US3868920A

US3868920A - Semi-submerged cargo transport system

Info

Publication number: US3868920A
Application number: US194633A
Authority: US
Inventors: Joseph F Schirtzinger
Original assignee: Air Logistics Corp
Current assignee: Air Logistics Corp
Priority date: 1970-09-23
Filing date: 1971-11-01
Publication date: 1975-03-04
Anticipated expiration: 1992-03-04

Abstract

There is provided a semi-submerged cargo system for the transport of cargo under ice. The system comprises a submerged vessel having navigational and cargo sections and a propulsion section; connected to a surfaced bridge, housing the crew and controls, by an ice-cutting mast. The propulsion section drives the vessel under the surface of the ice. Although the propulsion section is preferably an integral part of the vessel, it may exist as a separate tug which tows or pushes the vessel.

Description

O United States Patent 1 91 [111 3,868,920 Schirtzinger 1 -Mar. 4, 1975 [54] SEMl-SUBMERGED CARGO TRANSPORT 3,494,607 2/1970 Rusch 114/219 SYSTEM 3,517,633 6 1970 Wanzer 114/151 3,521,592 7/1970 Rosner et a1 114/42 [75] Inventor: Joseph F.Sch|rtz|nger, Pasadena, 537 4 1 970 Calif. 3,554,527 1/1971 [73] Assignee: Air Logistics Qorporation, Pasadena, Cahf. 3 4 35 3/1972 3,669,052 6/1972 [22] Flled. Nov. 1, 1971 13188013 5/1960 v FOREIGN PATENTS OR APPLICATIONS Related Application Data 402,450 3/1943 ltaly 114/16 R [63] Continuation-impart of Ser. No. 74,820, Sept. 23, 1,204,640 9/1970 Great Britain 114/16 R 1970, abandoned.

Primary E.\'aminerTrygve M. Blix U-S- s R, i 1 Assistant E -an iner Ga]en Barefoot [5 Int. Cl- Attorney Agent or Finn christie Parker & Hale [58] Field 01' Search 114/16 R, 219, 74 A, 74 T, 114/40,42, 151,235 B, 74 R; 241/102, DIG. 30; 293/71 R, 71 P, 1310. 2, D16. 3, 1; 37/43 [57] ABSTRACT There 15 provlded a seml-submerged cargo system for 5 References Cited the transport of cargo under ice. The system com- UNITED STATES PATENTS prises a submerged vessel having navigational and 3 43 cargo sections and a propulsion section; connected to 33 5 222 2 R a surfaced bridge, housing the crew and controls, by 5 2 H1962 Denips et g 14/735 B an ice-cutting mast. The propulsion section drives the 310331151 5/1962 Sheehanm. 114/219 Vessel under the Surface of the Although the 3,067,712 12 1962 Doerpinghaus 1 114/74T P Section is Preferably an integral P the 3,085,533 4/1963 Goryl et a1. 114/16 R e it ay e ist as a separate tug which tows or 3,179,397 4/1965 Cleeveman e181. 114/219 pushes the vessel. 3,225,731 12/1965 McCulley 1. 114/219 3,468,277 9/1969 Rosner et a1 114/42 46 Clam, 11 Drawmg Flgures PATENTED 41975 SHEET 1 BF 5 PATENTED 75 sum 2 0f 5 PMENTED 4W5 3.868.920

SHEET 3 [IF 5 1 SEMI-SUBMERGED CARGO TRANSPORT SYSTEM BACKGROUND OF THE INVENTION This is a continuation in part of my application, Ser. No. 74,820 filed Sept. 23, 1970 now abandoned.

The Arctic shores of Alaska and the outlying islands have been shown to be capable of producing large quantities of minerals and petroleum. However, as yet, no satisfactory year-round means of transporting extracted values to market has been made available.

Normally, pipe lines would have been one of the indicated means for transporting fluids or fluidizable materials. The conditions of the Arctic, however, make their construction and operation difficult, uneconomical and potentially destructive to the environment.

The north slope of Alaska in which most of the petroleum wells are located consists of a layer of slow growing vegetation, muskeg or tundra, on the surface of partially frozen soil or permafrost formed by consolidations of gravel and ice.

Any disturbance of the layer of protective vegetation exposes the permafrost to thawing during the summer. This creates deep erosion gullies that continue to increase in depth during each successive summer season. No satisfactory method has yet been presented to permit the installation of insulated or bare pipe lines in this frozen and unstable soil to carry oil at temperatures high enough to permit it to flow freely.

The use of heavily reinforced ice-breaking tankers has also been tried on an experimental basis using a water ballast. If during the trial, the tankers hull plates were destroyed by ice a disaster would have occurred had the tanker been carrying crude oil instead of water. In addition, there is no indication that a tanker would provide satisfactory yeanround means of transportation.

Thus, no truly practical means has yet been presented which would serve to transport petroleum and other mineral values from Arctic shores to consuming areas of the United States and other parts of the world.

SUMMARY OF THE INVENTION According to the present invention, there is provided a semi-submerged transport system for the safe, economical and yearround transportation of cargo under The semi-submerged transport system comprises a submerged vessel having a navigational section and a cargo section and a means to propel the vessel under the surface of the ice, this means comprising a submerged propulsion section, a surfaced bridge and an interconnecting ice-cutting mast.

The navigational section which is generally located in the bow of the vessel contains means to adjust the depth of travel and means to monitor the under-ice travel ofthe vessel. The cargo section provides a plurality of cargo compartments and contains means to adjust ballast so that the vessel may always be operated at a slight positive buoyancy.

The submerged propulsion section contains means for propelling the vessel, fuel and preferably at least a portion of the prime source of power and is preferably an integral part of the vessel.

The surface bridge contains means to monitor and control the operation of the system and quarters for the operating crew.

The interconnecting ice-cutting mast contains means for cutting narrow paths through the ice'and provides conduits between the surfaced bridge and the propulsion section.

In a preferred construction, the navigational and cargo sections are provided with resilient cushioned runners along the top surface of the vessel to permit the vessel to glide along the undersurface of the ice, and at least longitudinal upper flotation-cargo tubes and longitudinal lower cargo-ballast tubes for adjusting buoyancy to and in maintaining the vessel at a slight positive buoyancy. The cargo compartments may be longitudinal tubes and are preferably divided by flexible diaphragms which permit imcompatible cargos and ballast to be carried in the single compartment.

In addition, the vessel is provided with horizontal and vertical thrust ports in the navigational section to facilitate raising and lowering the vessel and in docking operations.

