And BTW, there was more than enough water on the reef edge when the Colorado planes were overhead to completely cover the Bevington Object with or without surf. We calculate the water level at that spot when Lambrecht and company flew over as a little over 2 feet. The Bevington Photo was taken at low tide and the object was sticking up about 20 inches.
The
log of the Colorado shows that the Lambrecht flight was launched at 7:00 am Colorado time.
The Colorado's clock was set 11:30 slow on Greenwich Mean Time, GMT or "Z." So we add 11:30 to 7:00 and calculate the Greenwich Mean Time of the launch as 1830 Z.
From the point of launch to Mckean island is 44 NM and the true course is 065° T, the planes cruised at 90 knots true airspeed, (see attached chart.) The Colorado log shows that the wind at that time was from the east at 12 knots which resulted in a head wind for the planes so that their ground speed was reduced to 79 knots so it took the planes 34 minutes to get to Mckean, arriving about 1904 Z. A reasonable estimate of the time spent over Mckean is 15 minutes meaning they departed at about 1919 Z to fly to Gardner. The course to Gardner is 200° T and the distance is 67 NM. On this course the planes had a bit of a tailwind bringing their ground speed up to 93 knots so it took them 43 minutes to reach Gardner arriving around 2002 Z.
They circled around that island for 18 to 28 minutes (your estimate Ric,) so departed Gardner as late as 2030 Z and you state that the tide level was two feet above the reef surface at that time so that it obscured the Bevington object.
I am confused by this. Robert Brandenburg, LT COMMANDER, USN (Ret.,) did a comprehensive study of the tide level at Gardner and compared those tide levels with the reception reports of radio transmissions believed to have come from the Electra sitting on the Gardner reef. By Commander Brandenburg's computation, the reef surface was 52 inches above the tide level datum used for tide information at the nearest island, Hull, and this is the tide information that Brandenburg used for his calculations. Brandenburg also computed that the water level would have to be 24 inches (2 feet) above the reef surface,
a total of 76 inches above the tide datum, before the water would interfere with the propeller tip and prevent running the engine.
See Commander Brandenburg's complete table of tide levels and radio transmissions. The first page lays out the computation of the height of the reef surface and makes it clear that a two foot, 24 inch, tide above the reef surface equals 76 inches using the Brandenburg notation.
Ric, you said the tide was high at the time of the Lambrecht flyover, 2000 Z ~ 2030 Z, being two feet above the reef surface, 76 inches above the tidal datum as calculated by Brandenburg. But, now taking a closer look at Commander Brandenburg's tide analysis, I see that he shows the height of the tide at 2100 Z on July 9th, only 30 minutes after the Lambrecht flight moved on, as 9 inches and going down to only 5 inches at 2130 Z. Commander Brandenburg's calculation shows that the tide went down only 4 inches in the half hour period from 2100 Z to 2130 Z so it is unlikely that the tide went down more than the same 4 inches in the previous half hour period from 2030 Z, the time of the flyover, and 2100 Z when the tide was down to 9 inches making it extremely unlikely tht the tide was higher than 13 inches at the time of the flyover. This is 63 inches (5 FEET and 3 inches) lower than your value of 76 inches. Even if the Bevington object was closer to the reef edge than your idea of where the Electra landed, Commander Brandenburg shows that the reef edge is 8 inches above the tidal datum so a tide of 13 inches is still only 5 inches higher than the reef edge and unable to hide the Bevington object even if the Bevington object was right at the edge of the reef. Due to the slope of the reef surface that Brandenburg determined to be 2.8 degrees, if the object was at least 8.5 feet in from the edge of the reef then there would be no water touching the object with the 13 inch height of tide that Brandenburg's computation shows existed at the time of the flyover. In fact, contrary to the tide being high at the time of the flyover it appears to be near the time of low tide. The Brandenburg report shows that the tide goes down to "zero" at 2230 Z, only two hours after the flyover. The change from high to low tide takes about six hours normally so it was much closer to low tide than it was to high tide at the time of the Lambrecht flyover.
Something does not compute or am I missing something Ric?
gl