The present disclosure pertains generally to buoys and, more particularly, to vertical marker buoys.
Challenges may be presented in finding equipment at the surface of a large body of water, particularly where the equipment has been released after being held underwater in a deep sea or ocean. Finding the equipment may be especially difficult when it is impractical or undesirable to use a permanent line from the equipment to a surface float. In a prior art solution, a mechanism may be attached to the equipment to do one of two things. The mechanism may release a float on a line to the surface. Alternatively, the mechanism may drop ballast and allow the equipment with attached floats to ascend to the water's surface.
Equipment released from a deep mooring takes a considerable amount of time to reach the surface. For example, the deeply moored equipment may take a few minutes to an hour to reach the surface, depending on the depth, drag and buoyancy of the equipment. Over the course of the time it takes for this equipment to reach the surface, both the equipment and the float that is carrying it to the surface, may be acted on by currents. Depending on the speed of the current, the equipment can be carried far out of sight of a recovery vessel. Even without currents, objects passing through the water column may have some horizontal movement or glide. This movement or glide can cause the equipment to be carried out of sight.
Not only are challenges encountered in finding equipment at the water's surface, but additional challenges are encountered in finding equipment on the water's surface after the equipment's release from an undersea mooring. Not only might the equipment disappear due to the distance it travels, but the equipment can also be hidden by waves. When the equipment is in the trough of a wave, objects with minimal vertical height above the water surface may be very difficult to detect. This difficulty may increase with distance between the floating equipment and recovery vessel.
When operating in fairly shallow depths, in order to mark equipment, it may be adequate to have a float double as both a source of buoyancy and a marker of the location of the equipment. This solution may work reasonably well so long as it takes only a short while for the float to reach the surface and provided that the bottom location of the float is precisely known. However, in progressively deeper water, the uncertainty in the location of the equipment on the bottom becomes much greater. Objects descending through the water column tend to glide in one direction or another, and they are also pushed by currents, sometimes in different directions and at different depths.
Even if means are available to determine the location of the float (or equipment) on the bottom, the same forces of glide and current will again act when the float is released and ascends to the surface. There is a need for a solution to more reliably determine the location of equipment released from significant subsea depths.
One way of increasing the detectability of equipment on the surface is to use a very large float, which primarily provides flotation, but also performs double duty as a marker. However, using a single device for purposes of both flotation and detection involves design compromises. The typical float is a sphere. Spheres may make poor radar targets even if the spheres have metal surfaces. Also, the weight of the equipment keeps much of the float submerged, reducing its detectability. Large floats, moreover, are difficult to safely deploy and recover. They may not fit through a typical chute used for such purposes, and they can be too heavy to move without a crane.
There is a need for a lightweight solution; one sufficiently slender to fit through a chute and to project high enough above the surface of the water to be easily detected.
There is further a need for a solution for determining the location of equipment that is easier to deploy and recover than existing solutions.
The present disclosure addresses the needs noted above by providing a vertical marker buoy and a method of deploying the buoy for detection of surface equipment.
In accordance with one embodiment of the present disclosure, a vertical marker buoy is provided for detecting the location of surface equipment. The buoy comprises a first tubular member having an inner cylindrical wall, an outer cylindrical wall, a proximal end, a distal end and a length. The buoy further comprises at least one flotation device having an inner cylindrical wall that is fixedly attached to the proximal end of the outer cylindrical wall of the first tubular member, wherein the width of the at least one flotation device is less than the length of the at least one flotation device. The buoy also comprises at least one detection indicator configured to indicate a location for the buoy. The detection indicator is mounted at the proximal end of the marker buoy.
The buoy also includes a bail that is rotatably attached to the first tubular member. The bail is sufficiently long and wide to rotate around the length of the first tubular member. The vertical marker buoy is configured to maintain positive buoyancy when the surface equipment is attached to the vertical marker buoy. The vertical marker buoy is configured to be positioned in a substantially vertical position on the surface of a body of water when the vertical marker buoy is in use. The vertical marker buoy is capable of being deployed from an underwater depth.
These, as well as other objects, features and benefits will now become clear from a review of the following detailed description, the illustrative embodiments, and the accompanying drawings.
The accompanying drawings, which are incorporated in and form a part of the specification, illustrate example embodiments and, together with the description, serve to explain the principles of the invention. In the drawings:
A vertical marker buoy and associated deployment method are described herein for detection of surface equipment. The buoy and method provide a faster and more reliable means to locate equipment, e. g., at the sea surface or suspended by a float. The subject equipment may have been released from an underwater mooring, or it may have otherwise been held underwater. The present buoy and method may be used in situations where a line from the moored equipment to a surface float is impractical or undesirable.