In the preferred mast construction, ice-cutting means are driven from the propulsion section and consist of a pair of adjacent shafts. On each there is mounted a plurality of parallel ice-chipping discs containing icecutting teeth which preferably intersect, in parallel relation, the vertical bisecting plane of the mast. The shafts rotate in an opposed direction, the forward peripheries of each disc rotating in outboard direction. This functions to cause the chipped ice to be forced up and aft in a direction opposed to the direction of movement of the vessel. Preferably the mast in the zone associated with the ice chipping discs are protected by a resilient or reflective covering to deflect chips of ice thrown against the mast. In addition the angle of the mast or ice-chippers relative to the vertical is from about 10 to about 45 to prevent a pitch which would tend to raise or lower force on the vessel as it advances through the ice.

In the preferred bridge construction a platform is provided to receive helicopters which attend the operating crew.

An alternate embodiment, a means for propulsion which amounts to the propulsion section, the surface bridge and interconnecting ice-cutting mast may be operated as separate attending tug, which either tows or pushes the vessel. In these embodiments, the attending tug is provided with its own navigational aids to monitor the passage of the system or the position of the vessel under the surface of the ice.

THE DRAWINGS FIG. 1 is an illustration of relative size and opera- .tional position of the semi-submerged cargo transport system of this invention.

FIG. 2 is a more detailed representation of a semisubmerged transport system of this invention illustrating the preferred angle a of the cutting blades to the vehi cle.

FIG. 3 is a detailed illustration of the thrust port system used in altering the position of the vessel.

FIG. 4 is a detailed representation of the surfaced bridge and ice-cutting mast showing the protective resilient covering for the mast.

FIG. 5 is a more detailed representation of the inclined ice-cutting mast illustrating in part its several functional operations including the detail of a reflective protective covering for the mast.

FIG. 7 is a full operational representation of the semisubmerged cargo transport system.

FIG. 8 is a representation of a towed submerged vessel and attending semi-submerged tug.

FIG. 9 is a representation of the submerged vessel and attending semi-submerged tug in pushing operation.

FIG. I is an illustration of an ice-bound service port for the semi-submerged transport system.

FIG. 11 is an illustration of the preferred runners employed to protect the vessel shown with reference to the cargo section.

DESCRIPTION According to the present invention there is provided a semi-submerged system for the safe, economical and year-round transport of cargo from ice-bound areas such as the Arctic.

This transport system comprises, generally, a fully submergible vessel having navigational and cargo sections and means to propel the vessel under the surface of the ice comprising a propulsion section connected to a surfaced bridge by a semi-submerged ice-cutting mast. While the propulsion section is preferably an integral part of the vessel, it may in the alternative, be operated as a separate attending tug which pushes or tows the vessel.

The semi-submerged transport system is adapted to be operated at the slight positive buoyancy. In this system, the navigational section located ahead of the cargo section contains means to alter the relative depth of travel of the vessel and normally contains means to monitor the path of travel under the ice.

The cargo section contains a plurality of compartments preferably containing flexible diaphragms which allow incompatible cargos or ballast to be carried in the same compartment. It is also preferably provided with a plurality of flotation-cargo tubes and cargo-ballast tubes which are used to adjust the vessel buoyancy.

At least the vessel is also provided with cushioned runners along its upper surface which permits it to meet obstructions without damage and glide along the undersurface of the ice and the mast provided with a resilient coating or reflective covering to protect the mast against ice damage.

The propulsion section contains the fuel and means of propulsion. The prime source of power generation, preferably gas turbines, are located in the propulsion section and/or the surfaced bridge.

The surfaced bridge contains means to monitor and control the operation of the transport system and provides quarters for the operating crew.

The ice-cutting mast which connects the bridge to the propulsion section also provides conduits for the transport of fuel and power between the bridge and the propulsion section and air where the prime means of power generation is in the propulsion section.

With reference now to FIG. 1, the semi-submerged cargo transport system of this invention comprises a navigational section 12, a cargo section 14 and an integral or separate propulsion section 16 which is semisubmerged and comprises a submerged propulsion section 15, a semi-submerged ice-cutting mast l8 and a surface bridge 20 above the surface of ice 22, mast 18 being provided with ice-cutting means to cut a path through the layer of ice.

. 4 With reference now to FIGS. 1, 2 and 3, the cargo section 14 of the semi-submerged transport system I0.

is elongated and has a streamlined bow 24. impactresilient runners 26, which permit the vessel to glide, when necessary, along the undersurface of the ice. The runners, preferably have foam-filled layers for shock absorption and for deflecting the bow down and out of the path of any downwardly projecting ice.

With reference to FIG. 11, in the preferred construction of the vessel the runners 26 are constructed of open celled foamed layers 27 which decrease in density in the vertical direction. The foam is covered with a porous nylon skin 29 and coated on the top with an abrasive resistant coating 31 such as a-urethane or an epoxy. The porous nylon skin permits water to enter foam cells. When the runner strikes an obstruction the contained water is released thereby absorbing the force. The abrasion resistant top coating, in turn, protects the foam and nylon skin from abrasive forces. As the foam has a density gradient resistance to compressive force will increase with compression and as energy is absorbed.

It is also provided with diving vanes 28 used to control the depth of travel in water to compensate for the variations in ice thickness. The system is also preferably provided with rear diving vanes 30 in order that a change of depth during travel may be realized without a material change in attitude.

With particular reference to FIG. 2, which reference is equally applicable to FIGS. 1, 4, 8 and 9, at least the ice chipper or cutters are preferably positioned at some angle a to the vertical and preferably from about l0 to about 45 to the vertical. Within those ranges, pitch forces induced during the cutting action of ice chippers are minimized to minimize or eliminate any tendency for the vessel to rise or lower due to cutting action.

With particular additional reference to FIG. 3, the navigational section I2 is also provided with a thrust system 32 comprising intercommunicating thrust

ports

34, 36 and 38. At least thrust ports 34 and 36 contain shaft or electric driven props 40 or water turbines. Thrust ports 34 are used in raising or lowering the vessel, particularly at low speeds. Thrust ports 36 which are horizontally oriented are used to alter the sideward motion of the vessel and are particularly useful in docking operations. Port 38 is used as a reverse thrust port to alter the forward movement of the vessel and acts as a brake. It may contain its own propeller, but preferably it contains a one-way flap or valve 42. When ports 34 and 36 are in operation in a manner which forces water towards the center of the thrust system, valve 42 opens and provides a net thrust outwardly from port 36 which opposes to the forward motion of the transport system.

Vertically oriented thrust ports 34 are most important to the operation of the vessel. As already indicated, the vessel 10 is operated at a slight positive buoyancy in order that it will not be subject to compressive forces when at rest, due to settling of the vessel. The tendency of the vessel to rise is overcome at normal operating speeds by a slight downward force vector created by a pitch in

diving vanes

28 and 30. When speed is reduced, however, the buoyant force may overcome the counteracting force porvided by the vanes and the vessel may tend to rise. This may occur, for instance, when an oppressive mass of ice is encountered which slows the vessel due to the amount of icecutting which must be accomplished. Thrust ports 34 are set into operation to provide an upward thrust to maintain the vessel at a desired depth.

