ship design and role of naval architecture
Purpose of ship design
This technical specification document along with General Arrangement Plan shall describe the characteristics and design intended vessel design.
The vessel shall be outfitted with machinery and provided with equipment according to the latest rules and regulation of the Classification Society for worldwide service and operation. The designed vessel shall also comply with all statutory regulations laid down by the Flag Administration and IMO for such vessels for worldwide operation and suitable service in connection with offshore installations or worlwide transit.
Basic requirement of the vessel shall be defined before design starts
Deck layout shall be suitable for intended operation and cargo holds shall be sufficient for intended cargo carrying.
Ship Design Spiral
Stability
The Vessel shall meet the following codes with respect to stability:
Propulsion system Selection
Propeller sizing
Dynamic Positioning System
These requirement are defend as per DP-3 requirement for easy comprehension. DP-1,DP-2 system shall be configured based on the redundancy philosphy.
The design and philosophy of the DP system shall be developed along with the chosen equipment vendor and shall comply with Classification Society regulations. When designing and detailing the system best industry practices and IMCA recommendations shall be taken into account.
The vessel shall hold position in any of the loading conditions and under the following environmental conditions:
The fully operational Dual Redundant DP system shall keep the vessel in position and system accuracy. The DPS shall comprise of:
The DPS reference systems shall typically comprise of the following
DP system shall interface with the following:
In addition to the basic DPS functions, the following shall be provided:
The system shall include online consequence analysis, online DP capability analysis, motion prediction analysis and DP operation output alarm. Hydro-acoustic positioning unit and sea valve open / close indication shall be available locally as well as in the operation station. The valve shall be gear operated . The valve shall have interlock with the pole up / down controls. As the vessel shall be DPS-3 Classed, an Independent Joystick System (IJS) shall be supplied in addition to the DPS system. Provision shall be made for attaching the independent Joystick in Both Fwd and Aft Control rooms and P/S wings.
Noise and vibration
Suppression of noise shall be given full consideration at the design stage, the final levels of both air and structure borne interference being sufficiently low as to not cause any reduction in specified part performance of any installation equipment.
Bulkheads in accommodation shall give minimum 40dB sound reduction from cabin to cabin and 35dB sound reduction bulkheads in other spaces. Special precautions shall be made for ceiling fastening to avoid noise and vibration. Combustion machinery and hydraulic aggregates shall be installed on flexible mounting joints and shall have flexible pipe connections.
Vibration Levels Reference - ISO 6954 - Guidance notes on acceptable vibration levels and their measurement shall be followed.
The ship shall have sufficient positive stability in all normal conditions of loading and shall comply with the standards as recommended by Regulatory Bodies. The builder shall carry out an inclining experiment in the presence of the Classification Society and authorities, as required. The results of the inclining experiment shall be used in the preparation of Final Trim and Stability Book for the use of ship’s officers. The stability data shall include loading conditions sufficient to cover all normal operating roles. The builder shall submit the completed Trim and Stability Book to the Classification Society and authorities and obtain approval. For more than one vessel of the same class, the inclining experiment shall be carried out for the first vessel only subject to classification and authority approvals. However, a draft survey shall be carried out on subsequent vessels.
HULL AND SUPERSTRUCTURE
The vessel shall be of all welded construction in accordance with contract plans, specifications, and Class Society rules. Hull structure shall meet Classification Society requirements and all steel plate shall be Classification Society certified and stamped.
The steel hull and deck erections shall be of all welded construction.
Longitudinal framing system for bottom, sideshell and decks with deep transverse frames spaced at 1.8m shall be adopted. Scantlings shall be according to the Classification Society requirement for thickness of plate and modulus of sections.
All steel plates, sections, hull-forging and castings shall meet Classification Society requirements and shall be supplied with test certificates where applicable. All smith-work of fabricated fittings shall be of neat design, strong, smooth and free from defects.
Shell Plating and Bottom Structure
The bottom (including bilge strake) and side plating shall be longitudinally plated, shall have welded butts and seams and except in way of openings for sea water inlets, thrusters well, hawse pipes and forefoot, etc. where heavy plates shall be fitted.
Double bottom shall be provided except forepeak and stern propulsion room and in way of deep tank. Inner Bottom shall be stiffened with vent holes throughout to ensure proper drainage and to eliminate entrapment of air pockets. Double bottom where fitted shall have a height of 1800mm
A flat plate keel shall be fitted throughout the bottom of the vessel.
Main Deck
The main deck shall not have sheer and camber. The main deck shall be longitudinally framed and supported by deck girders and deep transverses. The deck plating aft of the superstructure FR 29 to AP shall take uniformly distributed load of 15 tonnes/m2, forward of FR 29 outside of superstructure shall be designed for 5t/m2.
Elsewhere the deck plating shall be according to Classification Society requirements. The deck plating shall be welded direct to the shell. Extra thick insert plates shall be fitted at deck machinery areas, winches, capstans, tugger winch, bollards, fwd and aft, and at anchor pockets.
Watertight Bulkheads
The vessel shall be subdivided by longitudinal and transverse watertight bulkheads as shown in the General Arrangement drawing. Vertical Zones as per SOLAS shall be maintained.
Tanks
Tanks shall be suitable for their intended use. All tanks shall be easily accessible through adequate size and number of manholes. All tanks shall be fitted with ladders or hand grips.
Moonpool
One (1) Moonpool of 7000 x 7000 mm (approx) square clear opening equipped with water column dampening arrangement shall be provided for the launch and recovery of the saturated diving bell and other subsea equipment. The moon pool shall be of an aerated type.
Skeg
A box shape skeg shall be fitted at fore & aft. The bottom of the skeg shall be 15mm, sides and webs shall be 12mm or as required.
Roll Stabilizing Tank (flume tank)
Two (2) anti-roll tank of passive type shall be provided. The tanks shall carry sea water for dampening the roll. The tanks shall be built with a high degree of flexibility and shall be capable of controlling the roll of the vessel for variety of displacement and roll periods.