The marker buoy may have a proximal end that projects above the waterline which increases both the likelihood and the speed of detection. The marker buoy characteristics may be designed to significantly increase its detectability at the surface, and to ensure that it can withstand the significant subsea depths to which it may be taken. The vertical marker buoy of the present disclosure can be taken down several thousand meters below sea level. It does so with a minimum of mass and bulk, facilitating deployment and recovery, and also increasing the ease and safety of handling on deck.
When the vertical marker buoy appears at the surface of a body of water, the marker buoy floats vertically at the water's surface. When the buoy is on the surface of a body of water, the buoy's proximal end may appear above the waterline. The proximal end may include a detection indicator that indicates the location of the buoy and the attached equipment. The distal end of the marker buoy may have a bail and mooring line that permit the attachment of surface equipment to other floats. These additional floats may provide the flotation needed to support the equipment until the equipment is recovered. The vertical marker buoy may appear at the surface of a body of water after it has been deployed to and/or from a subsea depth or mooring. The buoy described in the present disclosure can be deployed from underwater/subsea depths or moorings that are thousands of meters below the surface of a body of water.
Referring now to
Tube 110 is lightweight, particularly since the weight at the proximal end of tube 110 and/or buoy 100 must be counterbalanced by weight at the distal end. Tube 110 may be composed of PVC material or other lightweight material that can be buoyant. If buoy 100 is too heavy, it may be difficult for buoy and associated equipment to float to the surface so that the equipment may be detected or located.
Another tube 120 or pipe having a greater diameter than tube 110 is disposed around the first tube 110 or pipe. Tube 120 is sometimes described herein as first tubular member. The outer wall of tube 110 may be sized so that it is sufficiently small to fit within the inner cylindrical wall of tube 120. Tube 110 may be connected to tube 120 via attachment means such as screws, nuts and bolts. Alternatively, a reducing fitting may also be used to attach tubes 110, 120 to each other. For example, if the inner cylindrical wall of tube 120 is four (4) inches and the outer cylindrical wall of tube 110 is one and one half (1½) inches, the reducing fitting could be substantially four (4) inches at one end and one and one half (1½) inches at the other end. Tubes 110, 120 may be plastic pipes, composed of e.g., polyvinyl chloride (PVC).
Flotation devices 130, 135 have inner cylindrical walls that may be fixedly attached to the outer cylindrical wall of tube 120 via attachment means such as screws, nuts and bolts. Flotation devices 130, 135 may be disposed around the outer circumference of tube 120. The flotation devices 130, 135 are comprised of a material that is sufficiently light to provide positive buoyancy to other parts of the buoy 100. The material is lighter than water. The material may also be selected for flotation devices 130, 135 based on how long the surface equipment to be attached is desired to be kept underwater and the depth to which the equipment will travel. The material should also be resistant to deformation at such depths. If the surface equipment is going to be underwater for a short period, e.g. a few minutes, and in relatively shallow water, then the selection is easier than if the surface equipment will be submerged for a lengthy period of time in deep water. The volume of the material used for flotation devices 130, 135 may also be a factor. Syntactic foam is an example of a material that may be used for flotation devices 130, 135. Syntactic foam is a composite material that incorporates hollow particles in a matrix. The material may be chosen according to calculations known in the art. Syntactic foam maintains buoyancy over time. Syntactic foam is heavy relative to its buoyancy, but it can be cast into virtually any shape, and it can be machined without fear of damaging its structural integrity or its water-tightness. These qualities may allow for selection of precisely the desired amount of flotation. Syntactic foam may also withstand severe impact without damage.
Another material that may be used to construct flotation devices 130, 135 is glass. Hollow glass hemispheres may be used as flotation devices 130, 135 and may be held together by a vacuum. These hollow glass hemispheres may have more buoyancy for their volume and weight than syntactic foam. Such glass spheres are commercially available, e. g., TELEDYNE BENTHOS® glass spheres. However, because the glass hemispheres do not typically have a center hole, it may not be possible to simply slide a tube 120 through them. It may be desirable to hold these glass hemispheres together into a vertical column by some configuration or connection device (such as placement inside a tube or surrounding with a cage or bolting together plastic “hard hats” designed to fit the floats). Then a pole, or possibly two lengths of pole, one on the top and one on the bottom, may be attached to whatever is holding them together. Another material, hollow plastic floats, may be unreliable because at depth they may deform and lose buoyancy. Flotation devices 130, 135 may be fixedly attached to tube 120 via stainless steel bands. In the buoy 100 of the present illustration, flotation devices 130, 135 may be about three times as high as they are wide. For example, the height of flotation devices may be thirty-three inches (33″), while the width may be about eleven inches (11″) to thirteen inches (13″).