Thrust ports 34 also play an important part during the launching operations. The cargo vessel may, for sundry reasons, come to rest at periods of time along the undersurface of the ice, either because of repairs, servicing of the crew, or merely loading, unloading or transfer operations. The undersurface of the ice will present an obstruction to the launching of the vessel either because of protrusions which extend into the water, or mere friction. These thrust ports, therefore, provide an instant means to force the vessel downwards when operation is to resume.

Horizontal thrust ports 36 play an important part in maneuvering the vessel during docking operations as they can be effectively used as the transport system approaches a dock or port to provide a sideward motion in order to properly mate the vessel with portside or dock facilities.

The navigational section may also be provided with elevation and depth sensors, such as sonar devices, (not shown) which automatically, or through responsive action by the monitoring crew, adjust the operation of

vanes

28 and 30 and, when necessary, thrust ports 34 and 36, to adjust the position of vessel relative to the undersurface of the ice, the floor of the seaway, or a servicing platform, vessel or port.

To monitor the passage of the system under the ice, the navigational section is also provided with TV camera 44 and lights 46.

For maximum versatility, the cargo section 14 is preferably multi-compartmented with each compartment 48 divided by a flexible diaphragm 50 which may be moved from one side of the compartment to the other by differential pressure when fluids are pumped into the compartment. This permits, for instance, a clean water ballast to be carried in one side of the diaphragm without contaminating the cargo on the other side. Ballast water may be discharged at the mooring when the cargo in the other portion of the compartment, such as petroleum, is being loaded without attendant pollution of surrounding seawater. In addition, flexible diaphragms may be used to keep incompatible liquids from mixing when mixed cargos are carried in the same compartment.

Cargo section 14 is preferably provided with a plurality of longitudinal flotation-cargo tubes 52 and ballastcargo tubes 54. These tubes may be used as containers for cargo and heavy slurry ballast when the main cargo is petroleum or another cargo lighter then seawater, or may be used as air flotation chambers when the cargo is more dense than the surrounding water.

The buoyancy of the system 10 is normally controlled by a regulated proportion of air and/or seawater in upper flotation cargo tubes 52 and ballast in lower car go-ballast tubes 54, the loading of the tubes and containers being such that the system 10 is always maintained at a slight positive buoyancy. This assures that it will come to rest at the undersurface of the ice to avoid hydraulic pressures at increased depth and permit the vessel to run on the water surface when the sea is open. The cargo compartments 48 and tubes 52 and 54 are fed through servicing ports 56, located at one or more positions on each side of the hull as well as in the bow and stern of the cargo section.

While the cargo compartments 48 may be fairly large, they may also be longitudinal tubes illustrated in FIG. 9, similar or identical to tubes 52 and 54. Preferably, they and tubes 52 and 54 are also divided by flexible diaphragms which permit incompatible cargoes to be carried in one tube. Each container and/or tube is provided with a suitable vent system which permits air and/or water displacement during loading and unloadmg.

The cargo section may carry a wide variety of prod ucts including among others, petroleum products, chemicals, gases, fluidizable minerals, slurries such as ground ores, foodstuffs and the like. They may, for instance, be used to transport raw materials from Arctic areas and return needed supplies to such areas.

Cargo section 14 may be of rigid or semi-rigid construction. Rigid construction is used for unitized construction and may be achieved through the use of steel, aluminum, fiberglass, reinforced resins and the like. Semi-rigid construction may be used when the cargo is towed. The towed vessel may employ a structure substantially as set forth in U.S. Pat. No. 3,296,994 incorporated by reference, and may, as disclosed therein, be of expandable construction. This construction is particularly useful when the cargo compartments are longitudinal tubes which can be removed or added to meet fluctuations in cargo supply.

Submerged propulsion section 16 providing propulsion means 15 is attached to ice-cutting mast 18 which is, in turn, connected to a surfaced bridge 20. The submerged portion contains the prime means of propulsion, typically twin screw propellers or a water turbine at its stern, and houses the fuel compartment; where necessary, a ballast compartment and, where desired, contains the water supply for the crew in bridge 20. The fuel and water compartments preferably are flexible diaphragms or are of bladder construction which allow the water and fuel to be supplanted by a seawater ballast as they are consumed without contamination. This allows overall buoyancy to remain fairly constant throughout operation. It is steered by rudder 57 and may have stabilizing fins 59.

The prime source of power may be gas turbines, steam generator, internal combustion engines, nuclear engines and the like, with gas turbines being preferred for simplicity of operation. Although the prime source of power generation may be housed in the submerged propulsion section 16 and/or the bridge 20, it is preferably located in the submerged propulsion section, with the air required for combustion being provided through mast 18 which also serves as the exhaust port and will be hereinafter explained.

In addition to providing the power for propulsion which is normally in excess of about 40,000 h.p., the power source also provides power to operate the icecutters which is generally in the order of 6,000 h.p., and generates the electricity for operation of the entire transport system.

When the prime source power generation is contained in the bridge, power is transmitted to the propulsion section through shafts in mast l8. Alternately, the power can be converted to electrical energy which is transmitted to motors in the propulsion section.

Surfaced bridge 20 houses crew, the operational sys- [em for monitoring and controlling the cargo systems and normally provides landing platform 58 for receiving helicopters and VTOL craft which attend to the transport system. The lower surface of bridge 20 is serves as a conduit to transport needed supplies from.

the submerged portion to the bridge and, where the prime source of power generation is located in the submerged portion of the propulsion section, air to the prime source of power generation, and a conduit for exhaust.

With reference now to FIGS. 4, and 6, there are shown in greater detail, bridge and the mast 18, which is preferably inclined, of the semi-submerged cargo system of this invention and illustrates the detail of the operation of an ice-cutting mechanism which may be used.

Bridge 20, as indicated, houses the controls system and the crew. It may also, where desired, house all or part of the prime source of energy, but will normally always house an energy source for providing the energy requirements of bridge 20. This may be a gas turbine located below the bridge and supported by mast 18 or may, where desired, be an electrical motor driven from prime energy source located in the submerged portion of propulsion section 18, and transmitted to the bridge through conduits 62 in mast 18. As indicated, bridge 20 is provided with landing deck 58 for receiving helicopters 60 or VTOL craft, which are used to serve needs of the operating crew.

In addition to a normal observation area 64 the bridge is provided with other navigational aids such as radar 66, antenna 70 and TV receiver 72, lights 74, and other navigational requirements such as fog horns and the like.

