What does the Dock "A" Cable do?

[Slickcraft]

Originally Posted by jmen24

It puts a tension member in the frame. If you pull up your dock without this line attached and site the A frame you will notice about 4-5inches of sag in the A frame. Then install the tension line and see that that sag reversed into a slight bow after tensioning it. Its sole purpose is to remove the sag, which could in fact cause the frame to buckle.

It's obvious from the photo that jmen24 is correct.