Patent Application
20070178782
The present invention relates to marine buoys as aids to navigation.
Thousands of buoys are employed as aids to navigation, serving, among other things, to indicate channel locations, warn of hazards to navigation, and announce speed or wake restrictions. Navigation buoys are constantly exposed to harsh environmental forces and occasional collisions from watercraft. Sturdy buoy construction and design is required. Additionally, to facilitate the visibility and/or operability of many buoys it is desired that the buoys have a relatively high height above the waterline while demonstrating minimal pitching and rolling during heavy seas, thus requiring the inertia of a heavy overall weight combined with substantial buoyancy and ballasting that achieves a low center of gravity.
To satisfy these requirements, navigation buoys are usually constructed of heavy gauge steel for durability and ballasted with solid ballast at a location below the waterline. Concrete is a commonly used ballast material. Buoys designed to fulfill these requirements are thus very heavy and difficult to handle.
Because of the substantial weight of navigation buoys, buoy retrieval and deployment typically requires relatively large ships with high capacity davits and other specialized equipment (buoy tenders). Even with such equipment, handling heavy buoys can be difficult and dangerous, particularly when high winds and seas complicate retrieval and deployment operations. The capacity of buoy tenders to store buoys once onboard may also be restricted by the heavy weight of the buoys. The stability and trim of buoy tenders may be adversely impacted if too many buoys are stored on deck.
Accordingly, it can be seen that there is a need for a lightweight navigation buoy to facilitate in the buoy's transportation, launching, and retrieval when not deployed that can be altered to exhibit the stability characteristics of the much heavier-constructed conventional buoys when deployed.
In view of the foregoing, it is an object of the present invention to provide a navigation buoy with a liquid-ballasting/-venting system in which a predetermined amount of liquid ballast can be added or removed, resulting in a buoy that can be made substantially lighter and easier to handle when not deployed, but can be efficiently altered to possess the necessary weight and stability of currently designed navigation buoys when deployed.
It is a further object of the present invention to provide a buoy with a liquid-ballasting/-venting system that further increases the stability by providing one or more internal baffles to minimize any free-surface movement of said liquid ballast.
It is a further object of the present invention to provide a buoy with a square bottom plate wide enough to provide a roll-resistant surface when the buoy is stored on deck.
These and other advantages of the present invention will be better understood in light of the detailed description of a preferred embodiment.
Turning to
A body 12 of the buoy 10 is preferably constructed from a lightweight or light gauge material, relative to conventional heavy gauge carbon steel buoys. Materials such as aluminum, light-gauge stainless or carbon steel, or non-metallic materials can be selected. The use of lighter-weight materials can result in a weight reduction of up to 65% for a given size of buoy. Material selection is at least partially driven by cost and operational constraints. Operational constraints, including suitable protective coatings, may include factors like environmental conditions at a deployed location, traffic density and likelihood of collision, and size/visibility requirements.
The ballasting compartment 30 is sized to accommodate sufficient liquid ballast for the desired stability characteristic, given the size and design of the buoy 10 while deployed. In high-corrosion environments (e.g., saltwater), corrosion-resistant coatings can be applied. If the buoy 10 will be subjected to freezing conditions, an anti-freeze agent can be added to the liquid water ballast.
The liquid ballast can be added-to or removed from the ballasting compartment by a liquid- ballasting/-venting pipe 36. Liquid ballast is externally supplied to or removed through connection 34 at the upper end of the liquid- ballasting/-venting pipe 36 extending through the upper wall 32. The liquid- ballasting/-venting pipe 36 extends substantially to the bottom of the ballasting compartment 30 inside of an inner cylindrical wall 40. Liquid ballast supplied to or removed from connection 34 enters or leaves the ballasting compartment 30 from the lower end of the liquid- ballasting/-venting pipe 36. One-inch diameter communication hole(s) 42 formed in the cylindrical wall 40 convey liquid ballast to or from compartment 30 to pass through the cylindrical wall 40. Baffle plate 44 reduces any free surface movement of the liquid ballast during pitching and rolling of the buoy 10.
Ballast plate 44 is immersed a few inches below the surface of the liquid ballast. Baffle plate 44 is welded to cylindrical wall 40, but is loosely fitted and not sealed to the internal wall of body 12.
A square plate 52 is bolted, or otherwise fastened, to the lower wall 46 of body 12. The weight and hydrodynamics of the plate 52 help maintain the proper orientation of the buoy 10 when deployed. The square plate 52 has a width equal to the widest diameter of buoy 10, which allows the buoy 10 to be stably placed on its side on a flat surface, such as the deck of a ship.
A distal end 54 is adapted to receive a high-strength, flexible tether (not shown). Preferably a high-strength, flexible, elastic tether can be employed. A high-strength, flexible, elastic tether allows the buoy 10 to be securely moored in a given water depth using a shorter scope than would be required for a traditional heavy mooring chain. More accurate positioning of the buoy is thereby made possible.
From the foregoing, it can be seen that the present invention provides a buoy that is lightweight yet still enjoys the stability of a conventional, much heavier buoy when deployed.
In a retrieval operation, a retrieval vessel comes alongside the buoy 10, usually attaching a line to the buoy to ensure the appropriate relative positioning of vessel and buoy during retrieval operations. The retrieval vessel accesses connection 34 and attaches a de-ballasting means, typically a pump or the like, to connection 34. The liquid ballast is then removed from the ballasting compartment 30. The significantly lightened buoy is then lifted from the water, using a crane or davit. The buoy 10 is stored on its side such that the square plate 52 inhibits rolling.
Once the required maintenance has been performed, or whenever deployment is required, the buoy 10 is re-attached to the tether (if detached) lowered into the water, by a crane or davit. A ballasting means, preferably the same as the de-ballasting means (e.g. a pump or the like), is attached to replace the liquid ballast.
Those skilled in the art will appreciate that the present invention is not limited to the embodiments described, but that various modifications and alterations can be made without departing from the scope of the present invention.
