Editing PT boat (section)

=====First open-ocean trial=====
Lastly, there was a demonstration of seakeeping qualities and hull strength by making a run at maximum sustained speed in the open ocean. An accelerometer was installed in the [[pilot house]] of each boat to record "pounding". Conducted on 24 July 1941, this open-water trial, {{convert|190|nmi|km smi|abbr=on}} at full throttle, was referred to by PT personnel as the "Plywood Derby". The course started from the mouth of New London Harbor, to Sarah Ledge, then led around the eastern end of [[Block Island]], then around Fire Island Lightship, finishing at [[Montauk, New York|Montauk Point]] Whistling Buoy.<ref name=board />

At the time, only the Elco 77-footers were loaded with armament. The other competitors had copper ingots added topside (mostly in the turrets) to make up the difference. This resulted in severe conditions for several of the boats during the trial and accounted for the transverse failure in ''PT-70''{{'}}s deck and subsequent hull failure as the copper fell into the hull.<ref name=board /> Nine boats participated in the trial.<ref group="note">''PT-26'' had previously developed deck failures while conducting standardization trials off Block Island on 21 July 1941.</ref> Six boats completed the trial, while three withdrew: ''PT-33'' suffered structural damage off Block Island; ''PT-70'' was damaged by loose copper ingots; and ''MRB'' developed engine trouble at the start of the run.<ref name="board" />

By class, ''PT-20'', an Elco 77-footer, came in first with an average speed of {{convert|39.72|kn|km/h mph|abbr=on}}; followed by ''PT-31'', with an average speed of {{convert|37.01|kn|km/h mph|abbr=on}}; ''PT-69'', the Huckins {{convert|72|ft|m|adj=on}} boat, was third with an average speed of {{convert|33.83|kn|km/h mph|abbr=on}};<ref group=note>The Huckins boat experienced a high pressure oil failure and had to go "Dead in the Water" in order to effect the repair.</ref> ''PT-6'', the Higgins 81-footer, with an average speed of {{convert|31.4|kn|km/h mph|abbr=on}} was fifth; and ''PT-8'', the Philadelphia Navy Yard boat, was last, at {{convert|30.75|kn|km/h mph|abbr=on}}. The other two Elco boats, ''PT-30'' and ''PT 23'' (standby boat), followed ''PT-31'', placing before ''PT-69''.

[[File:PT-31 crossing the "Plywood Derby" finish line at Montauk Point, Long Island, 24 July 1941.jpg|thumb|Second place PT-31 crossing the finish line during the "Plywood Derby".]]

The accelerometers ranked the boats as follows: first was the Philadelphia Navy Yard ''PT-8'' with the least pounding, second was the Huckins ''PT-69'', third was the Higgins ''PT-6'', and last were the Elco 77-footers.<ref name=board />