DESC:FORM 2

THE PATENTS ACT, 1970

(39 of 1970)

&

THE PATENT RULES, 2003

COMPLETE SPECIFICATION

(See Section 10 and Rule 13)

Title of invention:

AN OFFSHORE VESSEL

Applicant:

Mazagon Dock Shipbuilders Limited
A company Incorporated in India under the Companies Act, 1956
Under Ministry of Defence,
(A Govt. of India Undertaking)
Having address:
Dockyard Road, Mazagon,
Mumbai - 400010, Maharashtra, India

The following specification describes the invention and the manner in which it is to be performed.

CROSS-REFERENCE TO RELATED APPLICATION AND PRIORITY

[001] The present application claims priority from Indian Patent application no. (201821043311) filed on 17th November, 2018.

TECHNICAL FIELD

[002] The present subject matter described herein, in general, relates to shipbuilding. More particularly, the present subject matter further relates to an offshore vessel.

BACKGROUND

[003] Generally, offshore vessels are specially designed ships capable of search and rescue operations, embarkation and operation of helicopters (if required), rescue and surveillance, pollution response against oil spillage and external firefighting. Conventionally, the offshore vessels range from 50 metres to 105 metres and can accommodate different elements or components on board for different missions like search and rescue operations (SAR).

SUMMARY

[004] Before the present offshore vessel, is described, it is to be understood that this application is not limited to the particular systems, and methodologies described, as there can be multiple possible embodiments that are not expressly illustrated in the present disclosures. It is also to be understood that the terminology used in the description is for describing the particular implementations, versions, or embodiments only, and is not intended to limit the scope of the present application. This summary is provided to introduce aspects related to the offshore vessel. This summary is not intended to identify essential features of the claimed subject matter nor is it intended for use in determining or limiting the scope of the claimed subject matter.
[005] In one implementation, an offshore vessel is disclosed. In one embodiment, the offshore vessel comprises a hull, a deck, a plurality of fixed fin stabilizers, a twin funnel exhaust, and a plurality of bulkheads. In another embodiment, the hull has a V cross section at a bow side of the hull and a transom side of the hull. In one another embodiment, the deck is mounted on a top of the hull. The plurality of fixed fin stabilizers are mounted on the bottom shell. In one more embodiment, the twin-funnel exhaust is mounted on the deck. Further, the plurality of bulkheads are located on an inner bottom surface of the hull.
BRIEF DESCRIPTION OF THE DRAWINGS

[006] The foregoing detailed description of embodiments is better understood when read in conjunction with the appended drawings. For the purpose of illustrating of the present subject matter, an example of construction of the present subject matter is provided as figures; however, the invention is not limited to the specific system disclosed in the document and the figures.

[007] The present subject matter is described in detail with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to refer various features of the present subject matter.

[008] Figure 1 illustrates a front view of a hull, in accordance with an embodiment of the present subject matter.

[009] Figure 2 illustrates a side view of an offshore vessel, in accordance with an embodiment of the present subject matter.
DETAILED DESCRIPTION

[0010] Some embodiments of this disclosure, illustrating all its features, will now be discussed in detail. The words “fighting”, “loading”, “accommodating”, “corresponding” and other forms thereof, are intended to be equivalent in meaning and be open ended such that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items. It must also be noted that as used herein and in the appended claims, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Although an offshore vessel, similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present disclosure, is now described. The disclosed embodiments for the offshore vessel is merely example of the disclosure, which may be embodied in various forms.
[0011] Various modifications to the embodiment will be readily apparent to those skilled in the art and the generic principles herein may be applied to other embodiments for the offshore vessel. However, one of ordinary skill in the art will readily recognize that the present disclosure for the offshore vessel is not intended to be limited to the embodiments described, but is to be accorded the widest scope consistent with the principles and features described herein.

[0012] As described above, conventional vessels like frigates and corvettes form a part of the frontline warships, large in size and are of high cost. Further, they are not meant for routine search and rescue operations in seas or oceans, as they are not equipped for broad variety of missions like counter-drug operations, counter-piracy, counter-smuggling operations. Thus there is a need overcome this limitation.

