Editing PT boat (section)

====Board of Inspection and Survey====
The [[Board of Inspection and Survey]], headed by Rear Admiral [[John W. Wilcox Jr.]], conducted comparative service tests<ref name=board>Board of Inspection and Survey, ''Report of Comparative Services Tests of Motor Torpedo Boats Held July 21–24, 1941 and August 11–12, 1941 at New London, Connecticut'' (Navy Department, August 14, 1941)</ref> off [[New London, Connecticut]], from 21 to 24 July 1941, using the following boats:

* ''PT-6'': {{convert|81|ft|m|adj=on|abbr=on}} Higgins; 3 Packard {{convert|1200|hp|abbr=on}} engines.
* ''PT-8'': {{convert|81|ft|m|adj=on|abbr=on}} Philadelphia Navy Yard; aluminum hull; 2 [[Allison Engine Company|Allison]] {{convert|2000|hp|abbr=on}} engines, 1 [[Hall-Scott]] {{convert|550|hp|abbr=on}} engine.
* ''PT-20'': {{convert|77|ft|m|adj=on|abbr=on}} Elco; 3 Packard {{convert|1200|hp|abbr=on}} engines; equipped with special propellers; special strengthening added to hull framing and deck.
* ''PT-26'', ''-30'', ''-31'', ''-33'': Same as ''PT-20'', except with standard propellers and without special strengthening.
* ''PT-69'': {{convert|72|ft|m|adj=on|abbr=on}} Huckins; 4 Packard {{convert|1200|hp|abbr=on}} engines.
* ''PT-70'': {{convert|76|ft|m|adj=on|abbr=on}} Higgins; 3 Packard {{convert|1200|hp|abbr=on}} engines.
* One {{convert|70|ft|m|adj=on|abbr=on}} MRB-8 (Motor Rescue Boat), built for the [[Royal Navy]] by Higgins; 3 Hall-Scott {{convert|900|hp|abbr=on}} engines.

Each member of the board conducted an independent inspection of every boat class, evaluating them for structural sufficiency, habitability, access, arrangement for attack control, and communication facilities.<ref name=board /> Boats were also evaluated under two conditions of armament loading: loaded and fully equipped with four {{convert|21|in|cm|abbr=on}} torpedoes and sufficient fuel to operate 500 NM at 20 knots; and fully loaded with two {{convert|21|in|cm|abbr=on}} torpedoes and ten {{convert|300|lb|abbr=on}} depth charges with sufficient fuel to operate {{convert|500|nmi|km smi|abbr=on}} at {{convert|20|kn|km/h mph|abbr=on}}.<ref name="board" /> Boats would have their tactical parameters of each design determined by photographs from an airship.<ref name="board" />

=====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 />

=====Second open-ocean trial=====
Because of the problem with ingot loading, a {{convert|185|nmi|km smi|abbr=on}} trial with the PTs fully fitted out was conducted on 12 August 1941. Four boats—''PT-8'', ''PT-69'', ''PT-70'', and MRB—returned and Elco sent two new boats, ''PT-21'' and ''PT-29''. During this trial, boats faced heavier seas, as high as {{convert|16|ft|abbr=on}}. All except the Huckins (''PT-69'') completed the run. The Huckins withdrew because of a bilge stringer failure. The Higgins 76-footer (''PT-70'') completed the entire run but also suffered structural failures: attachments between planking and web frames pulled loose and deck fastenings near engine hatches showed extensive failures. ''PT-21'' suffered minor cracks in the deck in the same location, but not to the same extent, as previously observed in ''PT-26'', ''PT-30'', and ''PT-33''. ''PT-29'' was assigned as a pace boat with ''PT-8'' in order to generate a pounding comparison.<ref name=board />

The average speed results from the {{convert|185|nmi|km smi|abbr=on}} course were: Elco 77-footer (''PT-21''), {{convert|27.5|kn|km/h mph|abbr=on}}; Higgins 76-footer (''PT-70''), {{convert|27.2|kn|km/h mph|abbr=on}}; Higgins MRB and Philadelphia Navy Yard boat (''PT-8''), {{convert|24.8|kn|km/h mph|abbr=on}}. Accelerometers were again installed in the pilot house of each boat, but the readings were incomplete because the violent motion of the boats made observations difficult and in some cases necessitated abandonment of the observing stations. Further, many of those taken were beyond the normal range of the instruments and were considered inaccurate. Elco boats were found to pound heavily and confirmed previous reports of crew discomfort.<ref name=board />