The roll dampening system shall have an interface with the vessels computerized stability program and shall be able to be continuously monitored from the bridge. Design calculations showing the damping effect shall be provided to the Owner for review.
Bottom Plugs, Sea Chests, Bilge Wells, Water Jet Intake
All double bottom and wing tanks including the skeg shall have 40mm dia screw fitting, stainless steel docking plugs fitted at their lowest point as far as practicable.
Sea Chest
Two (2) sea chests, one high and one low shall be provided in each engine room. All sea chests shall be provided with hinged stainless steel strainer plate and equipped with valves with air vent, compressed air blow down and chemical dosing.
One sea chest away from main sea chest and sewage discharge for Fresh Water maker water intake shall be provided.
Additionally, one sea chest shall be provided for emergency fire pump.
Locations of sea chests shall be shown in the General Arrangement drawing.
Two sea chest fitted with valves and grating for external fire fighting pumps (FiFi) shall be fitted for future installation.
Marine Growth Prevention System using CU & Al anodes shall be provided in the main sea chests for anti-fouling of seawater lines. Stainless steel ball valves shall be fitted to allow chemical cleaning.
Fender & Bilge Keel
Fenders shall be provided on each side of vessel and at the stern according to fender arrangement drawing.
Bilge keel on each side shall be welded to a doubling plate.
Funnels
Funnels uptake made of 6mm plate with 75 x 50 x 6 O.A stiffeners shall be arranged as shown in the General Arrangement Plan to accommodate the exhausts. Funnels shall serve as engine room hot air exhausts.
Funnels shall be equipped with platforms and ladders to facilitate inspection. Funnel top shall have drain with valve for selection of drain overboard or to dirty oil tank.
Funnel shall have griddles on the side (or aft) for the air out. Doors shall be provided to access funnel from wheelhouse top.
SUPERSTRUCTURE
The front of deckhouse shall be minimum 8mm plate with suitable stiffeners. The sides and top shall be plate with stiffeners. The aft end bulkhead shall be plate with vertical stiffeners.
Deck house shall be designed to take the live loads plus helideck reaction loading.
Clear height throughout accommodation areas, in public areas, corridors and cabins shall be not less than 2250mm.
Helideck
A Helideck shall be provided, forward, partly on top of the accommodation block, suitable for operations with Sikorsky S92, S61-N and Super Puma type of helicopters. The deck shall be arranged at the forward side of the vessel supported by a suitable structure.
The Helideck shall be designed, fabricated and marked in accordance with Class and relevant Civil Aviation Authority rules (CAP 437) including all aspects of fire protection and ground-to-air communication. The Helideck shall not have refueling capability, but arrangements must be made for easy retro fitting of such capability. The deck shall be of welded Aluminium construction of stiffened plate. The supporting structure shall be of lattice type with foundations integrated in the accommodation deckhouse.
The Helideck shall have a non-slip painted surface, a landing net, markings in contrasting colours, beacons, flood lights and wind sock, all in accordance with the requirement of the Regulatory Bodies.
Two ways of escape shall be provided as far apart as possible within the present configuration of the helideck.
The helideck shall be surrounded by a drain gutter and a safety net of 1.50m in width. The gutter shall be fitted with adequate drain points, connected to drain pipes, which shall be extended to the level below the forecastle deck, and shall not pass through accommodation or any part of hull compartments.
The Helideck shall have recessed tie-down points for the helicopter. The recessed tie-down points shall be connected to the drain pipes.
At the Helideck edges, surface type eye lugs shall be provided for the Helideck net.
One (1) set of rescue equipment for Helideck shall be provided in a fiberglass box.
Fire Fighting System
A fire fighting pump, specified in the appropriate section of this specification;
Two (2) foam proportioners (eductors) with a capacity based on the requirements for the subject area;
Two (2) foam concentrate tanks with sufficient capacity according to the relevant Authority and Class.
Two (2) trolley mounted 22kg CO2 extinguisher with an extended applicator and two (2) 50 kg wheeled dry power extinguishers located at each main access to the Helideck shall be supplied.
Helicopter monitoring
The following monitoring equipment shall be installed:
One (1) Helicopter deck monitoring system;
One (1) Helicopter beacon system, including Helibeacon transceiver, power supply unit and on/off switching unit;
One (1) Antenna for Helibeacon system; and
Helicopter landing aids according to rules and regulations shall be fitted to support helicopter operations.
Passenger Lift
One (1) electrical control passenger lift suitable for 15 pax capacity shall be installed between main deck level & ‘F’ deck level.
Lift alarm bell shall be provided in Aft Control Room and Galley.
MAIN MACHINERY, PROPULSION AND STEERING
All machinery shall be of marine type. Machinery and equipment shall be standard design to the extent possible in order to facilitate maintenance and reduce spare parts inventory. The system and layout shall be arranged for safe operation, easy access and minimum mechanical handling.
All generators shall be rated for continuous maximum output under the environmental conditions as specified earlier.
Each main engine set shall form an independent unit including all required accessories to make the engine support systems complete and operational.
Machinery and equipment shall be installed on solid foundation to minimize the effect of vibration, deflection in the crankshafts and couplings and misalignment etc.
Gensets shall be delivered complete with generator and engine on bed. No alignment for sets shall be done onboard. Gensets foundation shall be installed on rubber dampers.
All machinery systems and components shall be of first class marine type. Piping system shall meet the requirements of the classification society unless higher requirements are explicitly stated in this specification. The remote control systems shall be designed and installed as per DP3 requirements for redundancy.
Sensors
All temperature sensors shall be installed in pockets of suitable material. Connections shall be arranged so that they are suitable to be drawn-out for testing purposes.
All level switches shall have test level handle for function test of switch.
All sensors shall be installed in places where it is a minimum risk for damage during normal overhaul and maintenance.
Shut off and test valves with standard connection shall be fitted for all pressure regulating and measuring units as well as for local instruments.
The sensors’ connections to consoles etc. shall be arranged for easy earth fault and cable fault location on the sensor side, i.e. separate wiring between each sensor and the alarm central or other terminating equipment shall be required.
