Ideally, the mooring line is 2 to 3 times the depth of the water at highest high water. This ratio of water depth to mooring line is called scope. A high scope allows for the least hydraulic force to be applied to the anchor block as the buoy is far away from the anchor. However, sometimes this is not practical as the length of the mooring line allows the buoy to move too far away from its anchor position. This movement is referred to as the watch circle. If the watch circle causes the buoy to move too far out of position or for it to hit shore or another floating object, it will need to be reduced. The lower the scope, the more wear on your mooring line and the larger your anchor block should be. Your mooring line must be able to be supported by the buoy selected.

The size of the anchor block is determined by the buoyancy of the buoy, the type and length of mooring line being used, and the environmental conditions. The anchor block ideally has a submerged weight that is 3 times the buoyancy of the buoy minus the mooring weight. However, this can result in some very large anchor blocks. This is where environmental conditions come into play. If the location allows for a large scope of the mooring line, a smaller anchor block can be used. Also, if the buoy location is sheltered without large swells, the anchor can be made smaller as well.

The size of the buoy is determined by two main factors: water depth and who the primary user is. The deeper the water, the heavier the chain mooring is, and a large buoy is needed to support the weight. Hybrid mooring lines made from rope and chain can help mitigate this. When the primary user is a container ship, a large buoy is needed so the buoy can be seen from far away, providing the ship with adequate time to make adjustments. The large buoy also provides a higher focal plane for marine lanterns for nighttime visibility.

When installing a buoy, you should make sure you are following the local regulations. There are often conditions around where you can place a buoy, as well as its size, shape, and colour, depending on the application. You may also be required to provide special decals and reflective tape to the buoy. Our team is available to help you select the right buoy to ensure compliance. You can contact your local Coast Guard or Transportation Agency before purchasing a buoy.