Flotation device
A flotation device is disclosed having first and second spaced-apart, elongated, substantially rigid structural members and a plurality of buoyancy tubes held in compression between the first and second structural members. The compression connection between the ends of the buoyancy tubes and the sides of the structural members in this configuration can improve the structural integrity of the flotation device. The structural members can be made of glue-laminated timber, which has high strength and stability. The buoyancy tubes can be made of high-density polyethylene. A deck structure can be supported on top of the first and second structural members. Thus, thermal welding of the deck structure to the buoyancy tubes typically can be avoided. A flotation assembly also is disclosed including two flotation devices connected by a flexible hinge assembly.
This claims the benefit of the earlier filing date of prior U.S. Provisional Application No. 60/701,137, filed Jul. 20, 2005, which is incorporated herein by reference.
FIELDThis disclosure relates generally to flotation devices, such as flotation devices having multiple buoyancy tubes.
BACKGROUNDFloating docks with timber superstructures supported by hollow or foam-filled pipe displacement members have become commonplace due to their simplicity and ease of construction. Typically, these docks are constructed using rigid pipes, such as steel, corrugated aluminum or plastic pipes, arranged longitudinally along the dock axis in unit lengths of 20 to 60 feet. Since metal pipe materials are susceptible to the corrosive effects of salt water, the use of plastic pipe has become increasingly common. High-density polyethylene (HDPE), for example, is virtually unaffected by salt water or by solvents and chemicals often found in the marine environment. Also, HDPE pipe is readily available in a wide variety of diameters and wall thicknesses.
In the construction of floating docks, the formation of a flat deck over cylindrical pipes can be challenging. Some conventional floating docks include clamping devices affixed to the pipes to support the deck. Clamping devices, however, are prone to slip and can, in some cases, crush the pipes. Other conventional floating docks include saddle structures over the pipes. For example, certain floating docks manufactured by Ferguson Enterprises, Inc. (Washougal, Wash.) include thermally-welded saddles made from flat plates of the same basic material as the pipes (i.e., HDPE). The welds, however, may become fatigued and fail due to the repeated application of flexural forces. Moreover, unlike with steel and aluminum, there are few standards governing the welding of plastic materials. At a minimum, such welds must be carefully executed to minimize the risk of failure.
U.S. Pat. No. 6,796,262 (the '262 patent) discloses the arrangement of short sections of plastic pipe transversely across the width of a floating dock, rather than longitudinally. To join these short pipe sections, a longer, vertically disposed plate that is at least as wide as the pipe diameter is welded to both ends of the sections, joining them in ladder-rung fashion at both ends. These vertically oriented plastic plates, however, are susceptible to the above-mentioned bending stresses imposed by mooring forces and associated vertical and lateral loading cycles. For example, if a boat moored on one side of the dock is caused to move in the opposite direction of a boat (or pile anchorage) on the opposing side of the dock, it is possible, over time, to pull the vertically oriented plate away from the welded pipe ends, causing separation failure.
Due to production limitations in manufacturing HDPE plates, the assemblies disclosed in the '262 patent are typically limited to less than 20 feet in length. To form larger structures, the assemblies must be joined together, such as by butt-welding the plates of adjacent assemblies or by incorporating articulating connectors positioned at frequent intervals. Butt-welds can be weakened to the point of failure by repeated vertical or horizontal bending. The use of articulating connectors also can be disadvantageous. For example, the short (e.g., 10 to 20 foot) lengths of the assemblies often match ambient wave lengths. Thus, it is possible to cause a harmonic reaction, resulting in excessive pitching and rolling of the overall structure. This motion can be physically and mentally unsettling to boaters attempting to walk on the dock. In addition, typical articulating connectors require extensive anchorages and, therefore, contribute excessively to the cost of manufacturing the dock.
SUMMARYDisclosed herein are embodiments of a flotation device and embodiments of a method for making the flotation device. The flotation device can include first and second spaced-apart, elongated, substantially rigid structural members and a plurality of buoyancy tubes positioned between the first and second structural members. Some embodiments also include a wale held in compression against an outer surface of the first or second structural member. The first and second structural members and or the wale can comprise GLULAM. In various embodiments, the first and second structural members are sized to either partially or completely cover the ends of the buoyancy tubes. The structural members also can be sized to extend substantially the entire length of the flotation device.
The buoyancy tubes can be oriented substantially perpendicular to and held in compression between the first and second structural members. In some embodiments, the buoyancy tubes comprise HDPE. The buoyancy tubes also can house foam cores to assist in flotation. To help resist shear forces, at least one of the buoyancy tubes can have a cross-sectional area from about 200 to about 100,000 square inches. Between the structural members, the buoyancy tubes can be arranged in parallel, transversely extending rows. In some embodiments, each row has at least first and second buoyancy tubes positioned end-to-end and separated by an intermediate structural member extending substantially perpendicular to the rows of buoyancy tubes. Some embodiments of the disclosed flotation device do not include any shear-resisting elements placed in compression between the first and second structural members that are not buoyancy tubes, tensioning members or intermediate structural members.