With further reference to FIGS. 4, 5 and 6, the icecutting system 76 functions to break and chip the ice in the path of the moving tug and throw ice chips outward and aft. As the aft component of the cutter action is in the direction of the propulsion forces, it aids in the forward motion of the tug.

With particular reference to FIG. 5, the mast also provides a plurality of conduits 62 which provide communication between bridge 20 and the submerged propulsion section. Fuel, power, air for combustion and exhaust may be transmitted through them depending on the construction used and the location of the source of power generation.

One conduit may, for instance, contain a ladder 78 for access to the engine room when it is located in the submerged portion section. They may also be provided with a conveyor system and lines to transport water and supplies to the bridge where the submerged section is employed for storage of crew needs. When the engines are submerged, air is drawn in an intake 80 in bridge 20 or a comparable one in mast 18. The exhaust may be ejected to the water but is preferably returned through insulated conduits to bridge 20 to provide indirect heating for the cabin. Exhaust gas may also be ducted through controllable vents to aid in stabilization.

With reference to FIGS. 4, 5 and 6, the preferred icecutting system 76 comprises shafts 82 on which there is mounted in parallel relationship, a plurality of discs 84, each disc containing a plurality of chipping teeth 86. The discs are preferably positioned such that the path of travel of the teeth of eachdisc overlapping the path of travel of the teeth mounted on the discs of the adjacent shaft but in a different parallel plane. The discs rotate in an opposed direction cutting the ice in a manner such that chippedice is thrown out and aft as a path is cut through the ice.

At regular intervals along the length of mast 18 are located load bearing ridges 88 which serve to support the shafts under the cutting loads it must sustain, and shroud 90 which covers the ice-chipping mechanism when the vessel is operated in open water.

Although the ice-chipping apparatus has been described in terms of using a cutting system comprising bladed discs whose teeth intersect a common plane, it will be appreciated that other cutting mechanisms may also be used. There may be employed, for instance, he lical intermeshing cutting blades which rotate in an opposed direction to achieve the same ice-breaking function. Alternately, there may be employed reciprocating saw-like cutters which chip and lift the broken ice away from the path of travel of the tug.

With reference to FIGS. 4, 5, and 6 whatever ice chipper or cutting mechanism is employed there exists a problem of damage to mast 18 due to chips of flying ice. To overcome this problem the port and starboard edges of mast 18 should be rounded as shown in FIGS. 4, 5 and 6 and protected by reflective cover 19 shown in FIG. 5 or coated with an elastomeric material 21 shown in FIGS. 4 and 6 to deflect the projected chips of ice.

With particular reference to FIG. 5, the reflective coating may be a glass fibre reinforced shield made of a material such as Stratoglas which is composed of strands of cross oriented glass fibres bound by a resin such as an epoxy resin, a polyester and the like. When employed as shown in FIG. 5 the sheath of the reflective covering 19 may be hollow, filled with sea water or an inner resilient material such as a foam or an elastomeric material 21. The reflective shield is secured to mast 18 only at the ends thereof with any resilient foam or elastomeric material 21, if provided, being contained between the reflective shield 19 and mast 18.

In the alternative and with particular reference to FIGS. 4 and 6, there may be employed conventional coatings of an elastomeric material 21 such as a butadiene rubber, a foamed polymer such as foamed lower olefin and vinyl polymers which have sufficient resiliency to accept and deflect the blow of ice chips without material deterioration of the elastomeric material.

It is also apparent the greatest stress will be on mast 18. It must not only bear the load of the bridge, but must bear the ice forces. It should, therefore, be of extra heavy reinforced construction. It will be appreciated, however, that since the path is narrow and the mast tapered to prevent wedging, the loads will be minimized relative to that encountered by a conventional ice-cutting cargo vessel. This also represents a minimization of the power requirements for ice breaking.

With reference to FIGS. 4 and 5, mast 18 may be provided with rudder or flap 92 which may be operated manually or by signal from a sensor such as gyroscopic readily understood with reference to FIG. 7. In operation, semi-submerged transport system 10 travels in part through and under the surface of ice 22. As illustrated, only the bridge and a portion of mast 18 are surfaced. The submerged portions travel freely in the water and they are not subject to wave actions, ice flows or the like. As indicated, and on a relative basis, mast 18 is narrow and as a consequence the amount of ice which must be cut to establish a path through ice 22 is small. In addition, since the mast is tapered in a rearwardly direction there is little opportunity for jamming.

Virtually all that really is exposed is bridge 20 which presents, in a war-time situation, s small and inconspicuous target. In contrast, war-time vulnerability of tankers and pipelines would be extremely high. Further, the system is not vulnerable to ice flow compression damage as ice is continuously being cut away. This eliminates pollution which would be caused by damage to a conventional type system.

The system also does not have to compensate for side drags imposed by winds and currents which provide the further benefit in reduced power and overall operating costs.

As major corrosion and scraping damage to icebreaking tankers would occur at water-air interface, maintenance problems on a relative basis are substantially reduced. As only a portion of the system is at the interface, it functions to cut a path through the ice to minimize abrasion.

FIG. 8 represents one alternative embodiment of this invention. In substance, the propulsion section 16 which remains submerged and attached to mast l8 and bridge 20 are separated from cargo section 16 to function as an attending tug to tow the vessel through urnbilical cord tow line 96 which services the power re quirements of the navigational aids contained in the towed navigational section 12. As the cargo section 14 must still be provided with some manipulative operations to adjust in depth and provide reduced thrust, most of the nagivational aids provided in the unitized construction are retained by navigational section 12, namely, the diving vanes, thrust ports and sensory mechanisms which are used to sense and control depth through operation of diving vanes and thrust ports. The TV camera and lights for monitoring the forward motion of the system may be eliminated and provided, as shown, in the attending propulsion section 16.

This system functions in the same manner as the unitized construction but some additional care must be taken during transport. For instance, should unusual ice conditions reach such that the ice-cutting system becomes overloaded, the forward direction of the at tending tug may be slowed considerably. In this instance, umbilical cord 96 will become slack. The cargo vessel having a slight positive buoyancy will tend to rise to come to rest at the underside of the ice. If excessive inertia exists, thrust may be applied through port 34 in a downward direction and a reverse thrust through port 38 in conjunction with the operation of

vanes

28 and 30 to direct the vessel towards the ice surface. As the cargo vessel is suitably protected with cushions it will, upon reaching the surface, lose much of its inertia as a consequence of the frictional effect of being brought into contact with the ice.

Another embodiment is illustrated in FIG. 9 in which the tug and cargo vessel are shown in separated relationship for a more detailed explanation of the additional equipment which would be used for such an operation.

