If you throw the Grapple line to catch the ring and then jump towards the wall, Lara will most likely fall into the water. So, jump and whilst in midair, throw the Grapple line to catch the ring.

Make Lara hang beneath the thick line on the wall. The longer the cable is, the higher momentum Lara will gain. Position the camera behind Lara, because it will be easier that way.

When Lara reaches the highest momentum to the left (she should be above the thick line), release the Left button and quickly press Down and Jump.

If you do it correctly, Lara will grab the end of the ledge.