Another advance in dinghy sailing was introduced in the 1930s, when the technique of trapezing was introduced. This involves using the crew to provide more leverage (than possible by hiking out) to keep the sails vertical and the boat balanced; doing this can prevent the boat from capsizing, by hanging outside the boat on a harness and rope attached to the 'hounds' or upper mast. As a result, the boat is easier to keep upright, and the sails can deliver maximum power most of the time. While trapezing can be helpful and increase speed, it can also be very dangerous if the crew is not wearing a quick-release harness or is inexperienced. The quick-release harness allows the crew to unstrap themselves quickly so as to not get forced under the boat if it were to capsize.