US3754523A - Icebreaking tank ship - Google Patents

Abstract

An icebreaking tank ship has an elongated hull with a bow and stern and a catamaran arranged above and connected to the hull, the elongated hull moving substantially under the icepack while the twin hulls of the catamaran are arranged to cut through the icepack, the bridge of the catamaran being spaced above the icepack.

Description

United States Patent 119 3/1972 Haahemi 114/40 X Devine Aug. 28, 1973 [54] ICEBREAKING TANK SHIP 3 1,817,742 8/1931 Escobedo 114/ 16 R 3,494,318 2/1970 Kataumura.. 114/235 R [751 Devin" 3,537,413 11/1970' Farrell 114/43.s [7 3] Assignee: Esso Research and Engineering Company, Linden, NJ. Primary Examiner-Milton Buchler 22 Filed: N 19 1 1 41 1 9'" !?'7 1!1-- 135F129 1 0v 19 1 Attorney-Thomas B. McCulloch, Melvin F. Fincke [21] APPl- 2001307 and Timothy L. Burgess et a1.

[57] ABSTRACT [52] U.S. Cl. 114/40, 114/61, 114/16 [51] Int. Cl 1363b 35/08 cebmkmg '1 flamed a 58 Field ofSearch 1 14 40-4'2,43.5,44, and and a mans 11 4 l 49 16 235 connected to the hull, the elongated hull movmg substantially under the icepack while the twin hulls of the 56] References Cited catamaran are arranged to cut through the icepack, the

UNITED STATES PATENTS bridge of the catamaran being spaced above the ice- 1:. 3,429,287 2/1969 Uram 114/16 R P 1 Claim, 4 Drawing Figures PATENTED MIC 28 I975 ff Tr INVENTOR. WALTER B- DEVINE,

THOMAS B. Mc CULLOCH ATTORNEY.

ICEBREAKING TANK SI-IIP BACKGROUND OF THE INVENTION above the cargo-carrying hull so that the icepack is below it. In its more specific apsects, the invention involves a triple-hulled vessel having. an elongated cargocarrying hull and catamaran hulls connected to the lower hull and provided with means for cutting the icepack.

2. Description of the Prior Art It is known to provide submarine type vessels with a single hull projecting through the icepack. These vessels tend to follow cracks in the icepack and roll and thus have little stability. It is also known to provide icebreaking vessels with detached or connected prows having unbalanced weights which rotate to break the ice with a hammer effect. Likewise, icebreakers with extensions on the bow which extend under the pack ice and break it by an upwardly extending cam force. Knife blades on the prows of icebreakers are also known. However, no one heretofore'has provided a combination as described and claimed here of an elongated hull with upwardly extending bow ice knife and catamaran hulls which cut through the pack ice. The present invention is, therefore, new, useful and unobvious. The following listed U. S. Pat. Nos. were considered with respect to this invention: 499,296; 857,766;'993,440; 1,500,000; 3,045,628; 3,130,701; 3,521,590; 3,572,273.

SUMMARY OF THE INVENTION The present invention may be briefly described and summarized as involving an icebreaking vessel having an elongated hull and a bow and stem for use in Arctic waters and having parallel wing walls which may be approximately midship of the elongated hull forming parallel hulls each having an ice bow and stem, the parallel hulls being connected to the elongated hull to extend above ice water line while the elongated hull extends longitudinally substantially below the icepack. The outer of the wing walls extending outwardly from the elongated hull such that ice is causedto break downwardly and outwardly of the elongated hull. Bridge means are spaced vertically from the elongated hull and interconnect the parallel hulls. The elongated hull is adapted to carry liquid or dry cargo such as oil or ore.

The elongated hull has upwardly extending curvilinear ice knife extending from the bow toward the stern a sufficient distance to cut under the icepack asthe vessel moves ahead or astern.

BRIEF DESCRIPTION OF THE DRAWING The present invention may be further illustrated by reference to the drawing in which FIG. I is a top partial sectional view of the ship of the present invention;

FIG. 2 is a side elevational partial sectional view of the present invention;

FIG. 3 isa front view of FIGS. 1 and 2; and

FIG. 4 illustrates the vessel in ice breaking position in Arctic waters.

DESCRIPTION OF THE'PREFERRED MODES AND EMBODIMENT WITH REFERENCE TO THE DRAWING Numeral l l designates the hull of an elongated vessel provided with a bulbous bow l2 and having wing walls 13 which extend outwardly from the walls 14 of the hull II. The wing walls I3 form hulls IS with walls 16 which are joined to form ice prows I7 and stems 18. In short, spaced above the hull 11 are hulls 15 which are connected together by bridge means 19 to form a catamaran designated by the numeral 20.

