Patent Publication Number: US-3878804-A

Title: Ice-breaking apparatus

Description:
iinited @tates Patent 1191 Legerer Apr. 22, 1975 [54] HQE-BREAKING APPARATUS 3,670.681 6/1972 Upchurch, Jr. 114/40 3. t 2 [76] Inventor: Friedrich J. Legerer, 90 678 7/1972 Bennett Cub l&#39;dC s.,St.Jh, y z t O n 8 Primary E.\ummerTrygve M. Bhx Assistant Examiner-Sherman D. Basinger Flledl 1973 Attorney, Agent, or Firm-Stanley E. Johnson [21] Appl. No.: 422,517  
  [57] ABSTRACT [30] Foreign Application Priority Data Method and apparatus for forming slits in ice to facili- Dec. 19,1972 Canada 159448 We the ice-breaking Operation by dragging a hose over the surface of the ice and directing jets of a 52 us. ca. 114/40 heated medium against the cmacted surface of the 51 hit. Cl. B63b 35/08 The hose is drawn Over the ice by for example 58 Field of Search 114/40-42; vessel having a beam cantilevered forwardly 61 R; 37/12 from. One or more flexible hoses having nozzles therein are suspended from the beam and jets of steam [56] References Cited from the nozzles are directed onto the ice. The flexi- UNITED STATES PATENTS bility of the hoses allows the same to follow varying contours and irregularities in the ice surface. 588,393 8/1897 Brown ll4/42 1 722,843 7/1929 Fasul 37/12 16 Claims, 8 Drawing Figures ICE-BREAKING APPARATUS This invention relates to improved apparatus for use on water-going vessels to weaken ice forwardly of the vessel during travelling and to vessels incorporating such apparatus.  
  The invention generally deals with the problem caused by the variability of ice properties as they are encountered by ice-navigating vessels which may be ice breakers, ice-strengthened freigliters. supply ships or ice-navigating ferries. In areas close to shorelines and in harbour regions. there is closed fast ice cover while on the open sea and some Arctic waters. densely floating ice floes of various sizes are predominant. The inter-action of ship and closed fast ice is that the vessel proceeds forwardly continuously as long as the ice properties permit breaking the ice by bending the ice sheet until fracture occurs. At increasing ice resistance. a combination of crushing (forming radial crack pat terns) and of bending (which exhibits circumferential crack patterns) takes place. With further increased ice resistance. the vessel resorts to ramming. that is. backing up for a considerable distance. then accelerating forwardly gaining speed and ramming the ice. Crushing occurs from such ramming and the bow rides up on top of the ice breaking it by the weight of the vessel. The capability of continuous forward movement depends mainly on the thrust. that is. the capacity of the power plant of the vessel while ramming capability is limited by the weight of the vessel.  
  The characteristics of ice vary considerably. Fast ice may be fresh. hard ice or free frozen slush with a core with or without snow cover. exhibiting properties generally of composite materials. The thickness of ice encountered by a vessel is not always uniform as pressure ridges may be built up by wind-driven ice sheets impinging on each other wherein they pile up and freeze together. Another form is known as rafted ice which originates when overlapping ice sheets freeze together. It is. thus. readily apparent ice-breaking vessels must encounter substantially varying conditions of ice and the vessel must be designed to operate at maximum resistance of ice which it is expected to encounter. This generally results in an over-design for most operational conditions.  
  Proposals have been made to add additional equipment to an ice-breaking vessel to handle severe icebreaking problems. One proposal is exemplified by US. Pat. No. 3.678.873. issued July 25. I972 to the Sun Oil Company. wherein apparatus is provided for directing a high velocity liquid against the ice mass for cutting the ice mass in a generally vertical plane prior to contact of the ice by the front of the vessel. In another proposal by the USSR. reported in the publication New Scientist. Mar. 13. 1969 at page 574. there is incorporated a driven saw mounted on the forward end of the vessel and which cuts the ice from its lower surface. Both the use of a saw as proposed by the USSR. operating on the lower surface of the ice and a high jet of liquid on the upper surface as proposed in the aforementioned US. patent are generally unsatisfactory basically because of each proposal requiring rigid structure for mounting the same on the vessel and pitching of the vessel which occurs during use in breaking up the ice. In conditions of pitching and/or varying ice thickness. the rigid structure. if too close to the ice. will become damaged or. on the other hand. placed at a safe position. in many instances. is too far from the ice to be effective.  
  Accordingly. it is a principal object of the present invention to provide apparatus effective in weakening a critical area of the ice to be fractured at a position forwardly of the vessel. This is accomplished by directing one or more jets of a heating medium onto the ice from one or more dispensing members dragged over the surface of the ice. The dispensing members preferably consist of flexible hoses having nozzles therein and/or flexibly linked tubes.  