Sensors and instruments shall be mounted in such way that shock and vibrations of the sensor body with connections are avoided.
Pressure sensors exposed to shocks and large vibrations in their working medium shall be protected by damping chambers.
Water pockets shall be avoided in the pressure sensor pipe connections.
All level switches in tanks shall have test level for function test of switch.
Test equipment for temperature and pressure shall be suitable for connection to the respective sensor types.
Bridge Consoles
Bridge shall be split into Fwd and Aft Control rooms to comply with DP3 regulations. There shall be installed two (2) manoeuvre consoles, one (1) forward and one(1) aft.
Forward Control Room
Fwd bridge consoles shall have control and monitoring equipment for propulsion (thrusters), navigation equipment, VHF, wipers, alarm panels, communication systems, back-up DP System, etc.
Aft Control Room
Aft bridge consoles shall have control and monitoring for propulsion (thrusters), Main DP System, navigation equipment, VHF, wipers, alarm panels, communication systems, 8-Point Mooring winches and cargo systems. Following equipment shall be separately installed in Control Rooms:
Engine Control Room
A control room with manoeuvring stand, control for cargo pumps, alarm panel and main switchboard shall be arranged. The control room shall be air conditioned and insulated against noise and heat.
The Engine control room console shall have control and monitoring systems for Engines, electric system in accordance with supplier’s delivery and required by the Classification Society. The console shall have monitoring systems for thrusters, in accordance with supplier’s delivery and required by the Classification Society.
Operator station in engine control room
Two (2) monitoring units shall be installed. These units shall include one (1) colour monitor, one (1) keyboard, one (1) pointing device, one (1) colour printer, one (1) alarm printer and an alarm buzzer.
Watch and responsibility system shall be combined into the common machinery alarm and monitoring system, according to class requirements.
System configuration
Tank group picture
GENERATOR ENGINES
Main Diesel Generators (comply with DPS-3)
The main generators shall be driven by medium speed marine diesels and having the following:
Main engines and motor shall be resilience mounted on skid. The main engine speed governors of electronic type, shall be fitted with necessary control and safety equipment. The governor also shall be arranged for keeping constant speed of engine irrespective of load, in order to keep the voltage and frequency within limits required by class.
The engines shall be air-started and heat exchanger cooled. Engines must be fitted with oil mist as per Class Rules/SOLAS (2250KW and above)
Spare parts shall be supplied according to class requirements for unrestricted service.
The diesel generator set shall be started and stopped from the engine side. The diesel generator set shall be started and connected automatically.
Diesel generators shall be started and stopped remotely from IAS(PMS) with possibility for local start// stop and with manual synchronizing at MSB.
The diesel generator shall automatically shut down in accordance with the manufacturer’s design criteria. A shut-down condition shall be identified by an alarm connected to the IAS. To ensure remote and automatic start, an electric driven LO priming pump shall be provided on the engine. L.O priming pump shall be suppressed during B.O Start.
THRUSTER
The control systems shall be designed according to Class notation requirement. The system shall be a computerized propulsion and maneuvering system which covers the control of the all electric motor driven azimuth thrusters.
A redundant Thruster Control System shall be fitted.
The control systems shall also include 360deg steering possibilities for all azimuth thrusters.
The system shall be interfaced with the Power Management System and frequency drives for all azimuth thrusters for power and RPM control of the propellers.
Separate systems for emergency control of main propellers shall be installed on aft control room and in the engine control room.
The systems shall also be arranged with all necessary I/O units to provide an interface to the DP system, Joystick system, Power Management System and Vessel Automation System.
Necessary instrumentation shall be provided at the motor/starter/frequency drive side to support local maneuvering.
Azimuth and Tunnel Thrusters (comply with DPS-3)
The thrusters shall be driven by 690V / 3 / 60 Hz AC motors. The motor shall be horizontally or vertically mounted. The motor shall be rated to match the thruster output. The input power for each thruster shall be 1800 kW. Frequency Convertors shall be provided for motors.
All thrusters shall be fixed pitch propeller. Controls for main motors shall be from the thruster Vendor.
Circuit breakers for frequency drives for Azimuth Thrusters
Motor operated air circuit breakers for frequency drives for thrusters shall be equipped with an auxiliary contact for feedback signal to the converter (open/closed signal). The circuit breaker shall be part of the frequency drive’s safety system.
The operation of the circuit breakers shall be performed from the actual frequency drive only. The connection of the breaker shall be done by start of the drive.
If there is no voltage to the frequency drive, the pre-charging unit shall first charge the frequency drive and when it is charged, the circuit breaker shall connect. Disconnection of the breaker shall be performed from the actual frequency drive, or manually from the switchboard front.
The motor operated air circuit breaker shall be provided with over current protection, short circuit protection and under-voltage release. Emergency stop switches for converters shall be fitted in manoeuvring panels on the bridge.
MACHINERY CONTROL AND ALARM
One (1) Machinery alarm and monitoring system shall be installed to provide control, monitoring and alarm of all functions necessary for the safe and efficient operation of the main and auxiliary machinery.
The system shall be installed with two (2) work stations in ECR and one(1) work station on the bridge. The various alarms shall be arranged in two (2) separate groups for each main engine and it’s auxiliaries. Earth fault detection with alarm shall be included. The machinery alarm and monitoring system itself and the installation shall comply the requirements for DP 3 Vessels of the listed classification society. All alarms related to the main machinery shall be analogous when relevant. Instruments, sensors and control equipment shall be of simple, robust and standardized design.
Remote transmitters shall be used in order to avoid sensing lines carrying fuel, oil, steam or water being led into the control room.
Local instrumentation, such as thermometers, pressure gauges, etc. shall be provided as necessary for manual start up, control, and monitoring of equipment in the machinery spaces. Scale engraving shall be in metric units.