Mooring line attachment 140 and bail 150 are also illustrated. Bail 150 is composed of material shaped into a tube or rod. Bail may be composed of a lightweight, rigid material, e.g., thin wall type 316 stainless steel tubing, that is sufficiently strong that it can withstand the stresses of deployment and recovery without significant deformation. In the present illustration, bail 150 connects to tube 120 at a place between flotation device 130 and flotation device 135. The bail 150 is attached to the buoy 100 at or slightly below the water line (the level to which the buoy 100 naturally sinks when fully equipped). This is done so that as the buoy 100 is always able to maintain a vertical position.
Bail 150 is sufficiently long to swivel around the length of buoy 100 so that it clears all the buoy components. Bail 150 is able to rotate in order to compensate for varying directions in which attached surface equipment may be pulled. Bail 150 is wider than the flotation devices 130, 135 so that it does not interfere with the operation of other portions of buoy 100.
A mooring line (not shown in
Bail 150 may be accompanied by an auxiliary float (not shown), e.g., a seventeen inch (17″) glass sphere. The float may be attached via a short line (e.g., one to two feet long) to the swivel at the end of the bail 150. The float may help to support the weight of the bail 150 on the surface, to aid the ascent of the marker buoy 100. The float may also be used to help keep the mooring line (which is attached to other floats and the equipment that is being recovered) from getting tangled around the marker buoy 100. If the mooring line becomes tangled around marker buoy 100, the buoy 100 may be incapable of floating vertically and the recovery aids may not be useful. In lieu of being attached to bail 150, mooring line may be attached directly to the tube 120 and its inner cylindrical wall at the distal end of tube 120. After deployment, the buoy 100 may be pulled in by a water vessel or other suitable vehicle or vessel to which the buoy 100 may be attached.
The present buoy 100 differs from the prior art in that some prior art buoys include a mount on the bottom in lieu of bail 150. This bottom mount may work fine on deployment, when a buoy is descending towards the bottom, and may work reasonably well when a buoy is initially released and heads back up to the surface. It does not work well on the surface, where due to winds, waves or currents the buoy will be pushed or pulled towards a horizontal position, minimizing visibility and likely making whatever aids to detection with which it might be equipped only marginally functional.
One possible alternative to a bottom mount is to attach the mooring line about where the bail 150 attaches. This would solve the problem on the surface, but then there would be a potential problem when the buoy 100 descends towards the bottom and again when it ascends to the surface. In both instances, it would likely be traveling through the water at about a right angle to the direction of travel. This would cause more drag, increasing the time it takes to get to the surface and probably also causing more horizontal travel, both of which would likely take the buoy farther from the vessel. More importantly, the increased drag could potentially damage the structure or any attached instruments.
The ballast 160 is comprised of external weights. The ballast 160 is attached to the bottom of the pipe and to a smaller section of pipe, which is designed to serve as a mast and hold an aid to recovery. Ballast 160 may be comprised of materials e.g., those used for scuba diving equipment. Ballast 160 may be held in place onto tube 120 with stainless steel bands. The weight of ballast 160 should be sufficient to counterbalance the weight of the remaining elements of buoy 100 so that buoy 100 remains vertical when the attached equipment reaches the surface of a body of water.
When the buoy 100 is fully equipped, the vertical marker buoy 100 maintains positive buoyancy and is less dense that the water around it so that it can remain in a substantially vertical position when at the surface of a body of water. The weights that are included in ballast 160, as well as the weights in the equipment to be attached, should be taken into account when making such a buoy 100 to maintain positive buoy. The heavier the buoy structure and attached equipment, the more difficult it may become to maintain positive buoyancy. Therefore, it may be desirable to use lightweight materials when making buoy 100. The positive buoyancy also enables any detection indicators or recovery aids such as flag 115, radio beacon (not shown), flasher (not shown) or radar reflector (not shown), to be seen at or near the surface of the water.