Attending tug will have, as shown, a more blunt bow 98 to mate with a corresponding section at the stern on cargo section 14. Attending tug 36 will also be provided with a series of coupling hooks 100 which serve to couple and engage with cargo vessel 10. One of the hooks 102 is connected to a retractable cable 104 to meet the situation where forward motion of the tug is resisted. The cargo vessel will be released and cable 104 will then be played out with the cargo vessel until it loses its inertia. Once the ice jam has been overcome, the tug may then advance to the cargo vessel by winding cable 104 and recoupling to it. During a released position, the tug must be capable of monitoring the position of the cargo vessel. It is, therefore, provided with TV camera 106 and lights 108 in order to observe the position of cargo vessel 10 under the surface of the ice.

Since the cargo vessel is the forwardmost object in the travel of the transport system it is also provided with TV camera 44 and lights 46 which monitor its forward motion under the surface of the ice. These as well as the electric motors required for the operation of vanes and thrust ports are energized by electrical conduit connections in the stern of cargo vessel which connect with mating connections 110 in the how 98 of propulsion section 16.

These connections may, for instance, consist of a series of annular conductors separated by an elastomeric material. They are cone-shaped and compress upon mating with corresponding cone-shaped connectors on the cargo vessel, the water-tight electrical connections being complete upon full compression.

FIG. 10 is an illustration of a servicing operation which can be used for loading and unloading of the semi-submerged cargo system in icebound areas, With reference thereto, there is illustrated a servicing port 112 having a master control cabin 114 and generally providing a landing pad 116 for attending helicopters. The control cabin 114 is mounted on pedestal 118 which, in turn, is secured or anchored to the floor of the seaway. It is provided with pipeline communication to the shore for the loading and discharge of cargos. To protect service module 112 there is also provided icecutting systems 120 which serve to cut any ice flows which may tend to damage or topple service module 112. As is shown, while one cargo vessel is being serviced, namely, either loaded or unloaded through service port 56, a towed cargo vessel is advanced to the service port.

This demonstrates an advantage of the cargo transport system of employing a separate propulsion vessel, namely, that one tug may service a number of vessels. As one is being emptied or filled, it may at one point, say, an icebound service port, be used to return carrying a full vessel to a landside port or some point in an open water zone where the cargo vessel may be towed to a landside port by a surface vessel. It may then, in exchange, receive an empty vessel or a vessel loaded with cargo intended to be transported to the icebound area by transport under the ice. Upon reaching the service module 112 where the returned vessel is unloaded and loaded, the tug picks up an already loaded cargo vessel for return to landside or ice-free port.

What is claimed is:

I. A transport system for the transportation of cargo under the surface of the ice which comprises:

1 1 a. a submergible cargo vessel comprising:

i. a navigational section containing means to adjust the depth of travel of said vessel; ii. a cargo section containing a plurality of compartments for the storage of cargo, means to load said cargo compartments and means to maintainthe vessel at a slight positive buoyancy during transit;

b. means to propel said vessel, said means containing the prime source of power and comprising:

i. a submergible propulsion section;

ii. a surfaced bridge containing at least means to monitor and control the operation of the transport system and quarters for the operating crew;

iii. a mast rigidly connected to said propulsion section and said surfaced bridge, said mast containing forwardly positioned powered ice cutting means movably mounted on said mast to chop ice into chips and form a path through ice which is at least coextensive with the width of said mast, at least said ice cutting means being at an angle of from about to about 45 to the vertical in the bow direction to eliminate a pitch force due to the ice chopping function of said powered ice cutting means.

2. A transport system as claimed in claim 1 in which the means for propelling said cargo vessel is an integral part of said cargo vessel.

3. A transportation system as claimed in claim 1 in which the means to propel said cargo vessel is detachable from said cargo vessel.

4. A transportation system as claimed in claim I in which. said cargo vessel contains within the cargo section a plurality of upper longitudinal flotation cargo tubes adapted for increasing buoyancy and lower longitudinal cargo-ballast tubes for decreasing buoyancy, to maintain the cargo section at a positive buoyancy said upper longitudinal flotation cargo tubes being above and said lower longitudinal cargo-ballast tubes being below said plurality of compartments for the storage of cargo.

5. A transportation system as claimed in claim 1 in which the cargo compartments are divided by flexible diaphragms.

6. A transportation system as claimed in claim 5 in which the cargo compartments comprise a plurality of longitudinally disposed tubes.

7. A transportation system as claimed in claim 1 in which the cargo vessel is provided with at least one resilient, shock absorbing runner extending longitudinally along at least a portion of the upper surface thereof.

8. A semi-submerged transport system as claimed in claim 7 in which the shock absorbing runner comprises a foam core which decreases in density in a vertical direction.

9. A transportation vessel as claimed in claim 1 in which the means to alter the depth of said cargo vessel include:

a. at least one set of diving vanes, and

b. at least one vertically disposed thrust port connecting the lower and upper surfaces of said navigation section, said thrust port containing means to induce a flow of water through said port.

10. A transportation system as claimed in claim 9 in combination with a horizontally disposed thrust port extending from one side of said navigational section to the opposed side thereof, said horizontally disposed thrust port intersecting said vertically disposed thrust port and'containing means to inducea flow of water therethrough and a longitudinally-thrust port extending from the bow of said navigational section and communicating with the intersection of said vertically disposed thrust port and said horizontally disposed thrust port.

11. A transportation system as claimed in claim 1 in which the ice-cutting means includes a pair of vertically disposed shafts, each shaft containing a plurality of icechipping discs, the said shafts adapted to rotate in an opposed direction, the forward peripheries of each disc rotating in an outboard direction.

12. A transportation system as claimed in claim 1 in which at least a portion of the prime source of power is contained in said normally submerged propulsion section.

13. A transportation system as claimed in claim 12 in which the prime sources of power are gas turbines.

14. A transportation system as claimed in claim 1, in which the rigidly connecting mast is provided with an ice chip deflecting protective cover which is a reflective cover or an elastomeric coating.

15. A transportation system as claimed in claim 14 in which the reflective cover comprises a glass fiber reinforced resin.

16. A submergible cargo vessel for the transporting of cargo under the surface of the ice which comprises:

a. a navigational section positioned in the bow of said cargo vessel and to adjust the depth of travel of said vessel;

b. a cargo section containing a plurality of compartments for the storage of cargo, means to load said cargo compartments and means to maintain the vessel at a slight positive buoyancy during transit, said cargo vessel having longitudinally disposed along the upper surface thereof at least one longitudinally extending resilient runner having:

i. an open cell flexible foam core which decreases in density in a vertical direction;

ii. a flexible permeable web securing said core to the upper surface of said cargo vessel;

iii. an abrasion resistant flexible coating on the upper surface of said retaining web.

17. A submergible cargo vessel as claimed in claim 16 in which said cargo section contains a plurality of upper longitudinal flotation cargo tubes adapted for increasing buoyancy and lower longitudinal cargo-ballast tubes for decreasing buoyancy.

