and the crewmember. He also stated that there was radio equipment and a cell phone onboard. He then informed the passengers about what they would see during the trip.

Figure 1

Main Wharf

Accident Site

Safety Briefing

Scenery Nook

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The weather conditions on leaving the wharf were described by the Skipper as, “southerly five knots and cloudy”. On the way to the heads they encountered a pod of dolphins and spent about 20 minutes watching them. As they reached the harbour entrance the wind increased to 10 knots from the southwest. The Skipper decided not to take the vessel to Scenery Nook as there was “a bit of a slop” and he did not want the passengers to be uncomfortable. They continued the trip and headed towards Seal Bay to find the seals. As they approached the bay they saw more dolphins. The Skipper stopped the vessel and reversed the propulsion system without problem. They stayed there for a few minutes and then continued at idle as the dolphins were swimming across the bow. As they entered Seal Bay the Skipper sighted two seals on a steep to ledge. He continued towards them at idle until he was about 50- 60 metres off the shoreline. The Skipper was on the port bridge wing. He then put both engines astern. The port engine went astern but nothing happened on the starboard engine, which was still going ahead. The Skipper then engaged the starboard engine astern again. This time the vessel leapt forward with full ahead power on the starboard engine. The Skipper used full port throttle to try and turn the vessel before it struck the rock ledge. He yelled down to the passengers on the bow to hold on. Most passengers managed to hold on to the railings.

Photograph 2 – Digital Photograph of Black Cat’s chart indicating position of accident Black Cat’s starboard bow struck the rock ledge with reasonable force. The Skipper stopped the starboard engine (using the emergency stop at the main helm position on the bridge). He then manoeuvred the bow off the rocks with the port engine. The starboard stern quarter hit the rocks as he took this action. As a result of a light breeze coming down the hills combined with a slight swell, the Skipper managed to manoeuvre away from the rocks and into clear water. Once in open water the Skipper remotely started the 230-volt bilge pumps for the starboard hull.

Seal Bay Accident site

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After the accident the crewmember (who was on the bow at the time) led the passengers back into the main cabin. She mustered the passengers and helped them put on lifejackets. The passengers were then seated. The crewmember checked for casualties and discovered that there were a few passengers with minor injuries. The passengers remained very calm after the accident and during the return to Akaroa Wharf. The Skipper stopped the vessel and went into the main cabin to check that everyone was all right. He inspected the void spaces, where were found to be dry. He then informed the passengers that they had experienced an engine malfunction and that they and the vessel were in no danger. The Skipper went back to the bridge and rang the Operations Manager at Akaroa to inform her of the situation. He asked her to have a doctor on standby when they arrived at the wharf in case there was anybody that needed to be seen and in case anyone was suffering from shock. The Skipper also informed the company Managing Director. The Skipper took the vessel back to the main wharf at about five knots. During the return passage he intermittently checked the void spaces to ensure there was no water ingress. Black Cat reached the wharf at 1315 hours. The Skipper berthed the vessel on the south side of the wharf utilising the southerly breeze to assist in bringing the vessel alongside. The passengers were shaken but there were no serious injuries. Seven passengers were taken to the Medical Centre to be seen by the Doctor, and then released. No one was admitted to hospital. Black Cat was taken to Lyttelton the next day to undergo repairs.

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COMMENT & ANALYSIS Damage

• The vessel sustained damage to the starboard hull, propeller and shaft. • Broken gear select morse cable • Damaged starboard propeller • Bent starboard shaft • Dent in starboard bow above waterline • Crack in Z bow below waterline causing small leak

Photograph 3 – Damage to starboard hull

Photograph 4 – Damaged starboard propeller

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Morse Cable After the accident it was found that the gear select morse cable from the junction box to the gearbox had broken. It broke 75mm from the crimped sleeve exit point (marked C, see Photograph 5). The gearbox end was found in the ahead position. The cable was a 4.25 metre Teleflex morse cable with a 1.9mm diameter stainless steel wire filament. The outer sheath was coated with a red polymer. The filament wire was the single element stainless steel wire. Filament breakage occurred at point X (Photograph 6).

Photograph 5 – Filament wire showing broken piece of wire (point ‘C’)

Photograph 6

C

X

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Photograph 7

Gear box showing the gear select lever in the ahead position as it was found after the accident Independent Consultant’s Report Maritime New Zealand commissioned Metallurgical and Industrial Consultants Limited (MIC) to examine the failed morse cable and determine the likely cause of breakage. The following are pertinent extracts from the engineers report.