With the present buoy 100, the functions of flotation and detection are separated into different structures, allowing each to be individually optimized. The standard approach of having a buoy or set of buoys that do both is invariably a compromise. The compromise solution reduces how much of the buoy is above the surface of the water and, hence, how likely or easy it is for a vessel to spot the buoy on the surface. Separation of function also allows the portion of the buoy providing each function to be smaller and lighter. This allows for much easier handling both on the deck of a ship and in deployment and retrieval.
The present buoy's vertical design increases the detectability of equipment once it is on the surface by increasing the distance above the water level that the buoy is visible and, hence, increasing the distance at which a vessel can spot the buoy. The standard solution of mounting on a sphere or horizontal float provides a much shorter range of detection or a much smaller probability of detection. Use of the vertical buoy shape also provides an advantage for deployment and recovery, as the slim profile allows it to be deployed and recovered through a chute. In accordance with the present disclosure and as shown in the drawings, the height of the buoy is significantly greater than its width. The flotation devices 130, 135 are generally much shorter in length than the combined length of tubes 110 and 120. This is not possible with a large diameter float. Moreover, this design is lightweight, whereas existing solutions tend to be much heavier. Additionally, this design stays more stationary in the water. Horizontal buoys roll considerably more with the waves, and other buoys may suffer from this shortcoming. For example, buoys may roll more with the waves when they have flotation devices that are wider in relation to the water's surface than they are high so that they can project above the water's surface.
The shape of flotation devices 130, 135 will cause the present buoy 100 to behave much more like a true spar buoy. An object that is floating vertically, like a spar buoy, may be much less affected by passing waves. It may remain nearly perfectly vertical in most conditions.
The vertical marker buoy may be easily seen by someone in a boat. The greater the distance from which it can be seen, the better. The higher the buoy 100 stays above the surface, the farther away it can be seen due to waves and, at longer distance, the curvature of the earth. The height of vertical marker buoy 100 may be further increased by lights (not shown in
The present vertical marker buoy 100 is long and thin. As such, it can be easily slid over the railing of a ship, regardless of whether it is going into the water or being pulled out. The buoy 100 is also sufficiently narrow to fit comfortably into many chutes that are designed for ropes or other types of lines or equipment.
Buoys in general may be towed behind a ship just prior to deployment in order to reduce chances of the mooring line (not shown) getting wrapped around some part of the entire mooring system. During this time, and also during the time the typical buoy is descending into water and again when the buoy is rising to the surface, there is a chance that part of the mooring line will wrap or twist around some part of the one or another of the object being deployed. This chance is minimized with a streamlined shape such as the vertical marker buoy 100,
A number of design considerations come into play in designing the vertical marker buoy 100. Considerations include: how high above the water the recovery aids (e.g., flashers, radio direction finders, radar reflectors, flags or other daytime visual markers, etc., not shown in
Once initial specifications are provisionally decided, then material selection can begin, perhaps starting with the tube 120.
Tubes 110, 120 form the backbone to which the flotation devices 130, 135, ballast 160 and instruments, such as radar reflectors (not shown in
Fiberglass tubes are a widely available and relatively inexpensive option for tubes 110, 120, as are certain other types of plastic tubes such as polycarbonate or Lexan. Thin-walled tubing of a metal such as an appropriate marine grade of aluminum alloy could also be used. It may be desirable that the chosen material not become brittle at the near-freezing water temperatures encountered at deep depths. It may also be desirable that the chosen material not soften and distort when stored on the hot deck of a vessel.
The underwater section of tube 110 and/or tube 120 could be made of a heavier (per unit length) material than that which is above water, with the weight of the tube 110 and/or 120 forming part of the needed counterweight (such as ballast 160).
Another option for the underwater section of the tube 120 is to use a material that is neutrally or positively buoyant, such as Ultra High Molecular Weight Polyethylene. This would potentially allow a larger counterweight to be used and it could be used to maximal effect by placing all the weight at the far end of the tube 120. Overall weight calculations may be used to maintain an upright position for the vertical marker buoy 100 when the buoy is in operation. The vertical marker buoy 100 with its payload of instruments (not shown in
Flotation device 135, the lower and mostly underwater portion of the flotation, must be sufficient to support the weight of any attached recovery aids, including the weight of mounting brackets, etc., for the recovery aids. Flotation device 135 must also be sufficient to support the weight of the in-air portion of tube 110 and/or tube 120, weight of the in-air portion of the flotation device 130, the in-water weight of the in-water portion of the tube, and the in-water weight of the counterweight (such as ballast 160).
