If the navigational logic is the "foundational" rationale for finding AE and FN on Gardner, then certainly the most compelling clues are Gallagher's reports and letters about finding the castaway site. These two are what have me believing that TIGHAR is on to something big.
Having said that, there's something odd with the story as it is currently presented...it just doesn't seem like normal human behavior for someone to land on the N/NW side of the island-with all of its associated landmarks-and trek down to the SE side, without any real ROI. Where's the utility?
If I can somehow put myself in their shoes, I think I would stay on the N side (after a quick recon loop of the island). There are a lot of landmarks that make this side pyschologically appealing.
A)First of all, that's where I landed. My plane-that I've spent so much time in-is there, even if it is submerged and being slowly torn apart by the tides.
B)The Norwich City is there...the primary symbol of civilization anywhere in my new world.
C)There are at least a few remains of the short-lived coconut plantation there; these signs of life might give me some comfort.
D) It's the "front-door" to the island: the primary entrance to the lagoon is here, the fringe reef is far enough away from the shore that I have a nice buffer of a comfort zone, and this whole side of the island is blunted distinctly from the rest of the island.
So I think I have some emotive reasons to stick around that side of the island.
And there are practical reasons for staying there as well:
A)Aside from the initial recon tour, why make the physical effort to go to the completely opposite end of the island, the furthest distance away from my plane?
B)Don't I want to try and "raid" the Norwich City for supplies? And if crabs and centipedes are such a problem, wouldn't I try and stay on the ship, if there was any way possible?
C)Wouldn't I try to raid the plantation for supplies as well, and what about the prevalence of coconuts on this side of the island?
D) Since the Norwich City is such a standout feature, wouldn't I expect other fliers-or anyone else coming near the island-to immediately focus on it? It seems the eye would naturally be drawn toward it; well then again why would I then walk as far away as possible from the first thing any search party or any other human would see?
As for the 7 Site itself, I don't really see what it gives me that I can't find in any other number of places on the island. It's on an incline, but so are whole stretches of Gardner. Yes, it's a narrow point between the lagoon and the ocean itself, but again there are several areas which don't seem to be that much larger. In fact, these things can be had, just a little further to the S, which is where the Coast Guard station was sited, after all. And I guess the reason the Guard station was located there was because it was on a point, and you could see a wide expanse of water, from two of the three sides of the island.
Isn't that odd? To be marooned, march not just five minutes, but several kilometers away from the built-in amenities of the N side, only to stop shy of a new position that would give you the best possible sweep of a search party in the surrounding seas and skies?
And all the bird/fish/turtle bones show that our castaway was quite ambulatory; it's not as if they were making a trek of the island, had an ankle injury and had to make-do on the spot.
Is there any possibility that they could have landed near the Seven Site? I'm not really proposing that, but I'm just trying to make sense of why someone would land on the N/NW side, and choose to camp at the Seven Site...