A deck structure can be supported on top of the first and second structural members. A utility tube can be positioned between at least a portion of the buoyancy tubes and the deck structure. In some embodiments, there are substantially no supports for the deck structure located between the first and second structural members that are not intermediate structural members.
The buoyancy tubes can be held in compression, for example, by a plurality of tensioning members secured to the first and second structural members. The tensioning members can comprise metal rods. In some embodiments, the tensioning members extend through the first and second structural members and are held in place against outer surfaces of the first and second structural members. For example, the tensioning members can have threaded end portions that are held in place against outer surfaces of the first and second structural members using nuts. Washers also can be included to distribute the force against a larger portion of the outer surfaces of the first and second structural members. In some embodiments, the tensioning members are positioned such that they would support the buoyancy tubes if the buoyancy tubes were not held in compression between the first and second structural members. For example, the tensioning members can be positioned around the circumference of each buoyancy tube.
The disclosed flotation devices can be made, for example, by positioning a plurality of buoyancy tubes between and substantially perpendicular to a pair of structural members and securing a plurality of tensioning members to the first and second structural members. The tensioning members then can be tightened to place the buoyancy tubes in compression between the structural members.
Also disclosed are embodiments of a flotation assembly. Some embodiments of the disclosed flotation assembly include first and second flotation devices each comprising a plurality of buoyancy tubes held in compression between structural members oriented substantially perpendicular to the buoyancy tubes. The first and second flotation devices can be connected by a flexible hinge assembly comprising an elastomeric material. In some embodiments, the flexible hinge assembly also includes plates secured to substantially vertically oriented major planar surfaces of the structural members of the first and second flotation devices. The flexible hinge assembly can include brackets secured to the plates. In these embodiments, the elastomeric material can be used to connect a bracket of the first flotation device to a bracket of the second flotation device. The elastomeric material can, for example, be a belting material having substantially horizontally oriented major planar surfaces. A gap-filling deck plank can be mounted above the belting material, such as using at least one bolt and a spacer disposed between the belting material and the gap-filling deck plank.
BRIEF DESCRIPTION OF THE DRAWINGS
Disclosed herein are embodiments of a flotation device, embodiments of a method for making the flotation device and embodiments of a flotation assembly. Some embodiments of the flotation device include structural members, which can, for example, be beams of glue-laminated (GLULAM) timber or concrete panels. GLULAM beams are available in a variety of lengths, such as 40 to 70 foot lengths. The disclosed embodiments also can include transversely-arranged buoyancy tube sections between the structural members. The buoyancy tube sections typically need not be bonded or secured to one another. Instead, the buoyancy tube sections, which may or may not have end caps welded to seal each end, can be captured by compression and bolt shear within the walls of opposing structural members. GLULAM beams, in particular, are of enormous structural value, and are capable of resisting cyclic loads, mooring loads and both vertical and horizontal bending forces common to marinas.
Certain conventional panelized wale floats that do not include buoyancy tubes use one or more tiers of flat-laid diaphragm plates placed in compression within a panel frame to maintain the strength and integrity of opposing wales under horizontal loading. However, under extreme conditions, vertical loading can cause racking in the vertical direction. In contrast to these conventional floats, some embodiments of the disclosed flotation device take advantage of the cross-sectional area of buoyancy tube sections to provide shear force resistance vertically as well as horizontally. Therefore, these embodiments better resist racking regardless of the direction of environmental forces, and can obviate the need for additional bulkheads or other shear-resistant elements to maintain the desired strength and integrity.
As used herein, the term “tube” refers to any elongated member with a hollow portion and is not limited to a cylindrical tube. Accordingly, the cross-sectional profile of the buoyancy tubes in disclosed embodiments can be any shape, such as a circle, square, rectangle, triangle, or various combinations thereof. In some embodiments, the cross-sectional area of the buoyancy tubes is from about 100 to about 100,000 square inches, such as from about 200 to about 100,000 square inches or from about 300 to about 100,000 square inches.
First and second transversely spaced-apart structural members 104 and 106 extend the length of the flotation device 100 adjacent opposite ends of the buoyancy tubes 102. The structural members 104, 106 desirably are wooden or GLULAM timber beams, although other suitable materials also can be used. For example, the structural members 104, 106 can be vertically oriented concrete panels. In the embodiment shown in
At least one tensioning member, such as the illustrated tensioning rods 108, is used to place the buoyancy tubes 102 in compression between the structural members 104, 106. As shown, the tensioning rods 108 extend transversely across the flotation device 100 and through corresponding openings in the structural members 104, 106. The tensioning rods 108 can be made from any material with relatively high tensile strength, such as metal. In some embodiments, the tensioning rods 108 are made from a corrosion-resistant metal, such as stainless steel. The use of rigid tensioning rods 108 improves the strength of the overall flotation device 100. Flexible tensioning members, however, also can be used. For example, in some embodiments, the tensioning rods 108 are substituted with taut wires or cables.
