The hull shape of the Elco and Higgins PT boats were similar to the warped "planing hull" found in pleasure boats of the time (and still in use today): a sharp V at the bow softening to a flat bottom at the stern. A common characteristic of this type of warped hull is the "rooster tail" in the wake. Unlike the actual "planing hull" Huckins, which planed at 10-11 knots, the Elco and Higgins PT boats were intended to plane at higher speeds (PT 71 and PT-103 classes at around 27 knots, and the PT-265 and 625 classes at around 23 knots). The Elco, Higgins and Huckins companies used varying lightweight techniques of hull construction which included two layers of double diagonal mahogany planking utilizing a glue-impregnated cloth layer between inner and outer planks. These planks were held together by thousands of copper rivets and bronze screws. The overall result was an extremely light and strong hull which could be easily repaired at the front lines when battle damage was sustained. According to Robert McFarlane, the US Navy built the hulls of some PT boats partially from 3,000-year-old white cedar logs recovered from sphagnum bog in New Jersey.