[0013] In one implementation, an offshore vessel is disclosed. In one embodiment, the offshore vessel comprises a hull, a deck, a plurality of fixed fin stabilizers, a twin funnel exhaust, and a plurality of bulkheads. In another embodiment, the hull has a V cross section at a bow side of the hull and a transom side of the hull. In one another embodiment, the deck is mounted on a top of the hull. The plurality of fixed fin stabilizers are mounted to an outer surface on a bottom half of the hull. In one more embodiment, the twin-funnel exhaust is mounted on the deck. Further, the plurality of bulkheads are located on an inner bottom surface of the hull.
[0014] In one embodiment, there may include an advantage, that is, the offshore vessel is a compact structure that is used for multiple operations for e.g. search and rescue and the like.

[0015] Now, referring to Figures 1-2, Figure 1 illustrates a front view 100 of a hull 102. Figure 2 illustrates a side view of an offshore vessel 200. Further, the present subject is explained with reference to Figures 1 to 2, in order to maintain the readability of the present subject matter.
[0016] In one embodiment, the offshore vessel 200 comprises a hull 102, a deck 202, a plurality of fixed fin stabilizers 206, a twin funnel exhaust (not shown), and a plurality of bulkheads 204. In one aspect, the hull 102 has a V cross section at a bow side of the hull 102 and a transom side of the hull 102. In another aspect, the hull 102 has the deck 202. The deck 202 may further comprise a helideck 210, a fixed helicopter hangar 208, one or more fire-fighting equipment (not shown) mounted on the deck 202. The deck may further comprise the twin-funnel exhaust that may be mounted on the deck 202. The deck 202 may be mounted on a top of the hull 102. The plurality of fixed fin stabilizers 206 are mounted to an outer surface on a bottom half of the hull 102. In yet another aspect, the hull 102 comprises the plurality of bulkheads 204. The plurality of bulkheads 204 are located on an inner bottom surface of the hull 102. The hull 102 may comprise a plurality of bow thrusters 212. The plurality of bow thrusters 212 are coupled to the outer surface on the bottom half of the hull 102. Further, the hull 102 may comprise a round bilge. Furthermore, the hull may be welded steel plate and stiffener arrangement designed to Classification Society requirements.
[0017] In subsequent embodiment, principal dimensions of the offshore vessel 200 is described in the table.

Length overall 85.0M
Length waterline 80.0M
Bream waterline 11.5 M
Depth moulded to no 2 deck 5.80 M
Design draft moulded -
Amidships 3.48 M

[0018] In one implementation, all materials used in the construction of the vessel by the Shipbuilders or his sub-contractors is to be of accepted normal marine standard unless specified otherwise. The Shipbuilder is to make available to the Owner any requested details of equipment specified as being of shipbuilders' standard. All items of equipment and outfit to be installed and tested in accordance with the requirements of the Classification Society and to the satisfaction of the Owner's representative where applicable. Workmanship throughout the vessel is to be carried out in accordance with the Shipbuilders' or his subcontractors' normal standards, all being in line with good marine practice.
[0019] In another implementation, the design principals of the offshore vessel 200 is mentioned. The offshore vessel 200 may be mono hull displacement vessel designed to achieve 26 knots speed. The offshore vessel 200 may be sea worthy with the capability to undertake operational missions up to sea state 7 and helicopter operations up to sea state 5. The vessel may have adequate stability under all operating conditions complying with NES 109 standards. The offshore vessel 200 may have a helideck capable of accommodating Advanced light helicopter (ALH) and a fixed helicopter hangar. The offshore vessel 200 may be designed with both gross and net registered tonnages in accordance with latest tonnage regulations. International Gross and Net Tonnage Certificates to be supplied.

[0020] In one another implementation, the hull construction is explained, the materials used in the construction of the offshore vessel 200 by the Shipbuilder or its subcontractors is to be of usual marine standard unless specified otherwise.

[0021] Steel plates, sections, hull forgings and castings to be to Classification requirements and to have maker's name and test marks clearly stamped thereon. Further, Vessel to be of all welded construction in accordance with construction plans, specifications and classification requirements.

[0022] Welding to be both intermittent and continuous as required by classification, using manual, automatic and semi-automatic methods. The main hull 102 to main deck level aft of the engine room to be fully welded before sighting and boring for propeller shafting.

[0023] In one more implementation, the lower portion of the stem to consist of a mild steel round bar efficiently attached to the deck and shell plating. The upper portion extending from about the load waterline to the forecastle bulwark level to be formed of steel plate, scarphed to the stem bar and well rounded towards deck level. The stern to be of flat transom type with radiused corners. Internal structure of the stern to be designed to carry working loads superimposed when vessel is handling heavy items on working deck. Strong girder and transverse floor systems are to be arranged to form rigid foundations for the steering gear seating.