Pressure and temperature sensors shall be installed in places where there is minimal risk for damage during normal overhaul and maintenance. Temperature sensors shall be installed in wells and be capable of being withdrawn for replacement or calibration. All components and wires shall be marked with numbers in accordance with the instrumentation list and installation drawings.
The main generators engines shall stop automatically with alarm under the following conditions:
Control for Other Machinery Components
Remote manual control of pumps
The following pumps shall be capable of being manually started and stopped from ECR
The following systems shall be controlled from local (equipment supplied) systems:
ELECTRICAL SYSTEM
Electrical load analysis
A preliminary electrical load balance shall be worked out to indicate the load at the following conditions:
DP3 Station Keeping
8-point Moored with Crane and Gangway in use Plus Cargo Operations
Final decision of generator and transformer capacities shall be in accordance with the approved load analysis.
Short Circuit and Device Evaluation Study
A short circuit study shall be performed by the switchboard maker to determine the maximum symmetrical and asymmetrical fault levels developed in the electrical AC system. Protective device evaluation analysis shall also be performed by the switchboard maker, which shall compare the making and breaking ratings of the protective devices (fuses, breakers, etc.) to the available fault duties determined shall be available at their location by the short circuit study.
This evaluation shall determine if the system protective devices can withstand the available short circuit duties that the system can deliver. If problem areas are revealed, recommendations shall be made to correct system deficiencies. The study shall be based upon the one-line diagrams provided for the electrical system.
Bus, distribution board and branch number identifications shall be assigned to the system for easy reference. Faults shall be simulated starting from the generator bus including the 440-volt buses, 220V buses and AC distribution boards.
Battery Sizing Calculation
A battery sizing study shall be performed to determine the required minimum capacity for the various 24VDC battery systems mention above. The study shall also include recommended battery charger capacity.
Illumination Intensity Study
An Illumination Intensity calculation shall be performed, to verify the required quantity of Light fillings and Floodlights. One Illumination Intensity calculation shall be performed for accommodation/machinery /Internal rooms (typical rooms) and one calculation shall be performed for open decks.
Electrical power system
The ship shall have alternating current system, 3 phases, 60 Hz with insulated neutral as a main system.
The ships electrical power sources shall be:
One (1) Emergency/harbour generator, approx. 450 kW, 450V, 3-phase, 60 Hz, 3- wire
Five (5) main propulsion generators, approx 3 x 2500 kW, 690V, 3-phase, 60 Hz, 3-wire and 2 x 3750 kW, 690V, 3-phase, 60 Hz, 3-wire Harmonic distortion on 690V bus shall be below recommended from class, but maximum 5% THD and less than 3% for any single harmonic
Vessel should have AFE Frequency converters or equivalent for Azimuth Thrusters and tunnel thrusters.
.
ELECTRICAL SUPPLY SYSTEMS
The electrical plant shall be powered by five (5) main generators or by the Emergency/harbour generator, or by the shore connection. The electrical AC installation shall be based on a 3-phase, insulated 3 wire system.
Generating sets shall consist of:
Main Distribution systems
The 440V AC Ship Service system shall be supplied from the 690V Ship Service switchboard via appropriate (690V/450V AC) transformers. The 440V AC systems shall serve all galley and laundry equipment and other 440V AC power consumers.
220V AC Ship Service System
The 220V AC Ship Service system shall be supplied from the 440V Ship Service switchboard via appropriate (450V/230V AC) transformers. The 220V AC systems shall serve all lighting circuits, domestic equipment and other 220V AC power consumers.
440V AC Emergency System
the emergency generator shall be automatically started and shall open the bus tie breakers to the 440VAC Ship Service switchboard. Then the emergency generator breaker shall be engaged and supply power to the emergency consumers. The emergency generator circuit breaker shall be electrically interlocked in order to prevent damage to electrical systems.
This technical specification document along with General Arrangement Plan shall describe the characteristics and design intended vessel design.
The vessel shall be outfitted with machinery and provided with equipment according to the latest rules and regulation of the Classification Society for worldwide service and operation. The designed vessel shall also comply with all statutory regulations laid down by the Flag Administration and IMO for such vessels for worldwide operation and suitable service in connection with offshore installations or worlwide transit.
Basic requirement of the vessel shall be defined before design starts
- Deadweight or cargo carrying capacity
- Size of Accommodation
- Speed and Endurance requirement
- Storage and handling facility
- Consumable ( FW/FO) requirement
- Crane installation requirement
- Propulsion system design
- specific requirement for offshore operation i.e ROV, Diving;
Deck layout shall be suitable for intended operation and cargo holds shall be sufficient for intended cargo carrying.
Ship Design Spiral
Stability
The Vessel shall meet the following codes with respect to stability:
- International Loadline Convention, 1966
- Bow height
- Convention on the International Regulations for Preventing Collision at sea (COLREG) 1972 and Amendments including that of 1981;
- Rules of Classification Society;
- IMO Resolution 2008 SPS Code carrying special persons
- SOLAS 1997 with amendments.
Propulsion system Selection
Propeller sizing
Dynamic Positioning System
These requirement are defend as per DP-3 requirement for easy comprehension. DP-1,DP-2 system shall be configured based on the redundancy philosphy.
The design and philosophy of the DP system shall be developed along with the chosen equipment vendor and shall comply with Classification Society regulations. When designing and detailing the system best industry practices and IMCA recommendations shall be taken into account.
The vessel shall hold position in any of the loading conditions and under the following environmental conditions:
- Water Depth
- Water Current speed
- Significant Wave Height
- Wind Speed
The fully operational Dual Redundant DP system shall keep the vessel in position and system accuracy. The DPS shall comprise of:
- DP control consoles;
- DP controllers;
- Gyrocompass;
- Anemometers;
- Reference units as per class requirements;
- Uninterruptible power supply units; and
- DP data logger.
The DPS reference systems shall typically comprise of the following
- Two (2) units of DGPS;
- One hydro acoustic positioning unit including a hull mounted gate valve and weldable flange;
- One unit of Lightweight Taut Wire system
- Two relative position reference systems;
- 3 Motion Ref Units (at least one with Roll, Pitch & Heave sensor).