18. A submergible cargo vessel as claimed in claim 16 in which the cargo compartments are divided by flexible diaphragms.

19. A submergible cargo vessel as claimed in claim 16 in which the cargo compartments are longitudinal tubes.

20. A submergible cargo vessel as claimed in claim 16 in which the means to alter the depth of said cargo vessel include:

a. at least one set of diving vanes and b. at least one vertically disposed thrust port connecting the lower and upper surfaces of said navigation section, said thrust port containing meansto induce a flow of water through said port.

21. A submergible cargo system as claimed in claim 20 in combination with a horizontally disposed thrust port extending from one side of said navigational section to the opposed side thereof, said horizontally disposed thrust port intersecting said vertically disposed thrust port and containing means to induce a flow of water therethrough and a longitudinally thrust port extending from the bow of said navigation section and communicating with the intersection of said vertically disposed thrust port and said horizontally disposed thrust port.

22. A semi-submerged transport system for the transportation of cargo under the surface of ice which comprises:

a. a submergible cargo vessel comprising:

i. a navigational section containing means to adjust the depth of travel of said cargo vessel, said means including at least one set of diving vanes and at least one vertically disposed thrust port connecting the lower and upper surfaces of said navigational section, said thrust port containing means to induce a flow of water through said thrust port;

ii. a cargo section containing a plurality of compartments for the storage of cargo, means to load said cargo compartments and means to maintain the cargo vessel at a slight positive buoyancy during transit;

b, means to propel said cargo vessel, said means containing the prime source of power and comprising:

i. a submergible propulsion section;

iii. a mast rigidly connected to said propulsion section and said surfaced bridge, said mast containing fowardly positioned powered ice cutting means movably mounted on said mast to chop ice into chips and form a path through ice which is at least coextensive with the width of said mast, at least said ice cutting means being at an angle of from about to about 45 to the vertical in the bow direction to eliminate a pitch force due to the ice chopping function of said powered ice cutting means.

23. A semi-submerged transport system as claimed in claim 22 in which the means to adjust the depth of travel contained in the navigational section includes a horizontally disposed thrust port extending from one side of said navigational section to the opposed side thereof, said horizontally disposed thrust port intersecting said vertically disposed thrust port and containing means to induce a flow of water therethrough and a longitudinally thrust port extending from the bow of said navigation section and communicating with the intersection of said vertically disposed thrust port and said horizontally disposed thrust port.

24. A semi-submerged transport system as claimed in claim 22 in which the mast is protected against projected ice chips by a reflective cover or an elastomeric coating.

25. A semi-submerged transport system as claimed in claim 24 in which the reflective cover comprises a glass fiber reinforced resin.

26. A semi-submerged tug for propelling a submerged vessel under ice which comprises:

a. a submergible propulsion section including means to couple with said submerged vessel;

b. a surfaced bridge containing at least means to monitor the position of said submerged vessel,

means to control the operation of said tug and quarters for the operating crew;

c. a mast rigidly connected to said propulsion section and said surfaced bridge, said mast containing forwardly positioned powered ice cutting means movably mounted on said mast to chop ice into chips and form a path through ice which is at least coextensive with the width of said mast, at least said ice cutting means being at an angle of from about 10 to about 45 to the vertical in the bow direction to eliminate a pitch force due to the ice chopping function of said powered ice cutting means and said tug containing a prime means of power to propel a submerbed vessel under ice.

27. A semi-submerged tug as claimed in claim 26 in which at least part of the prime means of power is contained in the propulsion section.

28. A semi-submerged tug as claimed in claim 27 in which the prime sources of power are gas turbines.

29. A semi-submerged tug as claimed in claim 26 in which the ice-cutting means includes a pair of vertically disposed shafts each shaft containing a plurality of icechipping discs, the said shafts adapted to rotate in an opposed direction, the forward peripheries of each disc rotating in an outboard direction.

30. A semi-submerged tug as claimed in claim 26 in which the mast is protected against chips of ice by a re flective protective cover or elastomeric coating.

31. A semi-submerged tug as claimed in claim 30 in which the reflective protective cover comprises a glass fiber reinforced resin.

32. A transport system for the transportation of cargo under the surface of the ice which comprises:

A. a submergible cargo vessel comprising:

i. a navigational section containing means to adjust the depth of travel of said vessel;

ii. a cargo section containing a plurality of compartments for the storage of cargo, means to load said cargo compartments and means to maintain the vessel at a slight positive buoyancy during transit, said cargo vessel having longitudinally disposed along the upper surface thereof at least one longitudinally extending resilient runner having:

a. an open cell flexible foam core which decreases in density in a vertical direction;

b. a flexible permeable web securing said core to the upper surface of said cargo vessel;

c. an abrasion resistant flexible coating on the upper surface of said retaining web,

i. a submergible propulsion section;

iii. a mast rigidly connected to said propulsion sec tion and said surfaced bridge, said mast containing forwardly positioned powered ice cutting means movably mounted on said mast to chop ice into chips and form a path through ice which is at least coextensive with the width of said mast.

33. A transport system as claimed in claim 32 in which the means for propelling said cargo vessel is an integral part of said cargo vessel.-

15 34. A transportation system as claimed in claim 32 in which the means to propel said cargo vessel is detachable from said cargo vessel.

35. A transport system for the transportation of cargo under the surface of the ice which comprises:

a. a submergible cargo vessel comprising:

ii. a cargo section containing a plurality of compartments for the storage of cargo, means to load said cargo compartments and means to maintain the vessel at a slight positive buoyancy during transit;

b. means to propel said vessel, said means containing the prime source of power and comprising;

i. a submergible porpulsion section;

iii. a mast rigidly connected to said propulsion section and said surfaced bridge, said mast containing forwardly positioned powered ice cutting means including a pair of inclined vertically disposed shafts, each shaft containing a plurality of ice chipping discs, the said shafts adapted to rotate in an opposed direction, the forward peripheries of each disc rotating in an outboard direction to chop ice into chips and expel said ice chips to form a path through ice which is at least coextensive with the width of said mast.

36. A transport system as claimed in claim 35 in which the inclined vertically disposed shafts are disposed at an angle of from about to about 45 degrees to the vertical in the bow direction to eliminate a pitch force due to the ice chopping function of said powered ice cutting means.

37. A semi-submerged transport system as claimed in claim 35 in which the mast is protected against chips of ice by a reflective protective cover or an elastomeric coating.

38. A semi-submerged transport system as claimed in claim 37 in which the reflective protective cover comprises a glass fiber reinforced resin.