[0024] Shell plating under the stern in way of the propellers to be a minimum of 12mm thick. Further, Keel to be formed from a flat steel plate of rule width and thickness, being properly shaped at the ends of the vessel to take stem bar. A single centreline girder not less than rule height and thickness is to be continuously welded throughout full length of vessel. Where passing through double bottom tanks or deep tanks with centreline divisions, the centre girder is to be of oil / watertight construction. In way of centreline division bulkheads, the girder is to be formed by the lower bulkhead plating.

[0025] In one embodiment, a double bottom is to be arranged in way of both the lower forward spaces and the engine room generally as indicated on the general arrangement plan. The double bottom spaces are to be longitudinally framed with plate floors as required by Classification. Plate floors are to be arranged on every transverse web frame and all floors where depth permits (excluding tanks ends) are to have lightening and access holes, minimum size 600mm x 400mm. Clear of double bottom tanks, transverse plate floors are to be fitted on every main frame in way of the engine rooms, deep tanks, peaks and stern. Floors where depth permits are to have maximum size lightening holes. Floors to be welded to shell, tank top and girder plating.

[0026] Full depth girders to carry the main engines and gearbox seating are to be arranged in the engine rooms. Girders to be of continuous construction.

[0027] Intercostal full depth girders clear of engine seats are to be arranged port and starboard extending forward and aft as shape permits. Outboard of the intercostal girders, bulb plate section bars are to be welded to the bottom shell plating. These bars to connect to full depth girders in way of the engine and gearbox seatings. A cofferdam to house the echo sounder, sea chest, drain tanks etc. are to be arranged in the double bottom. Each double bottom tank to have two access manholes with bolted plate covers.
[0028] All floor plates and non-watertight girders are to have drainage limber holes with areas 25% in excess of pipe suction areas. Vessel to be longitudinally framed through bottom, side structure and main deck. Side and bottom frame spacing to be 600mm. Mainframes to be of section to Classification requirements. Web frames to be welded to shell, tank tops, knees, floors, etc. in compliance with Rule requirements.

[0029] Main shell plating thickness to be to Classification requirements with all butts and seams welded. Increased thickness of shell to be arranged locally in way of anchor stowage, rudder trunks and generally all other shell openings required by Classification either by doubler or by insert plates. Sea inlet boxes to have plate thickness 3mm in excess of Classification requirements.

[0030] Bow side plating to be to Rule requirements with increased thickness in way of anchor stowage. Anchor pipes to be arranged to ensure free entry and exit of anchors and doubling pads fitted in way of fluke tips. Eye plates to be fitted aft for lifting and handling propellers and rudders. One drain plug of shipbuilders standard pattern to be arranged in each major compartment except machinery rooms.

[0031] In yet another embodiment, Framing of the main deck to be longitudinal, running from aft to as far forward as shape of vessel permits. Longitudinally to comprise plate sections supported in deep transverse beams. Deck to have adequate camber. Stores and auxiliary flats are to be arranged with areas to suit installed equipment. Flats to have no sheer or camber. Flats to be framed transversely. Additional plate thickness and local strengthening to be arranged under deck machinery, davit feet, etc. to Classification requirements. All deck openings to have suitably radiused corners where necessary. Plating to have welded butts and seams and be connected directly to the side shell plating.

[0032] The vessel to be divided into compartments as indicated on the general arrangement plan by means of transverse and longitudinal bulkheads of oil / watertight construction. Bulkheads to be of plain or corrugated construction to suit Builders' construction welded direct to shell, deck and tank top, with stiffeners of bulb plate or inverted angle section.
[0033] The interconnecting engine room bulkheads to have a single watertight horizontal sliding door 1370mm x 560mm approx. Doors to be hydraulically operated both locally and from the forecastle deck, and have open / shut indicator on bridge and damage control stations. Door is to be capable of closing in less than 90 seconds. Minor steel bulkheads inside accommodation generally to be of stiffened or swedged construction to shipbuilders' normal practice.

[0034] Main deck longitudinally and girders to be arranged to maintain fore and aft strength, forming continuity with longitudinal bulkheads where practicable. All girders, transverses, pillars, etc. are to be to Classification requirements. Local pillaring to be arranged under deck machinery to the Owners and Classification Surveyor's satisfaction.