The ballast 160 may be slightly heavier than the combined weight of any attached recovery aids, including the weight of mounting brackets, etc. for the recovery aids, the weight of the in-air portion of tube 110 and/or tube 120, and the weight of the in-air portion of the flotation device 130. This slight excess of weight of the ballast 160 when combined with the weight of the in-air portion of the flotation 130, will be approximately adequate to hold the buoy 100 vertical if the height of the tube 110 above the waterline is about equal to the depth of the tube 110 and/or 120 below the waterline.
The weights of some components of the buoy 100 can be taken as something that is fixed. Those of the others can be varied somewhat. The tube 110 and/or 120 can be lowered to reduce the net weight of buoy 100 and also to increase the ability of the buoy 100 to float vertically (by locating the ballast 160 farther below the waterline). The ballast 160 can be made slightly heavier or lighter, affecting both the stability of the buoy 100 and the height of the recovery aids above the waterline.
If weights have been accurately calculated, only a few small iterations of the height of tube 110 and/or 120 or amount of ballast 160 should be sufficient to result in buoy 100 staying vertical and quickly returning to vertical if it is pushed over to one side.
Generally, the higher the recovery aids are held above the waterline, the better, limited by the ability of the buoy 100 to strongly maintain its upright posture.
The marker buoy of the present disclosure optionally provides a mounting surface for aids to detection and recovery such as a radio beacon, flashing light, or radar reflector. Referring now to
In addition, this buoy 200 also includes a radio beacon 260 and a flasher 270, which are attached to the mast. The radio beacon 260 may be used to transmit at a specified radio frequency in order to permit the buoy 200 and attached surface equipment to be found. The specified frequency may be designated in order to reduce the possibility that another entity is transmitting at the specified frequency. Radio beacon 260 may transmit a continuous or alternatively, periodic, radio signal with information that may include its location. The radio beacon 260 may transmit on a specified radio frequency. Beacon 260 may be purchased along with a compatible receiver (not shown). The radio beacon 260 may be chosen based on the distance it needs to transmit as well as its ability to withstand the desired subsea depth. Tube 220 protects the radio antenna (not shown in
Flasher 270 may simply be a flashing light that illuminates to show the physical location of the surface equipment. It may be particularly useful in the dark. The radio beacon 260 and flasher 270 may aid recovery of the buoy 200. It may be desirable to mount these instruments a distance above the surface of the water to increase the likelihood that they will be detected by a searching vessel. Mounting these instruments on a spherical or horizontal float, which is more traditional, provides only a very limited range of detection.
Referring now to
Referring now to
A tubular member 420 has an inner cylindrical wall through which radar reflector 405 may be mounted using attachment means such as screws, nuts or bolts.
Flotation devices 430, 435 have inner cylindrical walls that attach to the outer cylindrical wall of tube 420. Flotation devices 430, 435 may be disposed around the outer circumference of tube 420. The flotation devices 430, 435 are comprised of a material that is sufficiently light to provide positive buoyancy to other parts of the buoy 400. Bail 450 is rotatably mounted to tube 420 using a swivel connector or other suitable attachment means. The swivel connector should be configured in such a manner as to attach to the vertical tube 420 and the attached horizontal portion of bail 450.
The radar reflector 405 serves as a mounting surface for flasher 470 which may be used to indicate the location of buoy 400 and associated equipment. Flasher 470 extends above radar reflector. In lieu of flasher 470, other signal devices may be used, such as radio beacons. Having the radar reflector 405 also act as a mount may provide a lighter and more efficient solution than the prior art, which includes attaching a radar reflector or other instruments to a mast. Weight saving may be an important factor in vertical buoy design, as any weight added near the top may need to be compensated by adding more ballast at the bottom. There may be very little excess buoyancy, so the additional weight of a radar reflector 405 and flasher 470 could exceed the capacity of a given design to stay vertical. The flasher 470 may be used in lieu of a mast, and may be attached directly to the radar reflector 405. The buoy 400 (including components such as a radar reflector 405), may be sunk to depths at or around four thousand (4000) meters, and then released. With the proper selection of materials and surface equipment, the buoy 400 could be designed to go to greater or lesser subsea depths as needed. Stainless steel band 498 is disposed at the distal end of the bail where it extends into a U-shape. Stainless steel band 498 is similar to a standard hose clamp with a screw.