39. A semi-submerged transport system for the transportation of cargo under the surface of ice which comprises:

a. a submergible cargo vessel comprising:

i. a navigational section containing means to adjust the depth of travel of said cargo vessel, said means including at least one set of diving vanes and at least one vertically disposed thrust port connecting the lower and upper surfaces of said navigational section, said thrust port containing means to induce a flow of water through said thrust port; a cargo section containing a plurality of compartments for the storage of cargo, means to load said cargo compartments and meant to maintain the cargo vessel at a slight positive buoyancy during transit;

b. means to propel said cargo vessel, said means containing the prime source of power and comprising: i. a submergible propulsion section; ii. a surfaced bridge containing at least means to monitor and control the operation of the transport system and quarters for the operating crew;

iii. a mast rigididly connectedto said propulsion section and said surfaced bridge, said mast containing forwardly positioned powered ice cutting means including a pair of inclined vertically disposed shafts, each shaft containing a plurality of ice chipping discs, the said shafts adapted to rotate in a opposed direction, the forward peripheries of each disc rotating in an outboard direction to chop ice into chips and expel said ice chips to form a path through ice which is at least coextensive with the width of said mast.

40. A semi-submerged transport system as claimed in claim 39 in which the forwardly positioned means to cut a path through ice is disposed at an angle from about 10 to about 45 to the vertical in the bow direction to eliminate a pitch force due to the ice chopping function of said powered ice cutting means.

41. A semi-submerged transport system as claimed in claim 39 in which the mast is protected against projected ice chips by a reflective cover or an elastomeric coating.

42. A semi-submerged tug for propelling a submerged vessel under ice which comprises:

b. a surfaced bridge containing at least means to monitor the position of said submerged vessel, means to control the operation of said tug and quarters for the operating crew;

c. a mast rigidly connected to said propulsion section and said surfaced bridge, said mast containing forwardly positioned powered ice cutting means including a pair of inclined vertically disposed shafts, each shaft containing a plurality of ice chipping discs, the said shafts adapted to rotate in an op posed direction, the forward peripheries of each disc rotating in an outboard direction to chop ice into chips and expel said ice chips to form a path through ice which is at least coextensive with the width of said mast.

43. A semi-submerged tug as claimed in claim 42 in which the mast is protected against chips of ice by a reflective protective cover or elastomeric coating.

44. A semi-submerged tug as claimed in claim 42 in which the forwardly positioned means to cut a path through ice is disposed at an angle of from about 10 to about 45 to the horizontal in the bow direction to eliminate a pitch force due to the ice chopping function of said powered ice cutting means.

45. A semi-submerged tug as claimed in claim 44 in which the mast is protected against chips of ice by a reflective protective cover or elastomeric coating.

46. A semi-submerged tug as claimed in claim 45 in which the reflective protective cover comprises a glass fiber reinforced resin.

"H050 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION atent NO- 3,868,920 Dated March 4, 1975 Inventor) Joseph F. Schirtzinger It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, line 64, "porvided" should read -provided.

Column 9, line 13, "5" should read a-.

Column 15, line 58, "meant" should read means-.

Column 16, line 12, "a" should read an--.

Signed and sealed this 10th day of June 1975.

(SEAL) Attest:

C. MARSHALL DANN RUTH C. MASON Commissioner of Patents Attesting Officer and Trademarks

Claims

1. A transport system for the transportation of cargo under the surface of the ice which comprises: a. a submergible cargo vessel comprising: i. a navigational section containing means to adjust the depth of travel of said vessel; ii. a cargo section containing a plurality of compartments for the storage of cargo, means to load said cargo compartments and means to maintain the vessel at a slight positive buoyancy during transit; b. means to propel said vessel, said means containing the prime source of power and comprising: i. a submergible propulsion section; ii. a surfaced bridge containing at least means to monitor and control the operation of the transport system and quarters for the operating crew; iii. a mast rigidly connected to said propulsion section and said surfaced bridge, said mast containing forwardly positioned powered ice cutting means movably mounted on said mast to chop ice into chips and form a path through ice which is at least coextensive with the width of said mast, at least said ice cutting means being at an angle of from about 10* to about 45* to the vertical in the bow direction to eliminate a pitch force due to the ice chopping function of said powered ice cutting means.

4. A transportation system as claimed in claim 1 in which said cargo vessel contains within the cargo section a plurality of upper longitudinal flotation cargo tubes adapted for increasing buoyancy and lower longitudinal cargo-ballast tubes for decreasing buoyancy, to maintain the cargo section at a positive buoyancy said upper longitudinal flotation cargo tubes being above and said lower longitudinal cargo-ballast tubes being below said plurality of compartments for the storage of cargo.

9. A transportation vessel as claimed in claim 1 in which the means to alter the depth of said cargo vessel include: a. at least one set of diving vanes, and b. at least one vertically disposed thrust port connecting the lower and upper surfaces of said navigation section, said thrust port containing means to induce a flow of water through said port.

10. A transportation system as claimed in claim 9 in combination with a horizontally disposed thrust port extending from one side of said navigational section to the opposed side thereof, said horizontally disposed thrust port intersecting said vertically disposed thrust port and containing means to induce a flow of water therethrough and a longitudinally thrust port extending from the bow of said navigational section and communicating with the intersection of said vertically disposed thrust port and said horizontally disposed thrust port.

11. A transportation system as claimed in claim 1 in which the ice-cutting means includes a pair of vertically disposed shafts, each shaft containing a plurality of ice-chipping discs, the said shafts adapted to rotate in an opposed direction, the forward peripheries of each disc rotating in an outboard direction.

16. A submergible cargo vessel for the transporTing of cargo under the surface of the ice which comprises: a. a navigational section positioned in the bow of said cargo vessel and to adjust the depth of travel of said vessel; b. a cargo section containing a plurality of compartments for the storage of cargo, means to load said cargo compartments and means to maintain the vessel at a slight positive buoyancy during transit, said cargo vessel having longitudinally disposed along the upper surface thereof at least one longitudinally extending resilient runner having: i. an open cell flexible foam core which decreases in density in a vertical direction; ii. a flexible permeable web securing said core to the upper surface of said cargo vessel; iii. an abrasion resistant flexible coating on the upper surface of said retaining web.

20. A submergible cargo vessel as claimed in claim 16 in which the means to alter the depth of said cargo vessel include: a. at least one set of diving vanes and b. at least one vertically disposed thrust port connecting the lower and upper surfaces of said navigation section, said thrust port containing means to induce a flow of water through said port.

