|Date reported||01 January 2014|
|Concern title||Design of instruments used to drive the ship|
The concern related to the design of the instruments which are used to control the ship's direction and speed.
|Industry / Operation affected||Marine: Shipboard operations|
|Concern subject type||Marine: Ship operations|
These are small twin-screw general cargo ships, but the propulsion is unusual. The ship is fitted with medium speed diesel engines running through reduction and reversible gearboxes. There are no bridge wing controls. There are two boxes both containing two indicators; one box showing engine revolutions and one box showing propeller revolutions. It is difficult to distinguish which propeller is being indicated and which direction the propeller is running.
The quality of the indicators is also poor, as some indicators were not zero when the main engine was shutdown and the propellers clearly stopped. These ships have a two-engine dead slow speed of 9 knots and a sea speed of about 12.5 knots. So there is little margin for error when manoeuvring these vessels using main engines. Also, the stern is very fine and the parallel mid body is short.
There are several latent conditions in the operational control of these ships that will lead to errors in shiphandling. The shape of the ship is most unforgiving should an unplanned contact occur.
The latent conditions include:
- The indicators all look the same and are not intuitively positioned
- The indicators give misleading directive information
- The visibility from the wheelhouse prohibits efficient situational awareness for operation from the controls position
The helmsman on the ship had responsibility for the helm and telegraphs, he operated all the controls on this ship from inside the wheelhouse. He may have also had responsibility for the movement book. The one-man operation inside the narrow poorly designed wheelhouse is dangerously over-reliant on the skills and aptitude of the helmsman.
Operator's response (Operator 1)
No response was received from the operator.
Regulator's response (Regulator 1)
The report makes specific reference to a general cargo ship.
On the basis of the information provided there appears to be areas identified in the report which are subject to statutory requirements. These are:
- Instrumentation to be provided; and
- The requirements related to system and equipment design and arrangements.
This is prescribed in in SOLAS 11-1,
Chapter 11-1 I Regulation. 31 Machinery controls
.2.8 indicators shall be fitted on the navigation bridge, the main machinery control room and at the manoeuvring platform, for:
.2.8.1 propeller speed and direction of rotation in the case of fixed pitch propellers; and
.2.8.2 propeller speed and pitch position in the case of controllable pitch propellers;
Chapter 11-1/ Regulation. 49 Control of propulsion machinery from the navigating bridge
.6 Indicators shall be fitted on the navigating bridge for:
.1 propeller speed and direction of rotation in the case of fixed pitch propellers; or
.2 propeller speed and pitch position in the case of controllable pitch propellers
On the basis of the information contained within the report, including supporting photographs, the vessel has been fitted with the prescribed instrumentation.
Bridge design and layout
The applicable requirements related to bridge and equipment design and layout are contained in Chapter V of SOLAS.
Chapter V Reg. 15 Principles relating to bridge design, design and arrangement of navigational systems and equipment and bridge procedures. All decisions which are made for the purpose of applying the requirements of regulations 19, 22, 24, 25, 27, and 28 of this chapter and which affect bridge design, the design and arrangement of navigational systems and equipment on the bridge and bridge procedures (Refer to Guidelines on ergonomic criteria for bridge equipment and layout (MSC/Circ.982}) shall be taken with the aim of:
- facilitating the tasks to be performed by the bridge team and the pilot in making full appraisal of the situation and in navigating the ship safely under all operational conditions;
- promoting effective and safe bridge resource management;
- enabling the bridge team and the pilot to have convenient and continuous access to essential information which is presented in a clear and unambiguous manner, using standardized symbols and coding systems for controls and displays;
- indicating the operational status of automated functions and integrated components, systems and/or sub-systems;
- allowing for expeditious, continuous and effective information processing and decision-making by the bridge team and the pilot;
- preventing or minimizing excessive or unnecessary work and any conditions or distractions on the bridge which may cause fatigue or interfere with the vigilance of the bridge team and the pilot; and
- minimizing the risk of human error and detecting such error if it occurs, through monitoring and alarm systems, in time for the bridge team and the pilot to take appropriate action.