In the embodiment of
At the distal end of spherical flotation device 730, the distal end of tube 720 and the distal end of buoy 700, mooring line attachment 740 is placed next to stainless steel washer 733 in order to aid in securing washer 733 to tube 720. Mooring line 740 can be clipped to shoulder screw 742 at bottom of fiberglass tube 720 via fusible link for deployment. In this embodiment, mooring line attachment 740 is a metric U-bolt, with regular hex nut plus jam nut.
Ballast 760 is shown at the distal end of buoy 700. In this illustration, the ballast 760 is composed of five (5) small steel barbell weights, two and a half pounds (2.5 lbs) each with a polyvinyl chloride (PVC) sleeve as a spacer. As this illustration shows, no bail is needed. Ballast 760 is secured to tube 720 at the proximal end of tube 720 by shoulder screw 742 and stainless steel washer 761. At the distal end of the tube 720 and/or buoy 700, ballast 760 is secured by stainless steel washer 762 and shoulder screw 763. Shoulder screw 763 has a nylon insert nut. Equipment 765 is attached to the buoy 700 via an attachment line 767. In this illustration, equipment 765 is at the surface of the body of water.
The foregoing description of various preferred embodiments have been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the buoy and method to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The example embodiments, as described above, were chosen and described in order to best explain the principles of the buoy and method of deployment and their practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the buoy and method be defined by the claims appended hereto.
The United States Government has ownership rights in this invention. Licensing inquiries may be directed to Office of Research and Technical Applications, Space and Naval Warfare Systems Center, Pacific, Code 72120, San Diego, Calif., 92152; telephone (619)553-5118; email: ssc_pac_t2@navy.mil. Reference Navy Case No. 102,684.
Number | Name | Date | Kind |
---|---|---|---|
747114 | Allison | Dec 1903 | A |
2099506 | Winckler | Nov 1937 | A |
2110596 | Gaede | Mar 1938 | A |
2119854 | Day | Jun 1938 | A |
2903716 | Zasada | Sep 1959 | A |
3037217 | Mandra | Jun 1962 | A |
3397413 | Houtsma | Aug 1968 | A |
3423777 | Feyling | Jan 1969 | A |
3550549 | Horton | Dec 1970 | A |
3818428 | Phipps | Jun 1974 | A |
3858166 | Hammond | Dec 1974 | A |
3893201 | Mallory | Jul 1975 | A |
4042990 | Donaldson, Jr. | Aug 1977 | A |
4067202 | Reed | Jan 1978 | A |
4136415 | Blockburger | Jan 1979 | A |
4949643 | Bowersett et al. | Aug 1990 | A |
5095841 | Santos et al. | Mar 1992 | A |
6062158 | Blanchard | May 2000 | A |
6102758 | Smith | Aug 2000 | A |
6261142 | Fiotakis | Jul 2001 | B1 |
7819712 | Winter | Oct 2010 | B1 |
8047590 | Hamme | Nov 2011 | B1 |
Entry |
---|
“Sur-Mark™ Marker Buoys,” Taylor Made, Online Catalogue, http://www.taylormadeproducts.com/cgi-bin/catalog.pl?item—id=71, 2016, pp. 1-3. |
“Regulatory Buoys,” Taylor Made, Online Catalogue, http://www.taylormadeproducts.com/cgi-bin/catalog.pl?item—id=73, 2016, pp. 1-3. |
“Mast Buoys,” Taylor Made, Online Catalogue, http://www.taylormadeproducts.com/cgi-bin/catalog.pl?item—id=74, 2016, pp. 1-3. |
“Multi-Purpose and Channel Marker Buoys:Sentinel® Buoy,” Tideland, Online Brochure, http://www.tidelandsignal.com/2014/data/Buoys-small-1400/MULTIPURPOSE-BUOYS-REV09.pdf, 2016. |
“Mooring Recovery Float,” McClane Labs, Online Brochure, http://www.mclanelabs.com/sites/default/files/sub—page—files/McLane-Mooring-Recovery-Datasheet—0.pdf, 2016, 1p. |
“VHF Radio Locating System,” MetOcean, Online Brochure, http://www.metocean.com/sites/default/files/files/products/pdfs/rf-700a1.pdf, 2016, pp. 1-2. |
“Visual locating system,” MetOcean, Online Brochure, http://www.metocean.com/sites/default/files/files/products/pdfs/st-400a—0.pdf, 2016, pp. 1-2. |