DESC:FIELD OF INVENTION:
The present invention relates to an underwater fendering arrangement of tugboats for submarines. More particularly, to develop the tug which is capable of Bollard pull of 50 Ton for pulling, pushing, towing alongside ships/ submarines. The present invention further relates to a method of arrangement of tugboat fender structure.

BACKGROUND AND PRIOR ART:
The tug is designed to assist naval ships including Aircraft carrier & submarines, in docking, un-docking, berthing & un-berthing/ turning/ manoeuvring in confined waters/ harbours and to undertake “cold move” of Naval ships & submarines without inflicting any damage to the tug or the vessel/submarine being assisted. Any such damage would not only result in loss of time and cost but also hampers mission ability and affects the security of the country.

Conventional fender arrangement (around the shell at main deck) will be effective in handling of surface vessels, however the same is not effective in handling of submarines as the contact point will be below waterline and the tug requires a special arrangement of fenders to handle submarines. Alternative fender arrangement being used (Fenders placed vertically along sections at various longitudinal locations on outer shell) has been studied and found that there would be significant increase in resistance, increase in the weight of the tug and it would also cause higher heeling moment on the submarine.

A tugboat fender absorbs the shock and pressure while maneuvering ships. These tugboats fenders need to reliable and stable, and have high abrasion resistance under extreme conditions. They are usually made of rubber. They are further designed to absorb shock and pressure impact and improve grip when pushing.

CN108248792A discloses a tugboat fender structure of tugboat equipment. The structure comprises a lifting cylinder, a fender device and a rubber welding fixing frame. Further, the fender device is fixedly arranged on the outer side of the fixing plate.

US2015191224A1 discloses a hull of a tugboat for towing/assisting a vessel. The said hull has a bottom, a bow, a stern, an underbody provided with a first keel and
a second keel, the first keel being parallel to and facing the second keel. Further, pushing fenders are placed in axis of the propulsion unit.

US7509920B2 discloses an inflatable fender system for protecting a watercraft from damaging contact with a permanent object, such as a dock, wharf, piling and rafted watercraft. Further, tubular fenders are arranged on the side of the hull.

US2022126956A1 relates to reducing a method of handling a mooring line having a first end portion attached to a vessel and second end portion of a mooring line with a moveable arm mounted to a towboat. This method also securing a mid-portion of the mooring line between the first end portion and the second end portion with respect to the towboat. Further, at least one fender projects outwardly from the hull of towboat to prevent damage and the plurality of compressible rubber tube fenders are arranged around the perimeter of the hull and mounted on the gunwale of the towboat.

US2022009602A1 relates to reducing a tugboat for assisting a marine vessel to maneuver and it comprises an engine driving one or more propulsors with a controllable direction of thrust, a towing line for establishing a pulling connection between an assisted vessel and the tugboat, a first sensor arrangement for sensing the size and direction of the pulling force that the towing line exerts on the tugboat and second sensor arrangement for sensing the orientation of the tugboat. The collision prevention system is integral part of the electronic control has assigned a first and second collision zone around the boat and it is configured to assign a category to each detected obstacle like watercrafts, ships, navy vessels, cruise ships, ferries.

CN113895581A discloses a pushing combination barge and a pushing wheel. Further, rolling fenders are arranged at both ends of the groove at the rear of the barge and elastic fenders are arranged on the side of the push wheel. During the process of driving the push wheel into the groove at the rear of the barge, the elasticity of the push wheel fenders and the rolling fenders of the barge are constantly colliding and contacting.

Non-Patent Literature tilted ‘Design of Tugboat’ refers to design of a tugboat that CN201552548U discloses a top-mounted ball valve dismantling tool comprising a positioning plate with two positioning holes. However, the tool is connected by hinges, and the said hinges are more prone to damage when large thrust is applied.

CN203956862U discloses a ball valve disassembly and assembly tool comprising a tensioning device comprising a rotating device, a screw rod connected with the rotating device, a stretching device, a spring, a spring seat and a power device. As a result, there is a need for a simple tool that can dismantle the ball valve effortless and with minimal parts.

The existing conventional approach would result in direct contact between the tug and the submarine and might cause damage (or) there will be a need for an additional pontoon fitted with all round fenders between submarine and the tug to eliminated any risk of damage to surface of contact.

