Section 15 Navigation and manoeuvring systems

15.1.1 The requirements of Pt 6, Ch 2, 15.1 Steering gear 15.1.2 to Pt 6, Ch 2, 15.1 Steering gear 15.1.5 are to be read in conjunction with those in Pt 5, Ch 19, 4 Steering control systems and Pt 5, Ch 19, 5 Electric power circuits, electric control circuits, monitoring and alarms.

15.1.2 Two exclusive circuits, fed from the main source of electrical power and each having adequate capacity to supply all the motors which may be connected to it simultaneously are to be provided for each electric or electrohydraulic steering gear arrangement consisting of one or more electric motors. One of these circuits may pass through the emergency switchboard, see also Pt 5, Ch 19, 6 Emergency power.

15.1.3 The motor of an associated auxiliary electric or electrohydraulic power unit may be connected to one of the circuits supplying the main steering gear.

15.1.4 Any main and auxiliary steering gear electrical control system and steering gear motors operable from the navigational bridge are to comply with SOLAS Ch II-1, Part C, Regulation 29 - Steering gear1, Section 8 and SOLAS Ch II, Part C, Regulation 29 - Steering gear1 Section 5.

15.1.5 In ships of less than 1600 gross tonnage, if an auxiliary steering gear is not electrically powered or is powered by an electric motor primarily intended for other services, the main steering gear may be fed by one circuit from the main switchboard. Consideration would be given to other protective arrangements other than described in Pt 6, Ch 2, 15.1 Steering gear 15.1.4 for such a motor primarily intended for other services.

15.2.1 Where azimuth or rotatable thruster units, used as the sole means of steering, are electrically driven the requirements of Pt 5, Ch 20, 5.1 General are to be complied with.

15.3.1 For ships having a DP notation the requirements of Pt 7, Ch 4 Dynamic Positioning Systems are to be complied with.

15.4.1 Where a thruster unit is fitted solely for the purpose of manoeuvring, and is electrically driven, its starting and operation is not to cause the loss of any essential services.

15.4.2 In order to ensure that the thruster system is not tripped inadvertently whilst manoeuvring the ship, overload protection in the form of an alarm is to be provided for the electric motor and any associated supply converters, in lieu of tripping.

15.4.3 The thruster unit electric motor is not to be disconnected as part of a load management switching operation.

15.5.1 Where transverse thrust units are remotely controlled, means are to be provided at the remote control station to stop the propulsion unit.

15.5.2 Transverse thrust units are to be provided with indications of direction and magnitude of thrust and propeller pitch at each station from which it is possible to control justify the propeller pitch.

15.6.1 Navigation lights are to be connected separately to a distribution board reserved for this purpose only and accessible to the officer of the watch. This distribution board is to be connected directly or through transformers to the emergency source of electrical power in compliance with, for passenger ships, Pt 6, Ch 2, 3.3 Emergency source of electrical power in passenger ships 3.3.1 or, for cargo ships, Pt 6, Ch 2, 3.4 Emergency source of electrical power in cargo ships 3.4.1. An alarm is to be activated in the event of failure of a power supply from the distribution board.

15.6.2 Each navigation light is to be controlled and protected in each insulated pole by a switch and fuse or circuit-breaker mounted on the distribution board.

15.6.3 Provision is to be made on the navigating bridge for the navigation lights to be transferred to an alternative circuit fed from the main source of electrical power.

15.6.4 Each navigation light is to be provided with an automatic indicator giving audible and/or visual indication of failure of the light. If an audible device alone is fitted, it is to be connected to an independent source of supply, e.g. a battery, with means provided to test this supply. If a visual signal is used connected in series with the navigation light, means are to be provided to prevent extinction of the navigation light due to failure of the signal. The requirements of this paragraph do not apply to tugs, trawlers and similar small vessels.

15.6.5 For navigation lights using light emitting diodes (consisting of multiple light sources) means to ensure that the overall luminous intensity of the navigation light is sufficient are to be provided in addition to the alarm to indicate the complete loss of the navigation light illumination required by Pt 6, Ch 2, 15.6 Navigation lights 15.6.4. For replacement navigation lights, see Pt 6, Ch 2, 1.5 Additions or alterations 1.5.5.

15.6.6 To satisfy Pt 6, Ch 2, 15.6 Navigation lights 15.6.5, an audible and visual alarm is to be activated to notify the Officer of the Watch when the luminous intensity of the light reduces below the level required by the IMO Convention on the International Regulations for Preventing Collisions at Sea. Alternative measures to ensure continuing acceptable performance of navigation lights using light emitting diodes may be considered that are in accordance with:

• IMO Resolution MSC.253(83) - Adoption of the Performance Standards for Navigation Lights, Navigation Light Controllers and Associated Equipment - (Adopted on 8 October 2007), and
• EN 14744, Inland navigation vessels and sea-going vessels – Navigation light, or a relevant National or International Standard.

Where alternative measures are proposed that require verification by personnel of the luminous intensity of navigation lights using light emitting diodes, details of the inspection implementation in the ship’s safety management system and acceptance by the National Administration are to be submitted for consideration.

15.6.7 Navigation light power supply units installed to convert, control and/or monitor the distribution board power supply required by Pt 6, Ch 2, 15.6 Navigation lights 15.6.1 above for connection to the light source(s) (e.g. for LED type navigation lights) are, in the event of a short-circuit on the unit output, to disconnect or limit the supply to prevent further damage and activate an alarm.

15.6.8 Navigation light power supply units are to be self-checking, detecting failures of the unit itself and activating an alarm. These are to include:

• detection of system lock-ups (program hangs);
• means to detect failure of navigation light switching command input circuits or links; and
• means to detect failure of the navigation light monitoring arrangements required to provide the alarms required by Pt 6, Ch 2, 15.6 Navigation lights 15.6.4 and Pt 6, Ch 2, 15.6 Navigation lights 15.6.5, as applicable.

15.6.9 The navigation light power supply failure alarms required by Pt 6, Ch 2, 15.6 Navigation lights 15.6.1 are not to be displayed as a group alarm. Other navigation light alarms may be grouped for each navigation light where means are provided for personnel to determine the cause of the alarm. Activation of more than one of the navigation light alarms as a result of a single failure is to be prevented.

15.6.10 Any statutory requirements of the country of registration are to be complied with and may be accepted as an alternative to the above.

15.7.1 Navigational aids as required by SOLAS are to be fed from the emergency source of electrical power, see also Pt 6, Ch 2, 3.3 Emergency source of electrical power in passenger ships 3.3.1 and Pt 6, Ch 2, 3.4 Emergency source of electrical power in cargo ships 3.4.1.

15.7.2 For ships having a notation NAV1 navigational aids are to have an alternative supply fed from the main source of electrical power, independent of the emergency switchboard, with automatic changeover facilities.