Noting the reference to MSC Circ. 982 (GUIDELINES ON ERGONOMIC CRITERIA FOR BRIDGE EQUIPMENT AND LAYOUT); this guideline give supporting guidance on the application provisions of the revised regulation V/15 of the SOLAS Convention which entered into force on 1 July 2002 and applies to this vessel. While such guidance is not mandatory section 5.6 may be considered pertinent.
5.6 Information Display
5.6.1 General Display Requirements
188.8.131.52 Lack of Ambiguity
Display indicators should clearly and unambiguously direct and guide the appropriate control response.
Summary with respect to statutory requirements
On the basis of the information reported it would appear that the requirements of SOLAS Ch. V, Reg. 15.3 may have not been completely satisfied on board the vessel given the arrangement does not appear to provide an unambiguous presentation of information.
This conclusion is based on the observation that the propeller pitch indicators on the port bridge wing point in a forward direction when astern pitch is applied. This may be counter intuitive to users, particularly where information on the gauges is not particularly clear, as appears to be the case.
From a human factors perspective this has the potential of increasing cognitive workload whenever the vessel is being manoeuvred from this position, specifically during times of high workload, such as berthing the ship.
This could result in a loss of situation awareness (i.e. breakdown in the process of acquiring and processing task-related information such as misinterpretation of the information presented by the instruments in question) potentially leading to errors.
Responses to other comments in the report
1. Quality of the instruments - The reporter makes reference to the quality of the instruments provided and states that the indicators "were not zero when the main engine was shutdown". Currently there is no legislative requirement in regard to the 'quality' of instruments provided and it is not uncommon for instruments to give what appear to be erroneous indications when systems are shut down and therefore electrically de-energised. These erroneous indications are the result of the physical properties (electrical, magnetic and mechanical) of the instrument and the nature and configuration of the specific electrical system supplying signal information to the instrument. Again there is no specific performance requirement or standard that would require an instrument to indicate a particular value when the electrical systems are de-energised.
2. Latent Conditions - Reference is made to the "latent conditions in the operational control of these ships" in which the reporter states "the shape of the ships is most unforgiving", "the indicators all look the same and are not intuitively positioned", "the indicators give misleading information" and "the visibility from the wheelhouse prohibits efficient situational awareness for operation from the controls position".
Addressing these 4 comments in turn, there is no specific statutory requirement for a vessel to have a particular hull form or handling characteristic. Such requirements are often included in shipbuilding new construction contracts however this is a commercial matter between the buyer and seller and not within the domain of maritime safety authorities.
With respect to indicators and instruments, our response in relation to statutory requirements for instruments and indications has already been provided above.
With regards to bridge visibility, SOLAS Chapter V Reg. 22 Navigation bridge visibility stipulates specific criteria for bridge visibility which includes, inter-alia, arcs of visibility, blind sectors, horizontal fields of visibility from conning and steering positions, navigation bridge height etc. IMO MSC Circular 982 (referred to above) provides additional guidance in this regard. The report, as provided, does not contain sufficient information to definitely ascertain compliance or otherwise with either the SOLAS regulation 22 or the MSC Circular.
Finally, the reporter comments on the duties and responsibilities of the helmsman on board the subject vessel. The composition, duties and responsibilities of individuals forming a navigating watch are governed by the STCW Code Part A, Ch. VI, Part 4 -1. In summary, the Master of a vessel is to give consideration to a number of factors when determining the composition, duties and responsibilities of the bridge watchkeeping team throughout the entire voyage. Based upon the information contained within the report, AMSA is not in a position to objectively assess the suitability of arrangements on board in order to determine compliance or otherwise with these requirements.
In conclusion, there is sufficient objective evidence to raise questions with respect to the ability of the vessel in question to comply with applicable statutory legislative requirements related to bridge design and layout.
AMSA intends to correspond with the vessels Flag State Administration to outline the particular concerns raised and the possible areas of statutory non-compliance. Other issue will be examined as part of a Port State Control inspection when next the vessel is available for inspection in an Australian port.