I am trying to solve the mystery of the exact circumstances of the sinking of the tanker R.P. RESOR off New Jersey on 26 February 1942. The matter ultimately hinges on two questions:
1.) Whether U-boats had any sort of running lights.
2.) Whether the U-578's captain, Ernst-August Rehwinkel, had any reason to falsify his log.

The accounts of the R.P. RESOR's sinking are highly consistent- mostly because they hinge on a single survivor's account (there were only two survivors, and the other was asleep below decks when the attack occurred.)

The crewman, John Forsdal, reported that he was standing watch on the RESOR's forecastle when he saw a darkened, low-lying object slowly approaching the tanker about 300 yards off the port side. The object emitted no engine noise and had no lights on. Suddenly, three lights turned on. Forsdal reported that the object- which he presumed to be a fishing boat- showed "a white light, centered about five feet atop a green light and a red light." (Note: whatever colors he recalled are of much lesser importance than the fact he claimed to distinctly remember lights turn on.) The lights then turned off a moment later. The boat was headed directly toward the RESOR's midships section, so Forsdal alerted the bridge and the tanker steered slightly to starboard to avoid a collision.

The torpedo hit the R.P. RESOR about 2-3 minutes later. The tanker went up like a torch, and only Forsdal and one of the Navy Armed Guard men survived. As Forsdal was abandoning ship, he recalled seeing the upper deck and conning tower of a U-boat about 500 yards away motoring toward shore.

This account of events has since become "the" account. Namely, that the U-boat's captain bluffed the R.P. Resor in order to approach to near point-blank distance. It's not a far-fetched conclusion.

Except that the log of the U-boat in question, U-578, tells a very different story:

20:45 EST, 26 Feb: "Ahead a vessel in sight with course 20° to 30°. Shortly
thereafter a second vessel bearing 340°T. Evaded 2 illuminated fishermen. First I pursue the ship ahead, that is furthest ahead in the direction of travel. I must hold far off in the bright moonlight, not maneuver ahead. In so doing determine that the ship is a large tanker...He proceeds on the 20-meter line on a northerly course. I offset to the east for surface attack at target angle 30° to course 230° against the moon and sea to range = 1200 meters."

[No entries were made between the aforementioned entry, at 20:45, and the following one, at 23:36.]

23:36 EST, 26 Feb: "During the torpedo run on the other side of the tanker there is an approaching light, apparently a destroyer or patrol vessel which was not seen before, probably just there by chance. (combat sketch, see torpedo firing
report) After 83 seconds 1 hit center, then immediately thereafter a very heavy explosion with an enormous tongue of flame. Tanker breaks in the middle and is immediately engulfed in flames from stem to stern, was therefore full, apparently gasoline."

NOTE: I have the torpedo firing reports, but the specific report for this incident is missing.

I don't think too much stock should be put in Forsdal's recollection, only because of how badly memory so often serves the survivors of such calamities. however, if there was indeed a third ship in the vicinity, then it is curious that no record seems to exist of anyone (whether a fisherman, a naval vessel,m or something else) reporting that they were in the immediate vicinity when the tanker exploded. It must be stressed that the R.P. Resor's fiery demise was literally seen from miles around.

What do you think? Do U-boats even have lights of the type that Forsdal described? Could Rehwinkel have deliberately omitted a particularly daring approach from his log? (This was his first-ever sinking despite being a decade older and a rank higher than most of his peers...perhaps he was desperate enough to try something really audacious.) Or was Forsdal just plain wrong, perhaps a victim of adrenaline-added false memories?