22. A semi-submerged transport system for the transportation of cargo under the surface of ice which comprises: a. a submergible cargo vessel comprising: i. a navigational section containing means to adjust the depth of travel of said cargo vessel, said means including at least one set of diving vanes and at least one vertically disposed thrust port connecting the lower and upper surfaces of said navigational section, said thrust port containing means to induce a flow of water through said thrust port; ii. a cargo section containing a plurality of compartments for the storage of cargo, means to load said cargo compartments and means to maintain the cargo vessel at a slight positive buoyancy during transit; b. means to propel said cargo vessel, said means containing the prime source of power and comprising: i. a submergible propulsion section; ii. a surfaced bridge containing at least means to monitor and control the operation of the transport system and quarters for the operating crew; iii. a mast rigidly connected to said propulsion section and said surfaced bridge, said mast containing fowardly positioned powered ice cutting means movably mounted on said mast to chop ice into chips and form a path through ice which is at least coextensive with the width of said mast, at least said ice cutting means being at an angle of from about 10* to about 45* to the vertical in the bow direction to eliminate a pitch force due to the ice chopping function of said powered ice cutting means.

26. A semi-submerged tug for propelling a submerged vessel under ice which comprises: a. a submergible propulsion section including means to couple with said submerged vessel; b. a surfaced bridge containing at least means to monitor the position of said submerged vessel, means to control the operation of said tug and quarters for the operating crew; c. a mast rigidly connected to said propulsion section and said surfaced bridge, said mast containing forwardly positioned powered ice cutting means movably mounted on said mast to chop ice into chips and form a path through ice which is at least coextensive with the width of said mast, at least said ice cutting means being at an angle of from about 10* to about 45* to the vertical in the bow direction to eliminate a pitch force due to the ice chopping function of said powered ice cutting means and said tug containing a prime means of power to propel a submerbed vessel under ice.

29. A semi-submerged tug as claimed in claim 26 in which the ice-cutting means includes a pair of vertically disposed shafts each shaft containing a plurality of ice-chipping discs, the said shafts adapted to rotate in an opposed direction, the forward peripheries of each disc rotating in an outboard direction.

30. A semi-submerged tug as claimed in claim 26 in which the mast is protected against chips of ice by a reflective protective cover or elastomeric coating.

32. A transport system for the transportation of cargo under the surface of the ice which comprises: A. a submergible cargo vessel comprising: i. a navigational section containing means to adjust the depth of travel of said vessel; ii. a cargo section containing a plurality of compartments for the storage of cargo, means to load said cargo compartments and means to maintain the vessel at a slight positive buoyancy during transit, said cargo vessel having longitudinally disposed along the upper surface thereof at least one longitudinally extending resilient runner having: a. an open cell flexible foam core which decreases in density in a vertical direction; b. a flexible permeable web securing said core to the upper surface of said cargo vessel; c. an abrasion resistant flexible coating on the upper surface of said retaining web, B. means to propel said vessel, said means containing the prime source of power and comprising: i. a submergible propulsion section; ii. a surfaced bridge containing at least means to monitor and control the operation of the transport system and quarters for the operating crew; iii. a mast rigidly connected to said propulsion section and said surfaced bridge, said mast containing forwardly positioned powered ice cutting means movably mounted on said mast to chop ice into chips and form a path through ice which is at least coextensive with the width of said mast.

33. A transport system as claimed in claiM 32 in which the means for propelling said cargo vessel is an integral part of said cargo vessel.

34. A transportation system as claimed in claim 32 in which the means to propel said cargo vessel is detachable from said cargo vessel.

35. A transport system for the transportation of cargo under the surface of the ice which comprises: a. a submergible cargo vessel comprising: i. a navigational section containing means to adjust the depth of travel of said vessel; ii. a cargo section containing a plurality of compartments for the storage of cargo, means to load said cargo compartments and means to maintain the vessel at a slight positive buoyancy during transit; b. means to propel said vessel, said means containing the prime source of power and comprising; i. a submergible porpulsion section; ii. a surfaced bridge containing at least means to monitor and control the operation of the transport system and quarters for the operating crew; iii. a mast rigidly connected to said propulsion section and said surfaced bridge, said mast containing forwardly positioned powered ice cutting means including a pair of inclined vertically disposed shafts, each shaft containing a plurality of ice chipping discs, the said shafts adapted to rotate in an opposed direction, the forward peripheries of each disc rotating in an outboard direction to chop ice into chips and expel said ice chips to form a path through ice which is at least coextensive with the width of said mast.

36. A transport system as claimed in claim 35 in which the inclined vertically disposed shafts are disposed at an angle of from about 10 to about 45 degrees to the vertical in the bow direction to eliminate a pitch force due to the ice chopping function of said powered ice cutting means.

39. A semi-submerged transport system for the transportation of cargo under the surface of ice which comprises: a. a submergible cargo vessel comprising: i. a navigational section containing means to adjust the depth of travel of said cargo vessel, said means including at least one set of diving vanes and at least one vertically disposed thrust port connecting the lower and upper surfaces of said navigational section, said thrust port containing means to induce a flow of water through said thrust port; ii. a cargo section containing a plurality of compartments for the storage of cargo, means to load said cargo compartments and meant to maintain the cargo vessel at a slight positive buoyancy during transit; b. means to propel said cargo vessel, said means containing the prime source of power and comprising: i. a submergible propulsion section; ii. a surfaced bridge containing at least means to monitor and control the operation of the transport system and quarters for the operating crew; iii. a mast rigididly connected to said propulsion section and said surfaced bridge, said mast containing forwardly positioned powered ice cutting means including a pair of inclined vertically disposed shafts, each shaft containing a plurality of ice chipping discs, the said shafts adapted to rotate in a opposed direction, the forward peripheries of each disc rotating in an outboard direction to chop ice into chips and expel said ice chips to form a path through ice which is at least coextensive with the width of said mast.

40. A semi-submerged transport system as claimed in claim 39 in which the forwardly positioned means to cut a path through ice is disposed at an angle from about 10* to about 45* to the vertical in the bow direction to eliminate a pitch force due to the ice chopping function of said powered ice cutting meaNs.

42. A semi-submerged tug for propelling a submerged vessel under ice which comprises: a. a submergible propulsion section including means to couple with said submerged vessel; b. a surfaced bridge containing at least means to monitor the position of said submerged vessel, means to control the operation of said tug and quarters for the operating crew; c. a mast rigidly connected to said propulsion section and said surfaced bridge, said mast containing forwardly positioned powered ice cutting means including a pair of inclined vertically disposed shafts, each shaft containing a plurality of ice chipping discs, the said shafts adapted to rotate in an opposed direction, the forward peripheries of each disc rotating in an outboard direction to chop ice into chips and expel said ice chips to form a path through ice which is at least coextensive with the width of said mast.

44. A semi-submerged tug as claimed in claim 42 in which the forwardly positioned means to cut a path through ice is disposed at an angle of from about 10* to about 45* to the horizontal in the bow direction to eliminate a pitch force due to the ice chopping function of said powered ice cutting means.