[0035] To be arranged as required by the layout of main and auxiliary machinery and be of welded construction to Classification requirements. Main engine seating to be well stiffened with heavy top-plates, solid floors on every frame and continuous girders, all as required by Classification. Auxiliary seating to be of welded construction and arranged to give convenient access to holding down bolts. The vessel is to have double bottom arranged for the carriage of oil designated for use as fuel as indicated on the general arrangement plan. Two oil fuel daily service tanks are to be constructed integral with each engine room bulkheads, each with a capacity of 7 cu. meters.

[0036] These tanks to have contents gauge and access manhole. Tanks to have air, sounding, filling drains and suction pipes as required by Classification. Air pipes to be taken as high as practicable and be fitted with patent tank valve heads. A combined suction/levelling pipe is to be fitted connecting the Engine Room wing bunkers. Pipe to be complete with valves, fittings, etc. One access manhole of shipbuilders’ standard pattern to be fitted in Engine Room double bottom tanks. Domestic fresh water for the ship is to be carried in the tanks designated on general arrangement plan. Total capacity available for ship use to be approximately 60 m3, i.e. 60 tonnes at 1.0 Sp. Gr. All sounding suction and filling pipes to be fitted to Class requirements, the air pipes having patent tank valve heads. One access manhole of shipbuilders standard pattern to be fitted in each tank.
[0037] All tanks to be tested to the satisfaction of the Classification Surveyor. Upon completion the tanks are to be thoroughly cleaned out and coated in accordance with the painting schedule. Aft and fore peak tanks are to be arranged as indicated on the general arrangement plan for carrying ballast water. In normal ships service only a small percentage may be used for water ballast. Approximate capacity to be 88 m3, i.e. 90 tonnes at 1.025 Sp. Gr. water ballast. Tanks to have air, sounding filling and suction pipes to Classification requirements. One access manhole of Shipbuilders standard pattern to be fitted in each tank space, together with access ladders. All tanks to be tested to the satisfaction of the Classification Surveyor. Upon completion, the tanks are to be thoroughly cleaned out and coated in accordance with the painting schedule.

[0038] Two foam tanks with a total capacity of 5 m3 i.e. 5.6 tonnes are to be arranged port and starboard as indicated on the general arrangement plan, complete with required air, filling and suction pipes. Tanks to be fitted with direct reading gauges. A deep central tank with a combine capacity of 15 tonnes complete with required air filling and suction pipes is to be provided. Supply pipe to be lead to hangar for refuelling of helicopter. Remote reading contents gauge to be fitted with meter sited in hangar area. Small drain tanks each approximately 4-m3 capacity are to be arranged in the Engine Room double bottom for hydraulic fluid and lube oil. Tanks to have air and sounding pipes. Storage tanks for clean lube oil are to be arranged on the Engine Room flat complete with filling and suction pipes.
[0039] Tanks to have sight glasses/gauges. Storage tank to be arranged on Engine Room flat complete with necessary piping and sight glass/gauge. The ship's chain locker to be sited forward of the collision bulkhead and is to be divided on the centreline by a steel bulkhead with hand holes, and arranged to self-stow and carry the specified length of chain cable. Sides and ends of locker to be well stiffened externally to give a clean internal structure and access to locker to be through two watertight manholes from the paint store. Chain pipes dropping from the windlass are to be carried below the level of the beams and be well reinforced with beading at their lower ends. The chain cable and securing pins are to be arranged such that the cables may be slipped without having to enter the locker.

[0040] A perforated steel false floor is to be fitted in the base of the locker above the suction strum and the drainage to be by suction. Hawse pipes to be rolled steel plate with inside diameter of 10 times and wall thickness of approximately 0.4 times the chain cable diameter. Hawse pipes to have solid round bar at shell and deck to take the rubbing of cable. Shell doubler pads of sufficient size to house the anchor fluke tips to be fitted to the side shell plate in each bow. Galvanised steel sliding covers to be fitted over top of hawse pipe port and starboard on forecastle deck, to be complete with locking pin and keep chain.

[0041] Chain pipes to be rolled steel with inside diameter of 8 times the cable diameter with 12mm wall thickness and arranged port and starboard over chain lockers.

[0042] Chain pipes to have solid round bar at deck level and bell mouthed shape at lower end complete with solid round bar for rubbing of cable. Steel covers to be fitted over the top of chain pipes on forecastle deck, to be complete with keep chain. Bilge keels are to be fitted which are not to project beyond moulded side shell and rise of floor lines. The length to be approximately one-third length of the vessel with the final position determined from the parent hull form model tests. Keels to be formed from 300mm x 12.5mm bulb plate section welded to a flat doubler bar onto the bilge strake. End of bilge keels is to be well tapered off and land on doubling pads.