  Accordingly. there is provided. in accordance with one aspect of the present invention a method of breaking ice in the path of travel ofa vessel comprising drag ging at least one hose in contact with the ice forwardly of the vessel during forward movement ofthe same and directing jets of a heating medium from the hose against the contacted area of the ice.  
  In accordance with a further aspect of the present invention. there is provided apparatus for forming at least one split in an ice mass in the path of travel of a vessel comprising at least one flexible hose having a plurality of nozzles in series along a portion of the length thereof and means for suspending each such hose and dragging the same over the ice surface forwardly of the vessel during forward movement of the same.  
  The invention is illustrated by way of example in reference to the accompanying drawings. wherein:  
  FIG. I is a side elevational view of the prow of a vessel having apparatus mounted thereon in accordance with the present invention:  
  FIG. 2 is a top plan view of FIG. I but including additional flexible dispensing hoses spaced laterally with reference to the length of the vessel on opposite sides of the central hose:  
  FIG. 3 is similar to FIG. 2 but illustrating the laterally positioned hoses in a different location thus effecting manoeuverability of the vessel;  
  FIG. 4 is similar to FIG. 2 but showing a different position for the apparatus;  
  FIG. 5 is a cross-sectional view of a portion of one form of flexible hose:  
  FIG. 6 is a sectional view taken along section 6-6 of FIG. 5;  
  FIG. 7 is a partial cross-sectional view of a modified dispensing flexible link hose for the heated medium; and  
  FIG. 8 is a plan view of the linked hose element shown in FIG. 7.  
  Referring now in detail to the drawings. there is illustrated the prow ofa vessel 10 proceeding forwardly (to the right as viewed in FIG. 1) through water 11 covered with a layer of ice 12. A beam 13 is pivotally mounted at 14 on the vessel and cantilevered forwardly therefrom. The beam 13 is held in position by a line 15 which may be wound onto and paid out from a reel winch mechanism 16 mounted on the deck of the vessel. By such an arrangement. or alternatively. utilizing a hydraulic piston cylinder assembly. the beam may be pivoted about pin 14 to raise and lower the free end of the same. as may be desired. The pivot pin 14 is secured in a bracket 17 mounted. if so desired. by a plate 18 for rotation about a vertical axis and which may be driven by electric motor 19 having a gear 20 engaging a gear secured to the plate. Such mounting permits swinging the cantilevered beam 13, if desired. improving manoeuverability of the vessel as will be seen hereinafter.  
  Extending longitudinally along the beam 13 is a conduit 21 which may be considered a header or manifold to supply a heated medium to further conduits to be described hereinafter. The conduit 21 may be an insulated conduit. or altermttively. located in an insulated. closed-in structure of the beam. The conduit 21 is connected by a flexible coupling 22 and further conduit 23 to a steam generator 24 carried by the vessel. Alternatively. the flexible coupling 22 may be replaced by a swivel coupling in the mounting bracket 17.  
  Connected to the conduit 21 and depending downwardly from the beam 13 is a flexible hose 25 having sufficient length as to be dragged over the surface of the ice 12 along a line corresponding to the longitudinal axis of the vessel and preceding immediately the bow of the vessel. The flexible hose 25 may be connected to the header conduit 21 through a remotely controlled valve 26 for controlling flow of the heated medium to the flexible conduit.  
  One or more feeder hoses 27 (three being illustrated in FIG. 1 are connected respectively at opposite ends to the header conduit 21 and the flexible hose 25. The feeder hoses 27 may be connected to the conduit 21, if desired. through remotely controlled valves 28 and such hoses provide additional means for supplying a heated medium to the conduit 25 from the header conduit 21. This permits utilizing. if desired. a constant cross-sectional area for the hose 25 without any substantial losses to a series of nozzles 29 in the flexible hose 25. The nozzles 29 are located on the bottom edge of the hose for directing the heated medium directly onto the upper surface of the ice 12. The feeder hoses 27 also reduce torsional freedom of the flexible hose 25. thus assuring that the nozzles 29 are pointing downwardly as the flexible hose 25 is dragged over the ice surface.  
  The flexible hose 25. shown in detail in FIG. 5. consists ofsections 30 connected in end-to-end relation by Y-coupling members 31 to which is also connected the feeder hose 27. The hose sections 30 are preferably weighted on the under surface by members 32 spaced at longitudinal intervals or alternatively. continuous throughout the length. The weights 32 maybe provided as shown in FIG. 6 by lead or other heavy weight material embedded in a portion of the wall of the hose. The nozzles 29 are formed by small apertures extending through a wall of the hose and directed downwardly with the apparatus in position for directing jets of heated fluid medium onto the ice surface. The jets are spaced longitudinally along the hose at appropriate locations for effectiveness in melting the ice and of a size to deliver a sufficient quantity of heated medium also to be effective in melting a narrow slit in the ice. The flexible hose 25 may be insulated throughout its length or portions thereof and this may be provided by an insulated covering. or alternatively. the hose may be con structed of an insulating material. Alternatively. or in addition thereto. the hose may be heated throughout its length or portions thereof by. for example. electric resistance elements embedded in the hose or mounted on the outer surface thereof.  
