Apparatus for clearing a path through ice

Claim 2

An icebreaking vessel for use in ice-covered waters comprising: a hull adapted to float in water at a characteristic load waterline with a draft determined by the weight of the vessel and its contents, the hull having a bow portion extending above and below the waterline, a platform extending in front of the bow, a flexible skirt extending around at least a portion of the perimeter of the platform and projecting downwardly from the platform, the platform and skirt being joined in substantially air-tight relation to form with the top surface of the ice-covered water a substantially enclosed plenum, the bottom of the skirt being disposed below the waterline of the hull, means coupling the platform and the hull so that propulsion of the hull is effective to move the platform in advance of the hull, and means for forcing air into the plenum under pressure sufficient to depress the level of the water below the plenum to below the waterline of the hull, the draft of the vessel being substantially constant whether or not air is supplied under said pressure to the plenum.

Claim 3

The apparatus of claim 1 wherein the air forcing means is operable to force air into the plenum under sufficient Pressure to depress the water below the plenum to a level below the vessel waterline sufficient to cause a surrounding ice sheet to break from its own weight.

Claim 4

Apparatus of claim 1 wherein the coupling means is arranged for movably connecting the platform to the bow portion of the hull of the vessel to permit vertical movement of the platform relative to the hull in front of the bow.

Claim 5

Apparatus of claim 1 wherein the platform extends rearwardly over the bow, the platform extending laterally a distance greater than the beam of the vessel, and means coupling the platform to the deck of the vessel in substantially air-tight relationship, the bow extending into the plenum.

Claim 6

Apparatus of claim 1 further including means for rapidly shifting the center of buoyancy of the vessel in a fore and aft direction to induce pitching movement of the bow.

Claim 7

Apparatus of claim 4 wherein the coupling means includes hinge means joining the platform along its rear edge to the ship, and means for raising and lowering the front of the platform about said hinge means to lift the platform clear of obstructions.

Claim 8

Apparatus of claim 2 wherein the flexible skirt extends completely around the perimeter of the platform, and said means for forcing air into the plenum includes fans mounted on the platform for forcing air into the space below the platform.

Claim 9

Apparatus of claim 7 wherein said means movably connecting the platform to the hull includes frame members connected to and extending rearwardly from the platform, and roller means rotatably connected to the frame members and positioned to engage the sides of the hull on either side of the bow, the rollers having their axes of rotation substantially parallel to the water, the axes converging at the same angle as the converging sides of the hull at the bow so that the bow wedges between the rollers, and cable means extending between the platform and the hull for pulling the platform frame members and rollers toward the bow of the hull.

Claim 10

An icebreaker comprising a vessel having a pair of fixedly spaced apart hulls adapted to float jointly in water at a characteristic waterline with a draft determined by the weight of the vessel and its contents, a platform supported by the hulls so as to move with the hulls in response to propelling the hulls. The platform being substantially horizontal and projecting in front of the bows of the hulls and extending laterally beyond the beam of the vessel, a flexible skirt extending downwardly from the platform and joined to the platform in substantially air-tight relation. The skirt extending around the perimeter of the platform and terminating at the outside surface of the hulls, a rear flexible skirt extending between the two hulls, air-tight means extending between the hulls from the platform to the rear skirt, the skirts having bottom edges disposed below the vessel waterline whereby a plenum is formed in front of and between the two hulls, and means for pressurizing the plenum with air to a pressure sufficient to depress the water below the plenum to a level sufficient to cause the surrounding ice sheet to break off from its own weight, the draft of the vessel being substantially constant whether or not air is supplied under said pressure to the plenum.

Claim 11

An icebreaker comprising a vessel having a pair of fixedly spaced apart hulls adapted to float jointly in water at a characteristic waterline with a draft determined by the weight of the vessel and its contents, a platform supported by the hulls so as to move with the hulls in response to propelling the hulls. The platform being substantially horizontal and projecting in front of the bows of the hulls and extending laterally beyond the beam of the vessel, a flexible skirt extending downwardly from the platform and joined to the platform in substantially air-tight relation. The skirt extending around the perimeter of the platform and terminating at the outside surface of the hulls, a rear flexible skirt extending between the two hulls, air-tight means extending between the hulls from the platform to the rear skirt, the skirts having bottom edges disposed below the vessel waterline whereby a plenum is formed in front of and between the two hulls, and means for pressurizing the plenum with air to a pressure sufficient to depress the water below the plenum to a level sufficient to cause the surrounding ice sheet to break off from its own weight, the draft of the vessel being substantially constant whether or not air is supplied under said pressure to the plenum.

Claim 12

The apparatus of claim 9 wherein the rear skirt is positioned near the stern of the vessel.

Claim 13

The apparatus of claim 9 further including hinge means securing the platform to the two hulls, and means for swinging the front of the platform upwardly from a horizontal position about said hinge means.

Claim 14

Apparatus of claim 9 further including means for discharging air along the outboard sides of the hulls.

Claim 15

The apparatus of claim 9 further including means for directing air from the pressurized plenum to the outboard sides of the hulls, the air being discharged just below the vessel waterline.

Claim 16

Ice breaking apparatus for use with a vessel having a buoyant hull, a deck and a prOw extending therefrom comprising: a surface effect structure mounted on and attached to the prow and extending in front of the vessel and including a platform with a large areal extent having a flexible material attached to and extending downwardly from the platform to a point adjacent a surface being traversed by the vessel, such flexible material extending downwardly substantially around the underside of the platform to enclose the underside periphery of the platform, said surface effect structure having means mounted in the platform for forcing air below the platform.

Claim 17

Ice breaking apparatus for use with a vessel having a buoyant hull, a deck and a prOw extending therefrom comprising: a surface effect structure mounted on and attached to the prow and extending in front of the vessel and including a platform with a large areal extent having a flexible material attached to and extending downwardly from the platform to a point adjacent a surface being traversed by the vessel, such flexible material extending downwardly substantially around the underside of the platform to enclose the underside periphery of the platform, said surface effect structure having means mounted in the platform for forcing air below the platform.