DP system shall interface with the following:
- Azimuth thrusters;
- Tunnel thrusters;
- Propulsion thrusters
- Main switchboards (power status and alarms); and
- DPS reference systems.
In addition to the basic DPS functions, the following shall be provided:
- Auto Station keeping;
- Standby and Training;
- Mixed manual auto mode with joystick lever;
- Auto heading;
- Power monitoring and black out protection;
- Quick current update function;
- Draft compensation;
- Fuel saving mode;
- Natural GPS operation;
- Manual mode with joystick;
- Reference system to facilitate parameter change by crew;
- DP capability and consequence analysis;
- Track follow mode;
- Follow Target;
- Auto Track High and Low speed;
- Auto Pilot; and
- Alternative Rotation Points.
The system shall include online consequence analysis, online DP capability analysis, motion prediction analysis and DP operation output alarm. Hydro-acoustic positioning unit and sea valve open / close indication shall be available locally as well as in the operation station. The valve shall be gear operated . The valve shall have interlock with the pole up / down controls. As the vessel shall be DPS-3 Classed, an Independent Joystick System (IJS) shall be supplied in addition to the DPS system. Provision shall be made for attaching the independent Joystick in Both Fwd and Aft Control rooms and P/S wings.
Noise and vibration
Suppression of noise shall be given full consideration at the design stage, the final levels of both air and structure borne interference being sufficiently low as to not cause any reduction in specified part performance of any installation equipment.
Bulkheads in accommodation shall give minimum 40dB sound reduction from cabin to cabin and 35dB sound reduction bulkheads in other spaces. Special precautions shall be made for ceiling fastening to avoid noise and vibration. Combustion machinery and hydraulic aggregates shall be installed on flexible mounting joints and shall have flexible pipe connections.
Vibration Levels Reference - ISO 6954 - Guidance notes on acceptable vibration levels and their measurement shall be followed.
The ship shall have sufficient positive stability in all normal conditions of loading and shall comply with the standards as recommended by Regulatory Bodies. The builder shall carry out an inclining experiment in the presence of the Classification Society and authorities, as required. The results of the inclining experiment shall be used in the preparation of Final Trim and Stability Book for the use of ship’s officers. The stability data shall include loading conditions sufficient to cover all normal operating roles. The builder shall submit the completed Trim and Stability Book to the Classification Society and authorities and obtain approval. For more than one vessel of the same class, the inclining experiment shall be carried out for the first vessel only subject to classification and authority approvals. However, a draft survey shall be carried out on subsequent vessels.
HULL AND SUPERSTRUCTURE
The vessel shall be of all welded construction in accordance with contract plans, specifications, and Class Society rules. Hull structure shall meet Classification Society requirements and all steel plate shall be Classification Society certified and stamped.
The steel hull and deck erections shall be of all welded construction.
Longitudinal framing system for bottom, sideshell and decks with deep transverse frames spaced at 1.8m shall be adopted. Scantlings shall be according to the Classification Society requirement for thickness of plate and modulus of sections.
All steel plates, sections, hull-forging and castings shall meet Classification Society requirements and shall be supplied with test certificates where applicable. All smith-work of fabricated fittings shall be of neat design, strong, smooth and free from defects.
Shell Plating and Bottom Structure
The bottom (including bilge strake) and side plating shall be longitudinally plated, shall have welded butts and seams and except in way of openings for sea water inlets, thrusters well, hawse pipes and forefoot, etc. where heavy plates shall be fitted.
Double bottom shall be provided except forepeak and stern propulsion room and in way of deep tank. Inner Bottom shall be stiffened with vent holes throughout to ensure proper drainage and to eliminate entrapment of air pockets. Double bottom where fitted shall have a height of 1800mm
A flat plate keel shall be fitted throughout the bottom of the vessel.
Main Deck
The main deck shall not have sheer and camber. The main deck shall be longitudinally framed and supported by deck girders and deep transverses. The deck plating aft of the superstructure FR 29 to AP shall take uniformly distributed load of 15 tonnes/m2, forward of FR 29 outside of superstructure shall be designed for 5t/m2.
Elsewhere the deck plating shall be according to Classification Society requirements. The deck plating shall be welded direct to the shell. Extra thick insert plates shall be fitted at deck machinery areas, winches, capstans, tugger winch, bollards, fwd and aft, and at anchor pockets.
Watertight Bulkheads
The vessel shall be subdivided by longitudinal and transverse watertight bulkheads as shown in the General Arrangement drawing. Vertical Zones as per SOLAS shall be maintained.
Tanks
Tanks shall be suitable for their intended use. All tanks shall be easily accessible through adequate size and number of manholes. All tanks shall be fitted with ladders or hand grips.
Moonpool
One (1) Moonpool of 7000 x 7000 mm (approx) square clear opening equipped with water column dampening arrangement shall be provided for the launch and recovery of the saturated diving bell and other subsea equipment. The moon pool shall be of an aerated type.
Skeg
A box shape skeg shall be fitted at fore & aft. The bottom of the skeg shall be 15mm, sides and webs shall be 12mm or as required.
Roll Stabilizing Tank (flume tank)
Two (2) anti-roll tank of passive type shall be provided. The tanks shall carry sea water for dampening the roll. The tanks shall be built with a high degree of flexibility and shall be capable of controlling the roll of the vessel for variety of displacement and roll periods.
The roll dampening system shall have an interface with the vessels computerized stability program and shall be able to be continuously monitored from the bridge. Design calculations showing the damping effect shall be provided to the Owner for review.
Bottom Plugs, Sea Chests, Bilge Wells, Water Jet Intake
All double bottom and wing tanks including the skeg shall have 40mm dia screw fitting, stainless steel docking plugs fitted at their lowest point as far as practicable.
Sea Chest
Two (2) sea chests, one high and one low shall be provided in each engine room. All sea chests shall be provided with hinged stainless steel strainer plate and equipped with valves with air vent, compressed air blow down and chemical dosing.
