Tuesday, April 27, 2010

Integarted Bridge System

An IBS is a combination system which is interconnected to allow the centralized monitoring of sensor information and control of a number of operations such as passage executions, communications, machinery control, safety and security. IBS is basically a combination of INS and other shipboard systems. It reduces work load, provides cetralised control and black box for later analysis.
IBS enhances speed of command by providing more time for decision making and action.

BENEFITS OF IBS:
Navigation; Anti-collision;; Steering; Machinery control; Logging; Voyage recording; Safety and recording.
There is no single standard IBS design for ships nor is IBS mandatory. Classification societies do offer optional class notations for ships; the NAV1 class for LR, the W1-OC class from DNV are examples of class notations for IBS arrangements designed to support periodic one man bridge operations.
Factors including the design of the bridge , the type of equipment that is fitted and the layout of that equipment on the bridge will determine the extent to which the IBS design allows certain bridge functions to be automated.
WORKSATIONS BRIDGE DESIGN AND LAYOUT: Centralized control and monitoring requires a work station design approach. At the main operating position on the bridge, referred to variously as the work station for navigation and traffic surveillance/ maneuvering, the navigation work station or the conning position, the OOW should be able to undertake all his primary duties unassisted with efficiency and safety. The design should also allow two bridge team members to work unhindered side by side.
Bridge design and layout of work stations, together with equipment and instrumentation at those work stations is an important part of IBS design. The IBS design should ensure that the failure of one sub system does not cause the failure of another and any failure is immediately brought to the notice of OOW

IBS EQUIPMENT: To permit centralized control and monitoring of navigational functions on the bridge, the following system will be required:

1. Navigation Management System: The NMS provides the mechanism of planning, executing and monitoring the passage plan and will therefore provide the link between the charts on which the voyage has been planned, the position fixing systems, the log, gyro and auto pilot. An ECDIS will typically function as the NMS within an IBS, supported by dedicated route planning terminal to allow route planning activities to be undertaken while on passage and without interfering with the OOW.
2. ALARM SYSTEM: The IBS has an alarm system to warn the OOW if potentially dangerous situations could arise. Failure of the OOW to acknowledge alarms --- usually within 30 s --- will transfer the alarm to remote alarm units in cabins, offices and messes to call for back-up assistance. The main navigational sensors, in particular the radar which provides traffic alarms, the gyro and auto pilot which provide course related alarms and position fixing systems which provide position related alarms, need to be connected to alarm system. ECDIS, the steering gear, power distribution panels etc may also be connected. Including in the alarm system should be a watch safety or fitness alarm to monitor the alertness of the OOW.An interval timer for setting alarm intervals of upto 12 mins should be part of the system. A number of alarm acknowledgement points, each with a pre-warning alarm to give the OOW notice that the alarm is about to be activated should be available around the bridge. As with the failure of the OOW to acknowledge a navigation alarm, if the fitness time interval expires, an alarm should sound away from the bridge.
3. CONNING DISPLAY: The display should be available at the conning position to
show information summaries of the important navigational sensors on passage and
while docking. He display also provides the OOW with a central place to monitor sensors
and compare actual settings with those ordered. IBS AND THE AUTOMATION OF NAVIGATION FUNCTIONS:
The process of planning a passage through to its execution and monitoring the progress of the ship against the plan is one bridge operation that can be safely automated as long as certain principles and disciplines are followed:
1. the plan needs to be thoroughly prepared on the charts.
2. the details of the plan and particular the waypoints, need to be carefully prepared on or transferred to the navigation system.
3. the position of ship needs to be safely calculated and quality monitored by the navigation system.
4. if the position of ship is accurate and reliable and the passage plan has been safely entered the XTE deviations off track as calculated by navigation system and transmitted to the autopilot will be accurate, and allow the autopilot to control ship’s direction safely and automatically.
USING IBS: Where fitted , clear guidance on IBS operations should be contained in the shipboard operational procedures manual. In particular, advice on when to commence and when to suspend automatic track keeping should be provided. Over reliance on automatic system, coupled with the OOW paying too little attention to visual navigational and watch keeping techniques, can be dangerous.

As per IMO IBS should include (any two) the following:
Passage Execution
Communications
Machinery Control
Loading, discharging and cargo control
Safety and security

INS:
Similar to evolutionary principle in living beings, marine navigation systems are becoming increasingly complex and sophisticated. Both by design and function, shore based and ship based navigation systems are no longer individual equipment components operating independently. The trend is gravitating towards data fusion,
functional synergy and modular integration.
Unlike dedicated ECDIS display INS displays are task oriented composite presentations that enable the mariner to configure the display for an operational situation by selecting specific chart, radar, ARPA and AIS information that is required for the task at hand.
Introduction of ECDIS, availability of accurate position fixing system ( GPS ) and plotting aids (ARPA) and automatic programmable ship’s steering have made the process of INS easier and faster.
INS based on modular concepts which allows a flexible change of a set of navigational facilities depending on ship’s type and area of operation of the ship will have the three modules forming the integral part of the INS:

NAVIGATIONAL MODULE: This module will take care of voyage planning, position fixing on a continuous basis and ARPA plotting functions. This module will perform the following tasks:
Specifying ship’s route and sailing mode
DR by inputs from gyro and log
Position and speed by signals from GPS/DGPS
Position fixing by inputs from terrestrial based radio navigation system
Position and velocity determination using fixed Radar markers
Automatic selection of radio navigation aids on the basis of accuracy criteria
Record and reproduction of cartographic information on a display
Data logging in log book format
Storage of navigational parameters for a given time
Warnings in case of exceeding the prescribed depth, route cross track, approaching critical points including alteration of course etc. and
Automatic correction of charts

ANTI COLLISION MODULE: This module works out the best possible action to be taken in case of close quarters situations on the basis of the following:
Collision regulations
Sea room availability
Trial maneuver
Desired CPA

STEERING CONTROL MODULE: This module is dedicated to steering the ship and will perform the following functions:
Steering a given course, taking into account the ship dynamics, trim etc. and external conditions.
Automatic course alteration in accordance with planned track and
Alterations for collision avoidance and subsequent track keeping.





The basic difference between IBS and INS is that INS is a combination of navigational data and systems interconnected to enhance safe and efficient movement of the ship, whereas IBS interconnects various other systems along with the INS to increase the efficiency in overall management of the ship. In this sense the INS is specific in nature while IBS has a more generalized approach.

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