[0043] To be built of welded steel construction with extent and areas shown on general arrangement plan. Heights to be minimum of 2350mm deck to deck. Camber on boat and bridge decks 75mm in half beam. Plate scantlings to be Rule requirements with flat bar or inverted angle stiffeners or swaged construction. Deckhouses and superstructures to be transversely framed. Pillaring to be arranged within the deckhouse to take superimposed loads and reduce beam spans as necessary.

[0044] Helideck landing grid to be of aluminium alloy construction of recognised manufacture. Exterior doors to be as per the Load line requirements with sill heights of 600mm in first quarter of ship’s length from Forward Perpendicular and 380mm in the rest of the ship. Chequered plate steps to be fitted in way of doorways where coamings are 600mm high. Upstands to be arranged of 100mm above deck by continuation of side plating. To be of swedged or stiffened construction in accordance with Shipbuilders standard practice and to Classification requirements. Casings to extend from main deck through four tiers and be of adequate strength to carry the funnels. Minor interior steel bulkheads are to be of swedged or stiffened construction in accordance with Shipbuilders practice. Two funnels, of steel construction, to accommodate engine exhaust uptakes and trunking situated at the aft end of the bridge as indicated on the general arrangement plan. Ventilation louvres are to be arranged in each funnel with fire dampers permanently fitted.

[0045] Steel dog steps to be fitted outside giving access to funnel tops. Permanent access ladders to be arranged on the inside of the funnels to give access to funnel tops if space permits. Exhaust tail pipes to extend above crown plate.

[0046] In one embodiment, equipment and hull fitting is described. The twin rudders are to be conventional streamlined spade type rudders working through a total angle of 70 degrees. Blade to be semi-balanced as for conventional spade type rudders. Rudder stocks and trunks to be supplied to include liners and bearings. Connections are to be arranged such that the rudder may be readily shipped and unshipped. Lifting eyes are to be tapped into the top of each stock together with similar eyes welded to deck head over centre of trunks. At slow speeds of the ship the rudders are capable of generating a side force. To be power operated electric hydraulic gear with steering torque 2 x 10 t-m.

[0047] The steering gear to be capable of moving the rudders through their manoeuvring angle of 35º port and starboard in 21 seconds when the vessel is travelling at service speed with one pump unit in operation. The maximum working angle to be 35º port and starboard. The gear to consist of a rudder actuator motor complete with ring assembly for each rudder stock and spherical self-aligning rudder carrier. The steering gear system to be electronically synchronised and the rudders may operate independently. Two electrically driven pump units each comprising of an electric motor of drip-proof marine type driving a continuous delivery type pump to be fitted in the steering gear compartment. Steering gear control to be from a follow up wheel unit mounted in the forward part of the bridge and two power steering levers, one at each end of bridge wing.

[0048] A panoramic type rudder angle indicator to be mounted at forward end of bridge with two repeaters mounted at each bridge wing. Emergency steering arrangements to be as required by Classification regulations in the form of independent and separate electrical systems with non-follow up electric steering lever mounted on bridge control panel. The steering gear system to be connected into a solenoid control box for coupling of the autopilot. Control panel mounted in bridge with indicator lights for failure, selector switch for level controls, pump units or autopilot, rudder angle indicator and alarm lights.

[0049] Alarm relay cabinet to be mounted in the Machinery Control Room giving warning of overload, loss of supply, low oil level. For reduction of rolling motions of the ship an active stabilizer system with a non-retractable fin on each shipside may be provided.

[0050] Fins may be arranged in bilge range in such a manner that they do not protrude beyond shipside. Area of each fin may be determined in accordance with detailed design. A hydraulic power unit at each fin, driven by electric motor, may execute the fin movements. For automatic control of fin movements, a gyro control system may be provided, depending on roll angle, rolling period and metacentric height. Switching on and off control may be performed from the Bridge. The ship may be installed with one side thruster driven by harbour D.G set via connected hydraulic pumps and motors.

[0051] Tunnel may be provided for bow thruster with grids in front of shell opening with bars perpendicular to streamlines. The hydraulic bow thruster package may comprise of following One fixed pitch propeller unit with built on hydraulic motor
_ One no manifold with safety valves, steering valves, manometer, and flanges.
_ one cooler unit
_ one filter unit
_ one hydraulic remote controlled drop in panel for installation on Bridge console
_ One hydraulic pump unit driven by step up gear box. The gear box may have clutch
in/ clutch out controls.