One sea chest away from main sea chest and sewage discharge for Fresh Water maker water intake shall be provided.
Additionally, one sea chest shall be provided for emergency fire pump.
Locations of sea chests shall be shown in the General Arrangement drawing.
Two sea chest fitted with valves and grating for external fire fighting pumps (FiFi) shall be fitted for future installation.
Marine Growth Prevention System using CU & Al anodes shall be provided in the main sea chests for anti-fouling of seawater lines. Stainless steel ball valves shall be fitted to allow chemical cleaning.
Fender & Bilge Keel
Fenders shall be provided on each side of vessel and at the stern according to fender arrangement drawing.
Bilge keel on each side shall be welded to a doubling plate.
Funnels
Funnels uptake made of 6mm plate with 75 x 50 x 6 O.A stiffeners shall be arranged as shown in the General Arrangement Plan to accommodate the exhausts. Funnels shall serve as engine room hot air exhausts.
Funnels shall be equipped with platforms and ladders to facilitate inspection. Funnel top shall have drain with valve for selection of drain overboard or to dirty oil tank.
Funnel shall have griddles on the side (or aft) for the air out. Doors shall be provided to access funnel from wheelhouse top.
SUPERSTRUCTURE
The front of deckhouse shall be minimum 8mm plate with suitable stiffeners. The sides and top shall be plate with stiffeners. The aft end bulkhead shall be plate with vertical stiffeners.
Deck house shall be designed to take the live loads plus helideck reaction loading.
Clear height throughout accommodation areas, in public areas, corridors and cabins shall be not less than 2250mm.
Helideck
A Helideck shall be provided, forward, partly on top of the accommodation block, suitable for operations with Sikorsky S92, S61-N and Super Puma type of helicopters. The deck shall be arranged at the forward side of the vessel supported by a suitable structure.
The Helideck shall be designed, fabricated and marked in accordance with Class and relevant Civil Aviation Authority rules (CAP 437) including all aspects of fire protection and ground-to-air communication. The Helideck shall not have refueling capability, but arrangements must be made for easy retro fitting of such capability. The deck shall be of welded Aluminium construction of stiffened plate. The supporting structure shall be of lattice type with foundations integrated in the accommodation deckhouse.
The Helideck shall have a non-slip painted surface, a landing net, markings in contrasting colours, beacons, flood lights and wind sock, all in accordance with the requirement of the Regulatory Bodies.
Two ways of escape shall be provided as far apart as possible within the present configuration of the helideck.
The helideck shall be surrounded by a drain gutter and a safety net of 1.50m in width. The gutter shall be fitted with adequate drain points, connected to drain pipes, which shall be extended to the level below the forecastle deck, and shall not pass through accommodation or any part of hull compartments.
The Helideck shall have recessed tie-down points for the helicopter. The recessed tie-down points shall be connected to the drain pipes.
At the Helideck edges, surface type eye lugs shall be provided for the Helideck net.
One (1) set of rescue equipment for Helideck shall be provided in a fiberglass box.
Fire Fighting System
A fire fighting pump, specified in the appropriate section of this specification;
Two (2) foam proportioners (eductors) with a capacity based on the requirements for the subject area;
Two (2) foam concentrate tanks with sufficient capacity according to the relevant Authority and Class.
Two (2) trolley mounted 22kg CO2 extinguisher with an extended applicator and two (2) 50 kg wheeled dry power extinguishers located at each main access to the Helideck shall be supplied.
Helicopter monitoring
The following monitoring equipment shall be installed:
One (1) Helicopter deck monitoring system;
One (1) Helicopter beacon system, including Helibeacon transceiver, power supply unit and on/off switching unit;
One (1) Antenna for Helibeacon system; and
Helicopter landing aids according to rules and regulations shall be fitted to support helicopter operations.
Passenger Lift
One (1) electrical control passenger lift suitable for 15 pax capacity shall be installed between main deck level & ‘F’ deck level.
Lift alarm bell shall be provided in Aft Control Room and Galley.
MAIN MACHINERY, PROPULSION AND STEERING
All machinery shall be of marine type. Machinery and equipment shall be standard design to the extent possible in order to facilitate maintenance and reduce spare parts inventory. The system and layout shall be arranged for safe operation, easy access and minimum mechanical handling.
All generators shall be rated for continuous maximum output under the environmental conditions as specified earlier.
Each main engine set shall form an independent unit including all required accessories to make the engine support systems complete and operational.
Machinery and equipment shall be installed on solid foundation to minimize the effect of vibration, deflection in the crankshafts and couplings and misalignment etc.
Gensets shall be delivered complete with generator and engine on bed. No alignment for sets shall be done onboard. Gensets foundation shall be installed on rubber dampers.
All machinery systems and components shall be of first class marine type. Piping system shall meet the requirements of the classification society unless higher requirements are explicitly stated in this specification. The remote control systems shall be designed and installed as per DP3 requirements for redundancy.
Sensors
All temperature sensors shall be installed in pockets of suitable material. Connections shall be arranged so that they are suitable to be drawn-out for testing purposes.
All level switches shall have test level handle for function test of switch.
All sensors shall be installed in places where it is a minimum risk for damage during normal overhaul and maintenance.
Shut off and test valves with standard connection shall be fitted for all pressure regulating and measuring units as well as for local instruments.
The sensors’ connections to consoles etc. shall be arranged for easy earth fault and cable fault location on the sensor side, i.e. separate wiring between each sensor and the alarm central or other terminating equipment shall be required.
Sensors and instruments shall be mounted in such way that shock and vibrations of the sensor body with connections are avoided.
Pressure sensors exposed to shocks and large vibrations in their working medium shall be protected by damping chambers.
Water pockets shall be avoided in the pressure sensor pipe connections.
All level switches in tanks shall have test level for function test of switch.
Test equipment for temperature and pressure shall be suitable for connection to the respective sensor types.
Bridge Consoles
Bridge shall be split into Fwd and Aft Control rooms to comply with DP3 regulations. There shall be installed two (2) manoeuvre consoles, one (1) forward and one(1) aft.
