A mooring buoy is a firmly anchored buoy for boats to tie off to rather than drop anchor. A complete system often includes a fixed attachment to the sea bed and a weighted rope connected to a floating buoy. Reef-mooring buoys are used by boaters in areas where anchors can damage fragile coral and other sea life. Traditional and helix-anchored buoys are also used to secure ships for long periods of time in heavy-duty environments.
In many parts of the world, including the US, Caribbean and Asia, coral reefs co-exist with recreational and commercial boaters. A traditional boat anchor and chain can easily damage or rip apart a coral reef. Since the 1970s, mooring buoys have been used near reef tracts to provide alternative coral-safe anchoring systems. Three different types of reef-mooring buoy systems are frequently used in the Florida Keys, Hawaii and islands around the world. In each of these systems, smaller boats can tie off to each other while larger ships attach directly to the buoy pick-up lines.
The Halas reef-mooring buoy system includes an eye bolt cemented into the sea floor. Developed in the 1980s in Florida, it uses a weighted three-part polypropylene rope to attach the bolt to the buoy. Two or three eye bolts in a triangle configuration can also be used to support boats up to 100 feet (33 meters) long. The Halas system requires a solid, preferably flat sea bottom to drill and cement into. Based on a utility pole anchor, another common boat-mooring buoy called the Manta-Ray system works well in gravel, sand and clay.
The Manta-Ray is similar to the Halas system except that it uses a utility anchor and rod instead of a cemented eye bolt. The anchor mechanism is driven deep into the sea bottom, then upward force is applied to lock the anchor into place. The installation time and effort for a Manta-Ray mooring buoy is much less than for a Halas system. Traditional reef mooring systems can also be used in areas with a soft or otherwise unstable sea bottom. This type generally includes a large concrete block, engine block or other heavy device attached by a chain to the buoy line.
For waters which don't contain coral or other fragile life, a standard heavy-duty mooring buoy can be used. In this kind of system, the mooring buoy anchor is generally a large mushroom type. Each buoy is attached to a light chain, which is linked to a heavy chain shackled to the anchor. During winter, a long and narrow buoy with cement ballast can avoid freezing into the ice better than a standard round buoy.
A Helix-anchored mooring buoy can be used to secure larger boats even in very stormy conditions. This type of system is based on a helix screw anchor designed for lighthouses in the 1800s. It has been successfully used during hurricanes and generally provides many times the holding power of a traditional heavy-duty anchor. Also known as a sea screw, a Helix anchor is screwed as far as possible into the sea bottom with a hydraulic torque motor. It can be used with most types of soil, including clay and mud.