The hull 11 is strengthened with transverse bulkheads 21 and longitudinal bulkheads 22 which form tanks such as 23 which may be used for liquid or dry cargo such as oil or iron ore and the like. Arranged on the bow of the vessel 11 and extending about 15 to 30 percent of the hull length are knives 24 which serve to cut the icepack as the hull 11 moves ahead or astern in Arctic waters.

The hull 11 is provided with screw means 25 which may be two or more in number and trim control means 26 as well as steering means 27. I

Stack means 28 extend upwardly through the hulls 13 to the atmosphere from an engine room 29 which may contain one or more steam engines, diesel engines, or nuclear power means. These stacks may be used to vent gases, smoke, vapors, steam and the like.

In FIG. 1 the ice water line is shown as a shaded area 30 which represents the cross-sectional area of hulls 15 with the ice being broken as will be more clearly understood from the description of FIG. 3. The stem 31 of the vessel overhangs the trim control means 26, the steering means 27 and the screw means 25. I

Referring to FIG. 2, it will be noted that the control cargo tanks 32 of the elongated hull 11 have access and ventilate to the atmosphere via the ullage spaces 33 located in the wing walls 13. The ullage spaces 33 extend upwardly in the hulls 15 and are closed by vented hatches 50. In case of leaks which may occur in hull walls 14, the only cargo liquid lost would be that amount in space 33 which extends about the water line as represented by D in FIG. 2. Pressure equalization would contain the remainder of the cargo liquid. The bridge means 19 providing officers and crew quarters and being spaced above the hull 15 a sufficient distance so that the icepack moves beneath the bridge 19 while the hull 11 is substantially below the icepack. Thisdistance may be in the range of about 30 to about 50 feet. In FIG. 2 the ice water line is indicated by the numeral 42 and it is substantially cut by the ice bows 17 of the hulls 15, which causes the ice to move downward and outward from the hull 11. The ice knife 24, as stated, extends rearwardly on both sides of the hull about 15 to 30 percent of the hull length and serves to cut loose the ice peaks formed beneath the ice layer while the ice bows 17 are breaking up the ice layer at the surface. The ice peaks below the ice layer are usually formed by ice particles and are usually unconsolidated masses of ice and vary in size, depth and spacing.

The present invention is quite advantageous and useful in that the vessel is provided with two verticalfins (hulls) transversely separated which penetrate the ice surface, while most if not all of the elongated hull is below the ice water line. The fins or hulls provide a minimum resistance to icebreaking, while providing the necessary stability and reserve buoyancy for a safe operation.

The vessel may be generally described as a semisubmersible catamaran icebreaking vessel consisting essentially of a main hull with two wing walls on each side extending above the upper deck of the main hull. The wing walls are joined at the top with the forward part supporting a bridge structure which houses the ships personnel and controls for the ship.

When the vessel is in open water, it is operated in the usual manner with freeboard. When the vessel enters the ice, water ballast is added to the elongated hull and wing walls forming the twin hulls until the main hull is submerged and only the twin hulls are cutting through the ice. The sum of the width of the twin hulls is about one quarter of the width of the main hull, thereby reducing resistance of the ice, making forward progress of the vessel easy and fast. The twin hulls are positioned and shaped in such a way that all the broken ice is forced outward and downward away from the main deck of the main hull. The shape of the twin hulls at the ice water line is such that they taper to a narrow after end. The distance between the wing walls of the twin hulls at the ice water line is closer at the forward end and a greater distance apart at the after end. This distance may be from about 2 percent to about 6 percent the length of the catamaran hulls. This spread permits the broken ice between the twin hulls to move freely aft. The outboard shape of the wing walls of the twin hulls at the ice water line is curved from forward to aft, while the inboard'side is generally a straight line.

The two hulls are utilized in this invention to provide adequate transverse stability to a semi-submersible hull while a single fin centrally located does not provide the same degree of stability as the present invention. In addition, the danger of a single fin is that it will tend to follow a crack in the ice, and should the crack lead at an angle to the forward motion, a large vessel with little stability will roll rather than tum. The twin hulls fight this tendency in two ways: first, the amount of transverse stability is about 500 times greater, and secondly, it is unlikely that racks leading from two spaced apart hulls would lead in the exact same direction. In the event that the ice force did start the vessel to roll, two additional forces come into play. First, the forward ice knife on the submerged hull begins cutting into the surface ice, tending to slow the vessel down. Second, as the vessel continues to roll, the main deck emerges and the wider portion of the wing wall submerges, both tending to stop the vessels roll. The additional stabilizing forces begin to act when the angle of roll is about 12. The maiximum righting arm occurs around 25 which is greater than on conventional hulls.

The longitudinal stability of this invention is much less than that of a normal hull. The ice-breaking forces at the far portion of the wing wall will tend to trim the vessel by the stern. By placing the ice how well aft to the forward end of the vessel, say about 20 percent to about 40 percent of the vessel length, the trimming movement is significantly reduced. The ridge ice knife at the bow of the elongated hull is shaped to cut through ridges but not to give any net vertical force to the bow of the vessel, either up or down. The trim control at the stern provides the necessary balancing force to keep the vessel on an even keel. The vessel will cut through ridges rather quickly so that the very large inertia of the vessel will prevent it from suddenly taking any large trim angle.