Forward Control Room
Fwd bridge consoles shall have control and monitoring equipment for propulsion (thrusters), navigation equipment, VHF, wipers, alarm panels, communication systems, back-up DP System, etc.
Aft Control Room
Aft bridge consoles shall have control and monitoring for propulsion (thrusters), Main DP System, navigation equipment, VHF, wipers, alarm panels, communication systems, 8-Point Mooring winches and cargo systems. Following equipment shall be separately installed in Control Rooms:
- Fire alarm panel & Gas Detection panel.
- Navigation lights (main /emergency)
- Signal lights
- Distribution panels
- Emergency stop system of aux.
- Panel for watertight doors
- Emergency stop with running lights for cargo pumps
- Hospital alarm (also outside the hospital)
- CCTV Controls and monitoring.
- Operator station in wheelhouse (Aft Control Room)
- One (1) monitoring unit shall be installed in Aft Control room. This unit shall include one (1) colour monitor, one (1) PC with keyboard, one (1) pointing device and an alarm buzzer.
Engine Control Room
A control room with manoeuvring stand, control for cargo pumps, alarm panel and main switchboard shall be arranged. The control room shall be air conditioned and insulated against noise and heat.
The Engine control room console shall have control and monitoring systems for Engines, electric system in accordance with supplier’s delivery and required by the Classification Society. The console shall have monitoring systems for thrusters, in accordance with supplier’s delivery and required by the Classification Society.
Operator station in engine control room
Two (2) monitoring units shall be installed. These units shall include one (1) colour monitor, one (1) keyboard, one (1) pointing device, one (1) colour printer, one (1) alarm printer and an alarm buzzer.
Watch and responsibility system shall be combined into the common machinery alarm and monitoring system, according to class requirements.
System configuration
Tank group picture
GENERATOR ENGINES
Main Diesel Generators (comply with DPS-3)
The main generators shall be driven by medium speed marine diesels and having the following:
- Rating : 6 x 2500 kW (three (3) in each engine room)
- Voltage : 690V, 3-phase, 60 Hz
- Speed : 600 - 900 rpm
- Fuel : MDO
Main engines and motor shall be resilience mounted on skid. The main engine speed governors of electronic type, shall be fitted with necessary control and safety equipment. The governor also shall be arranged for keeping constant speed of engine irrespective of load, in order to keep the voltage and frequency within limits required by class.
The engines shall be air-started and heat exchanger cooled. Engines must be fitted with oil mist as per Class Rules/SOLAS (2250KW and above)
Spare parts shall be supplied according to class requirements for unrestricted service.
The diesel generator set shall be started and stopped from the engine side. The diesel generator set shall be started and connected automatically.
Diesel generators shall be started and stopped remotely from IAS(PMS) with possibility for local start// stop and with manual synchronizing at MSB.
The diesel generator shall automatically shut down in accordance with the manufacturer’s design criteria. A shut-down condition shall be identified by an alarm connected to the IAS. To ensure remote and automatic start, an electric driven LO priming pump shall be provided on the engine. L.O priming pump shall be suppressed during B.O Start.
THRUSTER
The control systems shall be designed according to Class notation requirement. The system shall be a computerized propulsion and maneuvering system which covers the control of the all electric motor driven azimuth thrusters.
A redundant Thruster Control System shall be fitted.
The control systems shall also include 360deg steering possibilities for all azimuth thrusters.
The system shall be interfaced with the Power Management System and frequency drives for all azimuth thrusters for power and RPM control of the propellers.
Separate systems for emergency control of main propellers shall be installed on aft control room and in the engine control room.
The systems shall also be arranged with all necessary I/O units to provide an interface to the DP system, Joystick system, Power Management System and Vessel Automation System.
Necessary instrumentation shall be provided at the motor/starter/frequency drive side to support local maneuvering.
Azimuth and Tunnel Thrusters (comply with DPS-3)
The thrusters shall be driven by 690V / 3 / 60 Hz AC motors. The motor shall be horizontally or vertically mounted. The motor shall be rated to match the thruster output. The input power for each thruster shall be 1800 kW. Frequency Convertors shall be provided for motors.
All thrusters shall be fixed pitch propeller. Controls for main motors shall be from the thruster Vendor.
Circuit breakers for frequency drives for Azimuth Thrusters
Motor operated air circuit breakers for frequency drives for thrusters shall be equipped with an auxiliary contact for feedback signal to the converter (open/closed signal). The circuit breaker shall be part of the frequency drive’s safety system.
The operation of the circuit breakers shall be performed from the actual frequency drive only. The connection of the breaker shall be done by start of the drive.
If there is no voltage to the frequency drive, the pre-charging unit shall first charge the frequency drive and when it is charged, the circuit breaker shall connect. Disconnection of the breaker shall be performed from the actual frequency drive, or manually from the switchboard front.
The motor operated air circuit breaker shall be provided with over current protection, short circuit protection and under-voltage release. Emergency stop switches for converters shall be fitted in manoeuvring panels on the bridge.
MACHINERY CONTROL AND ALARM
One (1) Machinery alarm and monitoring system shall be installed to provide control, monitoring and alarm of all functions necessary for the safe and efficient operation of the main and auxiliary machinery.
The system shall be installed with two (2) work stations in ECR and one(1) work station on the bridge. The various alarms shall be arranged in two (2) separate groups for each main engine and it’s auxiliaries. Earth fault detection with alarm shall be included. The machinery alarm and monitoring system itself and the installation shall comply the requirements for DP 3 Vessels of the listed classification society. All alarms related to the main machinery shall be analogous when relevant. Instruments, sensors and control equipment shall be of simple, robust and standardized design.
Remote transmitters shall be used in order to avoid sensing lines carrying fuel, oil, steam or water being led into the control room.
Local instrumentation, such as thermometers, pressure gauges, etc. shall be provided as necessary for manual start up, control, and monitoring of equipment in the machinery spaces. Scale engraving shall be in metric units.