‘It was stated that the filament wire moves approximately 35mm from neutral to forward and 35mm from neutral to astern at the twin disc actuator. The location of filament wire fracture is directly at a region of constraint where the filament enters and leaves the external fitting crimped to the red polymer outer sheathing.”

Forward – Neutral Neutral - Astern

35mm 35mm

70 mm

“Filament wire fracture has occurred at the actuator box end and the location of fracture is at a point where the filament passes through a 6mm long orifice constraint at the outer sheath as shown by dotted lines.”(See Photograph 8)

Photograph 8 – Actuator end of cable with broken filament. Not to scale.

Gear lever

6mm

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Photograph 9 – 6mm orifice in outer sheath

“View of undamaged end of filament wire (W), Crimp (C), and actuator fitting (F). Outer sheath crimp (O) and delivery tube (T) into which fits the end section of the filament between C and F (see Photograph 10 below).”

Photograph 10

“The morse cable filament is moderately restrained at the actuator box connection (Photograph 11). This is at a location of approximately 200mm between the point where the filament wire is attached to the gear select arm and the outer sheath is attached to the actuator body.”

6mm

F

O T

W C

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Photograph 11 – Junction box showing gear and throttle actuators “Rubbing contact between the wire and crimp can only occur if the red polymer sheath is not horizontally aligned with the crimp fastenings, approximately 100mm from beyond the actuator box fastening.” ”Beyond the actuator box the outer sheath and filament are unrestrained.”

Photograph 12 – 6mm orifice in outer sheath

“The lines marked on the non-fractured end of the filament wire (Photograph 13) identify surface abrasion marks where the wire has been rubbing contact with the outer sheath orifice region above (Photograph 12). This coincides with the failure site at the actuator end of the filament.”

200mm

6mm

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Photograph 13 – Showing each end of the filament wire

Photograph 14 – Enlarged section of above Photograph

“Crack initiation has occurred at the bottom of the macro-photograph (red arrow) and propagated towards the white dashed line. The remaining portion of the fracture face is consistent with overload rupture, (Photograph 15).”

Photograph 15 – Fracture face at the actuator end of the morse cable There was no evidence of any material or manufacturing defect in the filament wire at the region of fracture. The consultants cut a length of the filament wire for tensile testing. The load at failure was recorded at 450kg, which equates to Ultimate Tensile Strength of 1550Mpa. This is more than adequate for its intended purpose.

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Comments on the Draft Report On commenting on the draft report a passenger who onboard who witnessed the event stated,

“The vessel was too close to the rocks for the captain to safely consider turning the bow into the rocks, there was one metre plus following swell which once the bow was tuned into the rocks pushed the vessel forward, this manoeuvre was the principle cause of the accident as it was at that time with the vessel being lifted and pushed towards the rocks that the Skipper was forced to throw the engines into full throttle to exit what was clearly a dangerous situation.” “After hitting the rocks and being able to move off the rocks we were stationary for about 30 minutes plus before slowly proceeding back to the wharf. I was surprised and concerned that no support vessel was requested to assist as I assume at the time the captain was unaware of the cause or the extent of the damage. The fact that we were seemingly not taking water was encouraging however it was impossible at that time to know the true extent of the damage or what effect that would have on our ability to return to shore safely.”

The Owners of the vessel commented as follows:

“Based on the internal investigation by Black Cat Group Limited, together with both the findings of Maritime NZ and TAIC, we feel that these comments are inaccurate. Firstly, the cause of the incident was solely related to the breakage of the morse cable and was not all related to the position of the vessel in relation to the shore; at no point did the Skipper deliberately turn the bow towards the rocks. All investigations cleared the Skipper’s actions and placed the sole blame of the cause of the incident on the morse cable. Secondly, the Skipper thoroughly investigated the damage and found that it was relatively minor (once the vessel was removed from the water, it was confirmed that the damage was minor). At that point, he decided to head back to the wharf, and not to call for back up. Investigations have shown that this was the correct course of action in the circumstances”.

Injuries There were no serious harm injuries. Seven passengers reported sustaining minor to moderate injuries and were seen by a Doctor at the Akaroa Medical Centre. The injuries were as follows:

• Sprained knee • Painful left hand little finger (recommended to have an x-ray when home in Singapore) • Bruised elbow • Suspected Cracked rib • Slight back strain • Bruised left hip • Bruised arms • Two days after the accident a passenger contacted Black Cat Group and complained of a

bruised arm and stiff neck. The company took the names and details of all passengers who sustained injuries as a result of the accident. All other passenger names were recorded on their reservations system and as they were refunded their names were deleted from the computer system. Training All new employees with the company go through induction training. This is documented, signed and kept on file.

