Ships – Vessel raising and docking
Reexamination Certificate
2003-01-15
2004-12-28
Swinehart, Ed (Department: 3617)
Ships
Vessel raising and docking
C114S045000, C405S003000
Reexamination Certificate
active
06834604
ABSTRACT:
FIELD OF INVENTION
The present invention relates to apparatus for lifting and carrying ships over shallow areas of harbors, rivers and the like.
BACKGROUND
The presence of localized shallow regions along a watercourse has always been a problem for ships entering harbors and moving along rivers. Shallows have been addressed in various ways, including the following: When the water level varies with time, such as due to tides or flow, then a ship can await the favorable condition. A vessel may be initially designed for the draft the shallow will allow. The vessel may be off-loaded or partially loaded initially. Dredging may be used, to artificially remove the shallow region. However, all these alternatives have known disadvantages of time, transport cost, or maintenance cost.
Another technology which has been used, and which is subject of the present invention, dates from around 1688. Then, large Dutch merchant ships returning from the East Indies were inhibited by shallow river bars from entering the Zuyderzee in Holland. A system was devised to partially raise the ships out of the water and move them across the bars. Two camels, in the form of long, narrow, watertight barges, shaped to match the ship's rounded hull, or bilge, were placed on the opposing sides of the ship. They were connected to each other by sling-like cables running beneath the ship hull. The camels were partially filled with water and submerged, the cables were made taut, and then the camel ballasts were pumped out. Thus, the buoyancy of the assembly was increased and the ship was raised out of the water, to reduce its draft, sufficient to pass over the shallows. In ensuing years, development of dredging technology and canal locks supplanted the use of the camels.
In the early 1800's, increased-size whaling ships had difficulty passing over the harbor bar at Nantucket Island, off southern Massachusetts, U.S. In the mid-1840's, a modem version of the Dutch camels was used. Spaced-apart camels were rigidly connected by a wooden floor structure, upon which the ship would sit. The assembly was floated under a ship and the semi-submerged camels were raised, so the ship could be moved across the bar. There was a big improvement in convenience, over having two separate camels. Steam power, for pumping water and powering tugs, also helped a lot. Analogous problems were encountered in the mid-1800's with river and canal traffic, especially abetted by seasonal change in water levels. Abraham Lincoln, later President, obtained U.S. Pat. No. 6469, for an improvement on the Dutch technology, where the camels were inflatable.
Currently, some different kinds of devices are known in commerce for lifting vessels or for transporting them. Dry docks are rigid selectively submersible structures, used for lifting vessels from the water, typically for maintenance and repair of the hull. After a ship is floated onto a semi-submerged stationary dock, the dock is raised, to contact the hull of the vessel along the hull. Cribbing or the like is carefully pre-placed on the floor of the dock, so the ship hull is contacted and supported at numerous points along its length, to avoid any concentration of load on the hull or dock, due to bends in the keel and hull-penetration fittings and other irregularities. Typically, it takes many hours and even days, to configure a dry dock, get the ship in place, and to raise the dock and vessel from the water. Floating dry docks are sometimes made as separate segments, which are bolted or otherwise joined together to form a unitary whole of desired length. When docks are raised while holding a ship, the draining and raising of the segments is carefully controlled. Dry docks may be occasionally moved along sea lanes when they are relocated, but generally they are not adapted for moving about while containing ships. Specialized ships are used for ocean going transport of vessels and other things which either cannot move or be moved across the sea. Those special ships have a deep draft and a conventional hull shape. They are semi-submersible, for receiving a floating ship or other object on a large platform space between the bow and stern. Their design makes them unsuited for use with any shallows.
Certain patents describe art having some relation to the present invention. U.S. Pat. No. 3,736,898 to Yamura U.S. Pat. No. 3,736,898 to Yamura describes a floating dry dock made of two connected pontoon sections, with means for keeping the pontoons floating level by selectively changing the buoyancy of chambers within the pontoon sections. U.S. Pat. No. 4,510,877 to Bloxham describes a dry dock, useful also as a submergible barge, which has a deck which lacks any flotation chamber and has a cradle to support the hull of a vessel. U.S. Pat. No. 5,285,743 to Connelly describes a U-shape cross section dry dock which receives within it a submersible raft like dock portion carrying a ship or the like. U.S. Pat. No. 6,155,190 to Gronstrand describes a dry dock mounted on an aircushion vehicle for over-ground transport, where the ship being carried is supported by a keel guide in combination with a low pressure air bag structure. U.S. Pat. No. 6,152,065 to Gronstrand shows a floating boat lift where different compliant support means are used, including a net supported by springs and a vee shape cradle mounted on springs.
While the kinds of equipment mentioned serves certain purposes, getting camels in place and sized-right for the job, when ships vary greatly in dimension, is a problem. Dry docks are used for raising ships from the water, but the conventional way of using them is tedious and slow. Dredging is time consuming and entails impacts on the environment and shipping lanes, which have to be accommodated. Thus, there is a need for improvements, with respect to carrying ships over shallows when in laden condition.
SUMMARY
An object of the invention is to provide a quick and economic way of moving laden and unladen ships over shallows. A further object is to provide a means for lifting and transporting a ship while accommodating irregularities and avoiding any overstressing or changing of the lengthwise contour of the ship hull.
In accord with the invention, a ship is positioned over, and then lifted by, a platform which is buoyantly supported by ballast tanks. The platform, and thus the ship, is raised rapidly by draining the ballast tanks, sufficient to make the draft of the structure associated with the platform less than the draft which the ship previously had, and sufficient to clear the shallows to be crossed. The assembly is moved across the shallows, by either self-propulsion of the platform apparatus, or by other means, such as towing. Then the ship is released by filling the ballast tanks. Typically, the hull will be partially immersed when the assembly moves across the shallow, and the ship is kept engaged with the platform by a combination of frictional engagement with the platform and lines.
In accord with the invention, a submergible floating vessel has a bottom which comprises a platform for contacting and lifting the bottom of a ship hull. Preferably, the vessel is comprised of a multiplicity of rigid U-shape sections, at least some of which sections are connected together by means, such as hinge assemblies, which enable pivoting of one section relative to an adjacent section. Gaps, between wing walls of abutting sections of a U-shape cross section vessel, accommodate relative rotational motion of the sections. During lifting, the platform surfaces of the sections change orientation, to accommodate any up or down bend along the length of the ship hull. Preferably, the length of a U-shape section is less than the useful width between the vertical wing walls, so one section may be carried by another section.
Preferably, the platform is surfaced with a material or structure which is compliant, or adaptive, to local irregularities in the bottom of the hull, such as fittings. Thus, local overstressing is avoided due to contact of a hull protuberance with the platform surface, wh
O'Neil David A
Wood William A.
Nessler C.
Seaworthy Systems, Inc.
Swinehart Ed
LandOfFree
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