  An alternative arrangement for the flexible hose 25 is shown in FIGS. 7 and 8 and which consists of rigid hose sections 33 hingedly interconnected in end-to-end relation by pins 33A. Each hose section 33 has a plurality of nozzles 29 directed downwardly. such nozzles being spaced apart longitudinally along the hose section. Each hose section 33 is provided with a coupling member 34 for connecting a feeder hose 27 thereto. The length of hose sections 33 may vary one from the other and sufficient joints are provided to provide flexibility necessary for the hose to be dragged over the ice surface and remain in contact therewith during dragging. It will be obvious in each instance as the vessel proceeds forwardly the trailing end of the hose is located in the slit formed thereby and progressively is disposed below the ice surface.  
  The general object of the present invention is to provide a hose 25 which can follow closely the ice surface being melted so that the nozzles 29 are most always in close proximity or direct contact with the ice melted thereby. Thus. a flexible hose is preferred. However. rigid hose sections may be used and mounted in such a manner as to move and effectively accomplish the same result. FIGS. 2 and 3 illustrate a further embodiment which incorporates two further flexible hoses 25A located laterally to the left and to the right of the cantilevered beam 13 (see FIG. 2). The flexible hoses 25A are carried on arms 40 and 41, pivotally attached by respective mountings 42 and 43 to the cantilevered beam 13 at positions spaced longitudinally therealong. Pivotal movement of the respective arms 40 and -31 may be effected by use of hydraulic piston cylinder assemblies. electric motors. cables or the like. none of which is shown. The arms are shown in FIG. 2 projecting perpendicularly outward from the cantilevered beam 13 positioning the flexible hoses 25A at their maximum distance from the beam and which. preferably. is generally in alignment with the respective lateral outmost sides of the vessel. or therebeyond by distances of approximately I 5 ft. depending upon appropriate location to facilitate the ice breaking operation. The pivotally mounted arms 40 and 41 provide means for variously positioning the flexible hoses 25A at varying distances from the hose 25.  
  In FIG. 3. the respective arms 40 and 41 are illustrated pivoted rearwardly toward the vessel moving the trailing end of the flexible hose 25A to a position more closely adjacent the vessel and also inwardly in a position closer to the beam than in the position illustrated in FIG. 2.  
  In FIG. 4. the cantilevered beam 13 is illustrated pivoted to the left of its normal forwardly projecting position. thereby moving the flexible hoses 25 and 25A along a different path of travel. This facilitates changing the direction of travel of the vessel during forward travel in an ice-breaking operation.  
  From the foregoing. it is seen there is provided apparatus and method for improving ice-breaking capabilities of a vessel by dragging flexible hoses and/0r flexibly linked tubes or hoses or a combination thereof across ice at positions which become critical to fracture as the vessel proceeds forwardly. These hoses are suspended from beams and/or across arms cantilevered in front and laterally to the left and right of the prow of the boat. They are connected by conduit means to a source of steam and/or wet steam and/or hot water with nozzles being located on the downward side for directing hot jets against the ice surface. For reasons of safety and economy. low pressures are preferred. As the nozzles glide directly over the ice surface. the fluid jets melt and/or erode slits into the ice which act as rails for subsequently-following parts of the hoses. Because of the direct contact between the nozzles and the ice. the efficiency of heat transfer and/or erosion effects of the jets is highest while the mechanical flexibility precludes permanent damage of buckling which is typical in rigid devices required in highpressure jets as in the prior art. In the present invention. low pressure steam is preferred as this is a relatively economical form of energy of a fluid medium A further advantage is that low pressure steam is easy to handle and the expertise for handling is normally available within the crew of a vessel. The fluid jets form slits through. as mentioned. melting and/or eroding into the ice. thereby weakening the ice. reducing the required thrust for proceeding through the ice. While a force for bending an elastic beam or a plate increases with the third power of the thickness of the beam or plate (and subsequently the power requirement at constant speed of the boat). the power requirement for melting and/or eroding a slit is linear with the depth. Further. at relatively low speeds which are typical for ice-breaker operations prior to ramming (2 to 5 knots). the amount of waste heat available from the power plant for the vessel is usually sufficient to generate the required amount of steam. Thus. by utilizing waste heat and/or additionally utilizing a cheap form of energy. expensive energy at the shaft for propelling the vessel is saved. as well as reducing the impact loads at the how which. in turn. reduces maintenance costs of replating the hall.  