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All Skippers are required to read the vessel’s Safe Ship Management (SSM) manual and hazard register and sign that it has been read. The Skipper had signed the SSM manual. The hazard register was kept ashore. The crewmember had not signed the induction sheet as she had joined the company before the written induction process was started. All employees are given a company handbook/operations manual containing a summary of hazard identification. Black Cat Group Limited offer their employees ongoing professional maritime training, i.e., first aid, skippers certificates, engineering courses, fire fighting training. Drills The Skipper of Black Cat and the owner stated that they practise emergency drills. However there is no formal record of drills being carried out. The crewmember stated that she had not been involved in an emergency drill onboard since 2004. Although the Skipper stated that they had been carrying out drills, the drills had not been documented in the ship’s log as required.

Photograph 16 – Extract from ship’s log, written on the back page of every daily sheet

Hazard Identification The company and vessel hazard identification register did not specifically identify machinery/equipment failure as a hazard. Section 7 of the Health and Safety in Employment Act 1993. 7. Identification of hazards

(1) Every employer shall ensure that there are in place effective methods for—

(a) Systematically identifying existing hazards to employees at work; and (b) Systematically identifying (if possible before, and otherwise as, they arise) new hazards

to employees at work; and (c) Regularly assessing each hazard identified, and determining whether or not it is a

significant hazard. The company held a centralised Health and Safety Manual, which was still in draft format. The manual held separate hazard identification for each vessel. The vessels including Black Cat did not hold their own copy of the hazard identification sheets. Therefore there was no system to automatically up date hazards onboard as they are found/identified. The crew had not had any input into the production of a working, up to date hazard register.

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ACTION TAKEN Black Cat Group Limited carried out their own internal investigation and has initiated the following points: Engineering

• The control system morse cables have been replaced onboard Black Cat with Morse supreme cables.

• These morse cables will be replaced every two years. • They have installed emergency stop buttons on the bridge wings. • They have installed covers on the bridge wing controls. • A system has been installed to create less bend in the cables and therefore minimise the

unidirectional bending of the filament wires within the cables. Training

• Implemented training procedures to ensure that emergency drills are carried out at regular intervals onboard all of their vessels.

• Training drills will now be entered correctly in the ship’s log and recorded in the Safe Ship Management Manual.

• Drills on letting go the anchor quickly and manouevring with one engine will be carried out on a regular basis and will form part of the ongoing drills along with the other required drills (fire, man overboard etc).

• In house group training will be carried out twice a year to ensure all staff are up to speed with health and safety and emergency drills.

Documentation

• The Safe Ship Management Manuals have been updated and tailored to each vessel. • Hazard registers have been updated, signed and placed onboard each vessel. • A system has been put in place to ensure the hazard register is updated on a regular basis. • Implemented procedures to ensure that the Safe Ship Management system is reviewed and

updated on a regular basis. This is to be documented in the SSM manual.

Analysis of Morse Cable Breakage

• Black Cat Group ascertained that under normal usage the cables had a life of 150,000 movements and had only done an estimated 30,000 movements.

• The company’s engineers confirmed that they felt the cable set up was not outside the manufacturers recommendations.

• The same morse cable set up had been in place for 10 years without breakage in that area.

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SAFETY RECOMMENDATIONS The Metallurgical and Industrial Consultants Limited (MIC) report recommends that:

“Improved service life can be achieved by reducing stress concentration effects at the region of failure. This can be readily achieved by supporting the Morse cable polymer sleeve in a horizontal plane for 100-150mm away from the actuator box cable fastening. This would eliminate unidirectional bending of the filament wire at a region of potential stress concentration.”

1. It is therefore recommended that the morse cables on Black Cat are securely clamped to the

junction box at least 100mm past the actuator box cable fastening to ensure that the filament does not rub against the outer sheath and therefore minimise metal fatigue.

2. It is recommended that Black Cat Group Limited conducts checks to ensure that this problem

does not exist on any of their other vessels. 3. It is recommended that special attention should be focused on establishing that the cables are

securely clamped to avoid vibration and resultant metal fatigue problems during maintenance inspections on Black Cat Group vessels. This to be implemented within two months of the final report being issued.

4. It is recommended that Black Cat Group Limited change their operating procedures to include

the checking of the helm positions as part of the daily start up checks, on all vessels. 5. It is recommended that the two Skippers of Black Cat be censured for failing to ensure the drills

were documented in the Ships log. 6. It is recommended that Maritime Management Services be censured for failing to audit Black

Cat correctly with respect to vessel training and documentation.

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