[0052] The vessel may be provided with following equipment for limited pollution control capability. Containerised 250M hi-sprint boom suitable for oil containment in open sea. This container may also have D/D self-contained compressor-cum winder for RO Boom. Disc type skimmer of capacity 30 TPH with D/D self-contained hydraulic power pack Floating Hypalon tanks for storage of recovered pollutants. 2T @ 5.0 M working radius capacity telescopic electro-hydraulic crane for handling of oil skimmer and recovery of RO Boom from sea. D/D self-contained dispersant spraying system with dismountable type 6M long spraying arms at both ends. (Two off 2.0 CUM capacity built-in tanks may be provided for loading of dispersant chemicals whenever required.

[0053] In another implementation, a windlass mounted on welded steel seatings on forecastle deck. Single cable lifters and single warping head and arranged as one per cable.

[0054] Each windlass to comprise a electric motor with gear transmission to the main shaft which has one warping end and single cast steel cable lifter suitable for the Rule diameter grade CC2 special steel stud link chain cable. The cable lifter is to have a clutch and be fitted with a robust hand brake. Further, one electrically driven vertical capstan to be fitted on the aft working deck as shown on the general arrangement plan. Two telescopic cranes having a lifting capacity of 2t at 5m radius may be installed at the quarterdeck to assist in pollution control activities. Cranes to be mounted on welded seating with deck strengthened to suit Classification requirements. Cranes to be electro-hydraulically powered with power pack sited in an adjacent compartment.
Controls to be mounted locally on the cranes.
[0055] In another embodiment, Steel watertight doors are to be fitted to accommodation and store spaces on main deck and to deckhouse or forecastle deck. Watertight doors to have six spring-loaded cleats to Class requirements and have a fixed glass light with deadlight cover in way of accommodation entrances. Bridge doors to be of steel, hinging with plate glass windows. All doors to have positive locking and hold back arrangements. Sickbay external door to be suitable for access with stretcher.

[0056] Hinged steel watertight doors are to be fitted below main deck level at the following positions:
Steering flat to access alley in access alley level with aft face of ballast deep tanks one horizontally sliding watertight door is to be fitted giving access between main machinery room and auxiliary machinery room. Sliding doors to operate hydraulically with self-contained power packs fitted adjacent to door. Capable of operation locally from each side of door and remotely from main deck. Indicators to be provided by means of coloured lights in the bridge and damage control position. Emergency hand pumps with control valves to be fitted for each door at main deck level.

[0057] All hatch coaming heights, closing and securing arrangements to be Classification requirements. Forepeak store hatch on the main deck is to have a clear opening of approximately 600mm x 600mm with rule height coaming and a hinged watertight cover.
[0058] Escape hatches on forecastle and main decks to have a clear opening of approximately 600mm x 600mm rule height coamings and hinged watertight covers operable from both sides. Ladders to be of mild steel construction and fitted as indicated on the General Arrangement plan. Sloping deck ladders to have plate strings, non-slip treads and two handrails of mild steel tube. Mast ladders to consist of steel square section rungs joggled upwards at each end to prevent foot slipping off. Vertical deckhouse ladders to be formed from flat bar strings and square section rungs. One aluminium alloy shore gangway to be supplied and stowed in agreed position on forecastle deck. Gangway to be complete with shore wheels, securing ropes, portable self-locking stanchions and hand ropes. Two no Accommodation ladders to be supplied complete with welded eye plates for in use and storage. Life raft boarding ladders to Authority approval and requirements to be supplied and stowed adjacent to boarding position on forecastle deck. Ladders inside deep tanks and peaks, and under hatches to be of mild steel construction with square section rungs welded to flat bar strings where space permits, otherwise dog steps. Chain locker centre division plate to have foot holes cut in for full depth. Internal stairs or ladders within accommodation spaces to be of steel construction with non-slip treads and fitted with handrails on both sides. Slope of stairs in general not to exceed 60 degrees.

[0059] Two double roller fairleads are to be fitted, on the fore part of the main deck and quarterdeck each, for mooring lines and springs. Units are to be welded to deck and bulwarks as the arrangement permits. Cast steel pipes size 356mm x 254mm are to be welded into the bulwarks in the following positions port and starboard. Mooring bollards of tubular steel construction approximately 250mm diameter to be positioned as follows port and starboard.
_ 2 nos. on no1 deck abreast windlass
_ 1 no foreside of windlass
_ 2 nos. on quarter deck
_ 2 nos. at amidships on no1 deck.

