Capstans. Why Capstans?. Rather than using the hand-over-hand method of retrieving lines, the capstan offers a mechanical advantage that is both faster and safer. The capstan does the heavy lifting with only a small amount of effort. The maximum speed of the line retrieval depends on the rotational speed of the drum. The benefit is that the retrieval speed can be adjusted by decreasing the tension on the retrieved line, maintaining control over a very heavy load with little effort.. This useful