Both rudders and trim control surfaces are placed in the propeller wash so that trim and turning forces can be generated even with the vessel standing still in ice or water. The trim control can also be useful in approaching a loading facility in the ice. As ballast is removed to bring the main deck out of the water, the vessel must be trimmed by the stem to clear all the ice off the deck. As the bow emerges, the ice will be pushed aside, forming an open water area for the vessels hull. The semisubmersible hull form of limited ice resistance can burn fossil fuels, whereas a submarine with no ice resistance requires the more costly atomic or chemical power. The semi-submersible has the added advantage of primary depth control built into the hull shape, whereas a submarine must rely on pressure sensors, mechanical control surfaces and very fine weight control.

Machinery space in the semi-submersible of the present invention is centrally located longitudinally under the wing walls to minimize the trimming movement in case of flooding.

All of the above-mentioned features may apply to any vessel no matter what its function. The following will describe features that are particularly useful for a vessel designed to carry petroleum products in bulk or liquid form.

A semi-submersible icebreaker is particularly suited for the carriage of liquid products that are, broadly speaking, near the same density as water. The wing walls must have sufficient stability and reserve buoyance to prevent sinking in the event of a rupture. The amount of stability and reserve buoyance required is directly related to the amount of void spaces in the underwater portion of the vessel. Liquid cargoes tend to fully occupy the submerged hull. A change in buoyancy in the event of rupture in a compartment already full of a liquid is very small. The size of the wing walls necessary to compensate for such a change is very small. This is not the case in carrying ore cargoes, for such vessels require a great quantity of void space to support high density ore.

The present invention, when designed for carrying oil with a density lower than that of water, offers simplicity of design and safety of operation, particularly suited to the present configuration. When the underwater hull other than machinery spaces is full of oil, its buoyancy will be positive; that is, the hull will tend to float. The wing walls above the water surface will then be used to carry water ballast in order to sink the main hull to its operating depth and the ice water line. The twin hull volume and configuration then serve a number of unique functions in the tank vessel, as follows:

1. Provides transverse and longitudinal stability;

2. Provides the necessary above water ballast volume to submerge the hull to the appropriate ice water line;

3.Provides the ullage space for the cargo tanks to eliminate free surface in the submerged hull;

4. Provides a location for the cargo tank vents;

5. Provides for air location to the fossil fuel machinery and exhaust spaces for gases of combustion;

6. Provides access between the navigation bridge and quarters to the machinery spaces including shaft tunnels;

7. Provides a collision rupturing wing ballast tank which will cause water to flow out of the hull,

thereby adding buoyancy instead of losing buoyancy.

A further advantage of carrying oil products in such a hull is demonstrated in the event of grounding. The small cross-sectional area of the ullage space above and below the ice water line will quickly equalize the pressures between the outside waterhead and the internal oil head in the event of a rupture and very little flow in or out will occur, thereby significantly reducing any pollution hazard.

The present invention provides a simple and unobvious tank ship which is readily adapted for use in Arctic climes and in Arctic waters and provides for transportation of either liquid or dry cargoes.

The ship of the present invention may have an elongated hull 1,000 feet in length with a beam of 200 feet. The catamaran hulls will be suitably sized for the length and beam of the elongated hull.

The nature and objects of the present invention having been completely described and illustrated and the best modes and embodiments set forth, what I wish to claim as new and useful and to secure by Letters Patent l. The combination of an elongated hull having a bow and stern and a catamaran having a bridge connecting the catamaran, said catamaran being arranged above and connected to said hull, said catamaran having sufficient reserve buoyancy to prevent sinking in the event of a rupture of the elongated hull;

said elongated hull floating below ice water line in a body of water when ballasted or loaded andsaid catamaran being formed to cut through an icepack in said body of water; said catamaran having outer wing walls which are an upward continuation and extension of outer walls of the elongated hull and the upward extension of the outer wing walls of the catamaran are positioned and shaped so that they extend upwardly and outwardly to force broken ice outward and downward away from the elongated hull.

Claims (1)

1. The combination of an elongated hull having a bow and stern and a catamaran having a bridge connecting the catamaran, said catamaran being arranged above and connected to said hull, said catamaran having sufficient reserve buoyaNcy to prevent sinking in the event of a rupture of the elongated hull; said elongated hull floating below ice water line in a body of water when ballasted or loaded and said catamaran being formed to cut through an icepack in said body of water; said catamaran having outer wing walls which are an upward continuation and extension of outer walls of the elongated hull and the upward extension of the outer wing walls of the catamaran are positioned and shaped so that they extend upwardly and outwardly to force broken ice outward and downward away from the elongated hull.

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