[0060] Cast steel pipes size 356mm x 254mm are to be welded into the bulwarks in the following positions port and starboard.
_ 3 on forward end (one on centreline)
_ 2 on main deck at sides

[0061] To be fitted around monitor platforms, navigating bridge top, bridge deck, boat deck and forecastle deck as indicated on the General Arrangement Plan. Rails to be fitted to all sloping ladders and around ladder way openings. Spacing and number of guardrails to be in accordance with Regulation 25 of the 1966 Load line Convention. Top rails to be 38mm mild steel pipe, middle and bottom rails to be 19mm solid round rod or steel pipe. Stanchions to be 75mm x 12mm flat bar, spaced approximately 1200mm apart and welded direct to deck or house side. Rails and stanchions on bridge top in way of compass radius to be of aluminium alloy. Where required, stanchions in way of life rafts, and gangways platform are to be hinged drop type with wire rope rails complete with snap fasteners, bottle screws, etc. Storm rails of 38mm diameter mild steel pipe to be fitted around deckhouse. Grab rails in accommodation passageways to be 38mm diameter plastic coated piping or plastic capped flat bar and in passageways through lower deck working areas to be of 38mm diameter mild steel pipe. Handgrips are to be fitted in all WC and shower cubicles. A handgrip is to be fitted adjacent to all vertical manholes.
[0062] The emergency generator, switchboard and associated equipment are to be housed in a
Compartment as indicated on the general arrangement plan. Space to have watertight entrance door and adequate ventilation to suit the installed machinery requirements. Seatings are to be arranged for alternator set and switchboard. Lifting eyes to be fitted at deck head for maintenance withdrawals. Oil fuel header tank to be built in.

[0063] A deck store to be sited starboard side aft on quarterdeck and arranged for the stowage of petrol and lubricants. Access to be through a watertight steel door and to be fitted out with racks and shelving to contain drums and containers. Good ventilation to be provided with spark arrestors fitted to vent heads.

[0064] Boatswain’s Store to be arranged in the forepeak area to port side on the main deck with access through hatch leading through thrusters’ room. Naval Store and Gunner store are arranged port and starboard side, aft of Spare Gear store and arranged with a single tier of shelving to outboard side and lock-up cupboards against fore and aft bulkheads.

[0065] Further, Bridge windows to be of weld-in type steel framed with aluminium alloy or bronze inserts all windows are to have glass thickness in accordance with or equivalent to BSS 3925:1965. Bridge front windows to be approximately 700mm deep x 800mm wide fixed type and consist the central window having a Wynstrument straight-line windscreen wiper. Two other fixed windows also to have Wynstrument wipers fitted. Bridge side windows to be all fixed type comprising eight at approximately 800mm wide x 700mm deep. Accommodation windows are to have aluminium alloy frames, being either fixed, or fully opening as indicated on the General arrangement plan. Windows are to be approximately 600mm deep x either 1000mm or 500mm in width. Fibreglass trim boxes to be fitted at windows in way of all cabin linings. Storm cover plates are to be provided for windows on lower deckhouse front as required by Classification. Windows to have lock nuts fitted in lieu of toggles to suit air conditioning requirements.

[0066] Sidelights to be fitted in accommodation and store spaces where indicated on the general arrangement plan and detailed in the specification details of cabins and store spaces. All sidelights to be of Shipbuilder's standard type and comply with or be equivalent to BSS 3024:1966. Deadlights to be fitted to all sidelights where required by Classification. Sidelights to be open or closed type as indicated on the general arrangement plan. Forecastle tween deck sidelights to be 300mm in diameter and fitted in shell tubes for protection. One access manhole to be fitted to all tanks, compartments and void spaces not fitted with a hatch or door. Double bottom tanks in Engine Room are to have two manholes. Manhole covers to be shipbuilder's standard pattern, secured on stud bolts with oil/watertight packing ring. Covers on manholes are to have a single lifting handle. The vessel to have mast in position indicated on the General arrangement plan.

[0067] The mast may be positioned to meet COLREG and other relevant Regulations and be constructed from stiffened aluminium plate complete with light brackets, radar platforms, aerial sheaves, access rungs and safety hoops. Mast is to be self-supporting. Tubular steel pole mast is to be arranged on the stern to carry the ensign flag. A similar mast of tubular steel construction is to be positioned at the stem head. Masts are to have necessary flag halyard sheaves.

