Friday, June 20, 2014

Why has my mooring moved?

"Why has my mooring moved?" is one of the most common questions we receive from new mooring owners. In 99% of all cases the short answer is "it hasn't."

On some situations a mooring will move. If it is undersized, improperly set, or there is a very bad storm it might get dragged across the ocean floor. But in most cases it is the mooring ball, and not the mooring itself, that has shifted. 

The position of a  mooring ball can vary greatly depending on wind, tide, current, and whether or not there is a boat on the mooring. The image below shows 4 different possible positions of a mooring ball in relation to the actual anchor. 

In all 4 examples the chain is the same length (minus slight artistic variations). 

A. represents a mooring that has all the chain piled up close to the mushroom, with no wind current or boat affecting the mooring. This is the only situation that will result in the ball accurately marking the location of the anchor. This is incredibly rare.

B. represents a mooring that has been stretched out but does not currently have any wind, tide, or boat forces being applied. This is the ideal "at rest" example. The chain has been stretched out but only the minimum amount of chain is being lifted out of the mud.

C. represents a mooring that is completely stretched out and being pulled on hard by wind, current, a boat, or a combination of all three. This is an undesirable situation because the chain is lifted out of the mud which leaves it susceptible to corrosion and reduces the mooring's holding power.

D. represents is the same example as C. only it is at low tide.

The moral of this story is that a mooring ball does not usually accurately mark the location of the anchor. It will move in a large circle depending on wind, current, tides, and boat weight. The greater the forces applied, the greater the movement will be. 

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