  The method and apparatus of the present invention is also useful in open sea and/or slush ice. Open sea ice consists of floating ice floes covering the water and slash appears when a denseice cover is melting. The resistance of a vessel in such instances is due to frictional forces in combination with ice formation at the hall. The viscosity of the two-phase fluid. i.e. ice and water through which the vessel proceeds. is increased as compared to the viscosity of water alone. By changing slightly the positions of the front lateral jets to positions laterally of the hull and injecting steam along the hall. the viscosity in the boundary layer is changed. Thus. the viscous drag of the vessel is reduced. This method also may be employed for suppressing ice formation along the water-line of the hull and to free a beset vessel. As previously mentioned. the slight lateral movements provided by swivel mounting for the cantilevered beam and/or other means such as. for example. lines attached to the drag ends of the flexible hoses. manoeuverability of the vessel can be improved while proceeding through ice-infested waters. It is proposed that the flexible hoses be relatively small. for example. 1 e 2 inches in diameter and operating at pressures up to 100 psi. It is proposed also that steam be provided in quantities ranging from 20.000 100.000 lbs. per hour depending. of course. upon the size of the vessel and thickness of ice to be broken. 1n the arrangement illustrated. it will be obvious increased steam pressures in the flexible hoses will have a tendency to straighten the hose. pressing the same with greater force against the ice surface. Thus. effectiveness in cutting cannot only be controlled by the quantity of steam delivered. but also. varying the force of contact of the flexible hose with the ice surface being melted.  
  in the foregoing. the hose which is dragged over the surface is described as being flexible or rigid sections linked together. Obviously. other mechanical means may be utilized to adapt the hose for following the contour of the ice and the term flexibility herein is meant to include any hose which is adapted to be dragged over and follow the contour of the ice surface. the purpose being to maintain contact between the nozzles and the portion of the ice being melted.  
 I claim:  
  1. In a method of breaking ice in the path of travel of a vessel. the improvement comprising dragging a flexible hose having a series of nozzles in contact with the ice and directing jets of a heated medium from the nozzles of the hose against the contacted area of the ice.  
  2. Apparatus for forming a slit in an ice mass in the path of travel of a vessel. comprising:  
 a. a vessel:  
 b. a flexible hose having a plurality of nozzles in se ries along a portion of the length thereof:  
 c. means mounted on said vessel and connected to one end of said hose for dragging the same over the ice surface forwardly of the vessel during forward movement of such vessel. said nozzles being lo cated on a side of the hose in contact with the ice during dragging thereof; and  
 means supplying a heated medium under pressure to said hose during use of said apparatus.  
  3. Apparatus as defined in claim 2. wherein said means mounted on said vessel comprises a beam cantilevered forwardly from the prow of the vessel during use of said apparatus and including further means suspending the hose from said beam.  
  4. Apparatus as defined in claim 3 including means for pivotally mounting said beam on said vessel.  
  5. Apparatus as defined in claim 4 wherein said beam is pivotablc about a vertical axis.  
  6. Apparatus as defined in claim 4 wherein said beam is pivotable about a horizontal axis.  
  7. Apparatus as defined in claim 3 including a header conduit supported by said beam and extending longitudinally therealong for supplying the heated medium to said hose.  
  8. Apparatus as defined in claim 7 including feeder conduits connected to said header conduit and flexible hose at positions respectively longitudinally along the beam and said flexible hose.  
  9. Apparatus as defined in claim 8 including valves for controlling the supply of heated medium to said flexible hose.  
  10. Apparatus as defined in claim 2 including means restraining torsional movement of said hose.  
  11. Apparatus as defined in claim 2 including weights on said flexible hose along the generating line of said nozzles compensating against reacting lifting forces on the flexible hose.  
  12. Apparatus as defined in claim 2 including two further flexible hoses each having a series of nozzles therein and means for suspending the same laterally respectively on opposite sides of the flexible hose defined in claim 3 to drag such further flexible hoses over the ice surface. thereby providing. means for forming three slits in the ice mass in the path of travel of the vessel.  
  13. Apparatus as defined in claim 12 wherein said two further flexible hoses are movably mounted for selectively varying the distance of the same from the flex ible hose disposed therebetween.  
  14. Apparatus as defined in claim 2 wherein said flexible hose comprises a plurality of rigid hose sections hingedly interconnected in end-to-end relation.  
  15. Apparatus as defined in claim 14 including conduit coupling means on each of said rigid hose sections and feeder hoses connected to each of said coupling means.  
  16. Apparatus as defined in claim 2 wherein said heated medium comprises steam.