Pressure and temperature sensors shall be installed in places where there is minimal risk for damage during normal overhaul and maintenance. Temperature sensors shall be installed in wells and be capable of being withdrawn for replacement or calibration. All components and wires shall be marked with numbers in accordance with the instrumentation list and installation drawings.
- Engineer’s alarm
- Deadman alarm
- Abandon Ship alarm
- Automatic telephone alarm
- Batteryless telephone alarm
- Fire & General alarm
- Engine alarm
- CO2 Alarm
The main generators engines shall stop automatically with alarm under the following conditions:
- Engine low lub. oil pressure
- Engine high coolant temperature
- Engine over speed
- Engine high bearing temp (if recommended by supplier)
- Engine oil mist detection (if applicable) yes is applicable
- Manual emergency stop button shall be provided in the ECR and aft control station.
Control for Other Machinery Components
Remote manual control of pumps
The following pumps shall be capable of being manually started and stopped from ECR
- Bilge and Ballast Pumps
- Main DO Supply Pumps
- Diesel Oil Transfer Pumps.
- Fresh Water Cooling Pumps
- M.E. Jacket Water Pumps
- Main Sea Water Pumps
- Local manual control of equipment
The following systems shall be controlled from local (equipment supplied) systems:
- Hydrophore plant
- Air condition and ventilation
- Sewage plant
- Starting air system
- Lub oil system
- Fuel oil and lub oil purifiers
- Fresh water filling
- Cables/ Leads & Piping for Machinery Control Systems (DPS-3)
ELECTRICAL SYSTEM
Electrical load analysis
A preliminary electrical load balance shall be worked out to indicate the load at the following conditions:
- Transit - In Field
- Stand-by
- Cargo load - discharge & Crane/Telescopic Gangway in use (DP3)
- Cargo load/discharge(harbour)
- Harbour manoeuvring
- Harbour resting
- Emergency power
DP3 Station Keeping
8-point Moored with Crane and Gangway in use Plus Cargo Operations
Final decision of generator and transformer capacities shall be in accordance with the approved load analysis.
Short Circuit and Device Evaluation Study
A short circuit study shall be performed by the switchboard maker to determine the maximum symmetrical and asymmetrical fault levels developed in the electrical AC system. Protective device evaluation analysis shall also be performed by the switchboard maker, which shall compare the making and breaking ratings of the protective devices (fuses, breakers, etc.) to the available fault duties determined shall be available at their location by the short circuit study.
This evaluation shall determine if the system protective devices can withstand the available short circuit duties that the system can deliver. If problem areas are revealed, recommendations shall be made to correct system deficiencies. The study shall be based upon the one-line diagrams provided for the electrical system.
Bus, distribution board and branch number identifications shall be assigned to the system for easy reference. Faults shall be simulated starting from the generator bus including the 440-volt buses, 220V buses and AC distribution boards.
Battery Sizing Calculation
A battery sizing study shall be performed to determine the required minimum capacity for the various 24VDC battery systems mention above. The study shall also include recommended battery charger capacity.
Illumination Intensity Study
An Illumination Intensity calculation shall be performed, to verify the required quantity of Light fillings and Floodlights. One Illumination Intensity calculation shall be performed for accommodation/machinery /Internal rooms (typical rooms) and one calculation shall be performed for open decks.
Electrical power system
The ship shall have alternating current system, 3 phases, 60 Hz with insulated neutral as a main system.
- Main generators, 690V, 3-phase, 60 Hz
- Emergency/Harbour generator, 450V, 3-phase, 60 Hz
- Transformers 440/220V and 690/450V
- Electrical motors in general, 440V, 3-phase, 60 Hz
- Electrical heaters, 440V and 220 Volts
- Heavy galley -and laundry machinery, 440V and 220 Volts 220V AC - Illumination, receptacles - Minor
- heaters
- Minor electrical motors (below 1 kW) – Galley and laundry equipment
- Remote control equipment
- Control voltage
- Rectifiers/battery chargers
- Electronic equipment
- Communication systems 24V DC - Electronic equipment (navigational monitoring, governors etc.) -
- Remote control
- Starting battery for emergency diesel engine. All One (1) phase consumers shall be distributed as equally as possible on the three (3) phases.
The ships electrical power sources shall be:
One (1) Emergency/harbour generator, approx. 450 kW, 450V, 3-phase, 60 Hz, 3- wire
Five (5) main propulsion generators, approx 3 x 2500 kW, 690V, 3-phase, 60 Hz, 3-wire and 2 x 3750 kW, 690V, 3-phase, 60 Hz, 3-wire Harmonic distortion on 690V bus shall be below recommended from class, but maximum 5% THD and less than 3% for any single harmonic
Vessel should have AFE Frequency converters or equivalent for Azimuth Thrusters and tunnel thrusters.
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ELECTRICAL SUPPLY SYSTEMS
The electrical plant shall be powered by five (5) main generators or by the Emergency/harbour generator, or by the shore connection. The electrical AC installation shall be based on a 3-phase, insulated 3 wire system.
Generating sets shall consist of:
- Main generators: 690VAC, - 60Hz
- Emergency/Harbour generator: 440VAC, - 60Hz
Main Distribution systems
- 690V AC Main System
- 440V AC Ship Service System
The 440V AC Ship Service system shall be supplied from the 690V Ship Service switchboard via appropriate (690V/450V AC) transformers. The 440V AC systems shall serve all galley and laundry equipment and other 440V AC power consumers.
220V AC Ship Service System
The 220V AC Ship Service system shall be supplied from the 440V Ship Service switchboard via appropriate (450V/230V AC) transformers. The 220V AC systems shall serve all lighting circuits, domestic equipment and other 220V AC power consumers.
440V AC Emergency System
the emergency generator shall be automatically started and shall open the bus tie breakers to the 440VAC Ship Service switchboard. Then the emergency generator breaker shall be engaged and supply power to the emergency consumers. The emergency generator circuit breaker shall be electrically interlocked in order to prevent damage to electrical systems.