The structure created by compressively loading the structural members 104, 106 and the buoyancy tubes 102 is well suited to resist bending or racking of the flotation device 100 under vertical and horizontal loads. The cylindrical shape of the buoyancy tubes 102 in this embodiment makes them especially effective for resisting vertical and horizontal forces. Using the buoyancy tubes 102 as structural elements can obviate the need to provide bulkheads or other shear-resisting elements placed in compression inside the flotation device 100. Moreover, by using compression, the structural integrity of the flotation device 100 does not depend upon thermal welds between the buoyancy tubes 102 and other components. Thermal welds, such as thermal welds between HDPE shear panels and HDPE buoyancy tubes are particularly susceptible to failure.
As best shown in
As shown in
In the flotation device 200, each transverse row includes two buoyancy tubes 204. Other embodiments, however, can include more than two buoyancy tubes per row with transversely spaced-apart intermediate structural members extending between the adjacent ends of buoyancy tubes in each row. For example,
The disclosed flotation devices can include various arrangements of rows of buoyancy tubes. For example, some embodiments include evenly spaced rows of buoyancy tubes along their entire length. Other embodiments include grouped rows of buoyancy tubes with the spacing between the groups being greater than the spacing between individual tubes in each group. For example,
In the flotation device 600 shown in
The flotation device 600 shown in
Multiple flotation devices can be interconnected to each other to form a dock assembly, preferably using flexible hinges. For example,
The hinge assembly 704 interconnects the flotation devices 702a, 702b while allowing for relative listing and twisting of the flotation devices. An enlarged view of the hinge assembly 704 is shown in
The outer T-shaped brackets 716a, 716b are secured to inner, elongated T-shaped brackets 722a, 722b, respectively, by inner bracket bolts 724a, 724b. The inner T-shaped brackets 722a, 722b are interconnected by one or more layers 726 (two layers shown in the illustrated embodiment) of flexible material extending along the length of the inner T-shaped brackets. The layers 726 overlap a horizontal flange portion of the inner T-shaped brackets 722a, 722b and are secured thereto by bolts 728 extending vertically through layers and the horizontal flange portion of the inner T-shaped brackets. The layers 726 can be made of any suitable natural or synthetic elastomeric material, such as rubber. In particular embodiments, the layers 726 are made of a strong, flexible belting material, such as PLYLON® fabric-carcassed, rubber belting material manufactured by the Goodyear Tire and Rubber Company of Akron, Ohio. As further shown in
The U-shaped brackets 818a, 818b also are secured to inner, elongated L-shaped brackets 824a, 824b, respectively, by inner bracket bolts 826a, 826b. The inner L-shaped brackets 824a, 824b are interconnected by one or more layers 828 (two layers shown in the illustrated embodiment) of flexible material extending along the length of the inner L-shaped brackets. The layers 828 overlap a horizontal flange portion of the inner L-shaped brackets 824a, 824b and are secured thereto by bolts 830 extending vertically through layers and the horizontal flange portion of the inner L-shaped brackets. The layers 828 can be made of any suitable natural or synthetic elastomeric material, such as rubber. In particular embodiments, the layers 828 are made of a strong, flexible belting material, such as PLYLON®. As further shown in
The following examples are provided to illustrate certain particular embodiments of the disclosure. Additional embodiments not limited to the particular features described are consistent with the following examples.
Example 1 This example describes a specific embodiment of a flotation device similar to the flotation device 100 illustrated in
This example describes a specific embodiment of a flotation device similar to the flotation device 400 illustrated in
In view of the many possible embodiments to which the principles of the disclosed invention may be applied, it should be recognized that the illustrated embodiments are only preferred examples of the invention and should not be taken as limiting the scope of the invention. Rather, the scope of the invention is defined by the following claims. I therefore claim as my invention all that comes within the scope and spirit of these claims.
Claims
1. A flotation device comprising:
- first and second spaced-apart, elongated, substantially rigid structural members;
- a plurality of buoyancy tubes positioned between the first and second structural members and oriented substantially perpendicular to the first and second structural members; and
- a plurality of tensioning members secured to the first and second structural members such that the buoyancy tubes are held in compression between the first and second structural members.
2. The flotation device of claim 1, wherein the first and second structural members extend substantially the entire length of the flotation device.
3. The flotation device of claim 1, wherein the first and second structural members are sized to completely cover the ends of the buoyancy tubes.
