Douglas OarlocksDouglas oarlocks orient the blade at 6% from vertical on the power stroke to lock the blade on the water for maximum rowing efficiency. On the return stoke the oarlocks pitch the forward edge up to keep from catching a crab when feathering. To use them on Shaw and Tenney oars, you will need to purchase Martinolli D Sleeves. They are also used on our oars for sliding seat rowing shells with outriggers. 100% manganese bronze. The pins are 2" long and 1