The transverse fender arrangement would result in higher resistance (reduced design speed) and would also cause higher heeling moments on the submarine. FRP casing (if present on submarine) may come in contact with it and might get damaged.

Thus, underwater fendering arrangements of D-type fender at the bow, forward quarter, amidships, and in-line with the propulsion unit, skeg of the tugboat for submarines with capable of bollard pull of 50 Tons, wherein, rubber cylindrical fenders arranged on the bow side of the tug boat and tubular fenders arranged on side of the hull and inflatable fender system for protecting a watercraft, pushing fenders are positioned on the axis of center of the propulsors is disclosed in prior arts. However, underwater fendering arrangements using D-type fender at the bow, forward quarter, amidships, in-line with the propulsion unit, and skeg of the tugboat for submarines with capable of bollard pull of 50 Tons is not disclosed, and thus there is need for the same.

SUMMARY OF THE INVENTION:
It is an object of the present invention to provide an underwater fendering arrangements using D-type fender at the bow, forward quarter, amidships, in-line with the propulsion unit, and skeg of the tugboat for submarines and capable of bollard pull of 50 Tons.

It is another object of the present invention to provide an underwater fendering arrangement of tugboat in accordance with MIL-STD-2040 for handling of submarines.

A novel fender arrangement, wherein multiple fenders placed along the length of the tug, is disclosed herein. The fenders are oriented along the flow around the hull of the tug to have reduced resistance and better contact and handling capability.

BRIEF DESCRIPTION OF DRAWINGS:
Figure 1 illustrates an embodiment of the invention.
Figure 2 illustrates an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION:
The invention is described herein in detail with the help of figures appended at the end of the specification. The figures illustrate the preferred embodiment as well as other embodiments that define the scope of the present invention. However, it may be understood that the figures presented herein are intended to exemplify the scope of the invention only. The person skilled in art may note that by no means the figures limit the scope of the invention. Any variation in the drawings by any other person will be falling in the scope of the present invention.

The present invention provides an underwater fendering arrangements which comprises D-type fender at a bow, forward quarter, amidships, in-line with the propulsion unit, and skeg attached to a tugboat by means of a tug for submarines and capable of bollard pull of 50 Tons.

In a preferred embodiment, the tug of the underwater fendering arrangement of tugboat comprises an iaw MIL-STD-2040 for handling of submarines.

In a further preferred embodiment, the tug of the underwater fendering arrangement is an all-round tug for pushing/ pulling and for towing alongside ships/ submarines

In a further preferred embodiment, the said tug is capable of developing a bollard pull of 50 ton for pulling/ pushing/alongside towing.

In a preferred embodiment, the said tug is further capable of:
(a) assisting large naval ships, including aircraft carrier and submarines, in berthing and unberthing/ turning/ manoeuvring in confined waters/ harbours
(b) undertaking the 'cold move' of naval ships and submarines, within port limits
(c) providing assistance for dry docking/ undocking of ships and to assist movement in/ out of tidal basins
(d) moving non self-propelled vessels, such as ammunition/ water/ fuel barges and lighters, within port limits
(e) assisting warships during inclement rough weather to prevent accidental damage
(f) providing afloat firefighting cover/ assistance to ships alongside/ at anchorage
(g) un-beaching grounded vessel
(h) carrying out search and rescue

In a further preferred embodiment, the arrangement of the underwater fender is at the bow, forward quarter, amidships, and in-line with the propulsion unit, skeg with D-type fender arrangement

In a further preferred embodiment, the maximum height of the said tug from light water line with collapsible mast is 7.5m.

The foregoing descriptions are merely specific embodiments of the present invention, but are not intended to limit the protection scope of the present invention. Any variation or replacement readily figured out by a person skilled in the art within the technical scope disclosed in the present invention shall fall within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
,CLAIMS:1. An underwater fendering arrangement for submarine comprising:
a fender at a bow, forward quarter, amidships, in-line with the propulsion unit; and
a skeg attached to a tugboat.

2. The arrangement as claimed in Claim 1, wherein the fender is a D-type fender.

3. The arrangement as claimed in Claim 1, wherein the skeg is attached to the tugboat by means of a tug.

4. The arrangement as claimed in Claim 1, wherein the tug is an iaw MIL-STD-2040 for handling of submarines.

5. The arrangement as claimed in Claim 1, wherein the tug is capable of bollard pull of 50 Tons.