4. The flotation device of claim 1, wherein the first and second structural members comprise glue-laminated timber.
5. The flotation device of claim 1, wherein the buoyancy tubes comprise high-density polyethylene.
6. The flotation device of claim 1, wherein the tensioning members comprise metal rods.
7. The flotation device of claim 1, wherein the tensioning members are positioned such that they would support the buoyancy tubes if the buoyancy tubes were not held in compression between the first and second structural members.
8. The flotation device of claim 1, wherein the buoyancy tubes house respective foam cores.
9. The flotation device of claim 1, wherein the first and second structural members are sized to partially cover the ends of the buoyancy tubes.
10. The flotation device of claim 1, wherein the buoyancy tubes are arranged in parallel, transversely extending rows, each row having at least first and second buoyancy tubes positioned end-to-end and separated by an intermediate structural member extending substantially perpendicular to the rows of buoyancy tubes.
11. The flotation device of claim 1, wherein the flotation device does not include any shear-resisting elements placed in compression between the first and second structural members that are not buoyancy tubes, tensioning members or intermediate structural members.
12. The flotation device of claim 1, wherein the tensioning members extend through the first and second structural members and have nuts tightened on their outer end portions to place the buoyancy tubes in compression between the first and second structural members.
13. The flotation device of claim 1, further comprising a wale held in compression against an outer surface of the first or second structural member.
14. The flotation device of claim 1, wherein the cross-sectional area of at least one of the buoyancy tubes is from about 200 to about 100,000 square inches.
15. The flotation device of claim 1, further comprising a deck structure supported above the first and second structural members.
16. The flotation device of claim 15, having substantially no supports for the deck structure located between the first and second structural members that are not intermediate structural members.
17. The flotation device of claim 15, further comprising a utility tube positioned between at least a portion of the buoyancy tubes and the deck structure.
18. A flotation device comprising:
- first and second spaced apart, elongated, substantially rigid structural members comprising glue-laminated timber; and
- a plurality of buoyancy tubes positioned between the first and second structural members and extending in a direction that intersects the first and second structural members.
19. The flotation device of claim 18, wherein the buoyancy tubes comprise high-density polyethylene.
20. The flotation device of claim 18, wherein the buoyancy tubes are arranged in parallel, transversely extending rows, each row having at least first and second buoyancy tubes positioned end-to-end and separated by an intermediate structural member extending substantially perpendicular to the rows of buoyancy tubes.
21. The flotation device of claim 18, wherein the cross-sectional area of at least one of the buoyancy tubes is from about 200 to about 100,000 square inches.
22. The flotation device of claim 18, further comprising a deck structure supported above the first and second structural members.
23. The flotation device of claim 22, having substantially no supports for the deck structure located between the first and second structural members that are not intermediate structural members.
24. The flotation device of claim 18 in combination with another flotation device, the flotation devices interconnected by a flexible hinge assembly.
25. The combination of claim 24, wherein the flexible hinge assembly comprises at least a piece of a flexible belting material connected to each flotation device.
26. A flotation device comprising:
- a plurality of buoyancy tubes; and
- means for holding the buoyancy tubes in compression.
27. A flotation assembly comprising:
- a first flotation device comprising a plurality of buoyancy tubes held in compression between structural members oriented substantially perpendicular to the buoyancy tubes;
- a second flotation device comprising a plurality of buoyancy tubes held in compression between structural members oriented substantially perpendicular to the buoyancy tubes; and
- a flexible hinge assembly attaching the first flotation device to the second flotation device, wherein the flexible hinge assembly comprises an elastomeric material.
28. The flotation assembly of claim 27, wherein the flexible hinge assembly further comprises plates secured to substantially vertically oriented major planar surfaces of the structural members of the first and second flotation devices.
29. The flotation assembly of claim 28, wherein the flexible hinge assembly further comprises brackets secured to the plates, and the elastomeric material connects a bracket of the first flotation device to a bracket of the second flotation device.
30. The flotation assembly of claim 27, wherein the flexible hinge assembly comprises a belting material having substantially horizontally oriented major planar surfaces and a gap-filling deck plank mounted above the belting material.
31. The flotation assembly of claim 30, wherein the gap-filling deck plank is secured to the belting material with at least one bolt and the flexible hinge assembly further comprises a spacer positioned between the gap-filling deck plank and the belting material.
32. A method for making a flotation device comprising,
- positioning a plurality of buoyancy tubes between and substantially perpendicular to a pair of structural members;
- securing a plurality of tensioning members to the first and second structural members; and
- tightening the tensioning members to place the buoyancy tubes in compression between the structural members.
Type: Application
Filed: May 18, 2006
Publication Date: Jan 25, 2007
Inventor: David Rytand (Anacortes, WA)
Application Number: 11/437,116
International Classification: B63B 35/44 (20060101);