[0068] All rigging fittings are to be to Classification and British Standard Specification requirements where applicable. Blocks and aerials, yardarm, signal flag and shape hoists to be arranged on masts. Generally, running rigging to be in galvanised flexible steel wire rope with standing rig in galvanised steel wire rope. Lifelines where required by Classification to be arranged on main deck. Eye plates for lifting machinery components, shafting, etc. are to be suitably positioned and where used for installation purposes to be left insitu.

[0069] Covers of heavy waterproof canvas are to be supplied and stowed on board, being suitable for the following items: chain pipes, monitors, searchlights, compass, windlass, capstan, inflatable boats.

[0070] The offshore vessel 200 may provide lifesaving equipments like lifrafts, lifebuoys, lifejackets, line throwing apparatus, distress signals, rescue boats, firefighting system and the like. The offshore vessel 200 may further provide air conditioning and ventilation system. The offshore vessel 200 may further comprise miscellaneous equipment like Three binoculars with box, One star globe, One distance meter, One range finder, telerometer 89 or equivalent, One aneroid barometer, One barograph, One windvane, One wet, dry bulb thermometer, One batten burg.

[0071] The offshore vessel 200 may comprise a television, entertainment, audio and special system, sound powered telephone system, a portable PA system, intercommunication system, broadcast system, navigation lights, signalling lamps, call bell system, fire detection system, helo starting arrangement system, cabin fan system, desk lights, portable headlamps, emergency lighting system, boat launching station lights, general alarm system, 24 volt DC system, distribution system, shore connection facility, transformers, engine room alarm and monitoring system, power management system, safety system, cooling system, lubricating oil system, engine room piping systems, oily bilge water separator, fresh water generating equipment, main gear transmission plant, fuel oil system and many more.

[0072] Exemplary embodiments discussed above may provide an advantage, this may include the following.

[0073] Some embodiments of the offshore vessel 200 provides good sea-keeping and manoeuvrability.

[0074] Some embodiments of the offshore vessel 200 provides stability to meet sea conditions up to sea state 7.

[0075] Some embodiments of the offshore vessel 200 is configured for survivability and minimised radar return Sea worthy with the capability to undertake operational missions up to sea state 7.

[0076] Some embodiments of the offshore vessel 200 provides helo operations for up to sea state 5.

[0077] Some embodiments of the offshore vessel 200 provides increased deck area at aft.
[0078] Some embodiments of the offshore vessel 200 provides Enhanced helideck capable of accommodating Advanced Light Helicopter (ALH) and a fixed helicopter hangar.

[0079] Some embodiments of the offshore vessel 200 provides embedded modularity without compromising on baseline capability.

[0080] Some embodiments of the offshore vessel 200 provides integrated airborne capability to increase surveillance range.

[0081] Some embodiments of the offshore vessel 200 provides provisions to incorporate firefighting (Fi-Fi) requirements & fitment of bow thruster for better position keeping.

[0082] Although implementations for the offshore vessel 200 have been described in language specific to structural features and/or methods, it is to be understood that the appended claims are not necessarily limited to the specific features or methods described. Rather, the specific features and methods are disclosed as examples of implementation for the offshore vessel 200.

,CLAIMS:

1. An offshore vessel (200), wherein the offshore vessel (200) comprises:
a hull (102), wherein the hull (102) has a V cross section at a bow side of the hull (102) and a transom side of the hull (102);
a deck (202) mounted on a top of the hull (102);
a plurality of fixed fin stabilizers (206), wherein the plurality of fixed fin stabilizers (206) are mounted to an outer surface on a bottom half of the hull (102);
a twin-funnel exhaust, wherein the twin-funnel exhaust is mounted on the deck (202); and
a plurality of bulkheads (204), wherein the plurality of bulkheads (204) are located on an inner bottom surface of the hull (102).

2. The offshore vessel (200) as claimed in claim 1, wherein the hull (102) comprises a bilge, wherein the bilge is round.
3. The offshore vessel (200) as claimed in claim 1, wherein the deck (202) comprises a helideck (210), and a fixed helicopter hangar (208).
4. The offshore vessel (200) as claimed in claim 1, wherein one or more fire-fighting equipment are mounted on the deck (202).
5. The offshore vessel (200) as claimed in claim 1, wherein the hull (102) comprises a plurality of bow thrusters (212), wherein the plurality of bow thrusters (212) are coupled to the outer surface on the bottom half of the hull (102).