Captain Bruce of the Harlow reported that he first noticed smoke from the Waratah astern at 5.30 pm, 27 July. Where could this have been?
The Harlow would have been roughly abeam of Mpande River mouth and the Waratah abeam of the Umtata River mouth. See image below. (Placemark represents the Nkadusweni River mouth). The Waratah was roughly 11.25 n miles astern of the Harlow at this time.
The million dollar question is: where did the Waratah come about?
If we take into consideration 8.5 hours separated the last sighting of the Waratah by the Clan MacIntyre (Bashee River) and the first sighting by the Harlow (Umtata River), and lose about half an hour coming about, we can use:
8 hours x average speed of 13.9 knots (14.4 knots down coast and 13.5 knots up coast) = 111.6 n miles.
Subtract distance between Bashee River and Umtata River = 22.7 n miles.
88.9 n miles divided by 2 = 44.45 n miles southwest of the Bashee River, which places us roughly abeam of the Kei River mouth, 11 n miles out from shore.
Under these circumstances the Waratah would have been 6.49 n miles further out than the Clan MacIntyre (4.62 n miles out from shore).
Given the Waratah's final position (according to Captain Bruce's coordinates at 8 pm), Captain Ilbery probably held a return course 7.6 n miles out from shore. The crew of the Harlow never saw the starboard green light.
Assuming that the Waratah would have been about 11 n miles out from shore abeam of the Kei River mouth, notice how the Continental Shelf increases dramatically towards East London at this point, explaining the Waratah's position so far out.
The Harlow sighted smoke from the Waratah when she was abeam the Mpande River mouth and the Waratah abeam of the Umtata River mouth. This was 5.30 pm. Sunset at this location, 27 July, occurs at 5.26 pm. This implies that watchers onshore might not have noticed the Waratah 7.6 n miles out tracking up the coast. This also left only a narrow window of 2.5 hours for the chances of a steamer heading down the coast to sight her.
For an observer on the ground with eye level at h = 5 ft 7 in (1.70 m), the horizon is at a distance of 2.9 miles (4.7 km). For an observer standing on a hill or tower 100 feet(30 m) in height, the horizon is at a distance of 12.2 miles (19.6 km).
From this it is clear that unless watchers onshore had an adequate elevation, they would not have seen the Waratah 7.6 n (8.7 std) miles out. significantly narrowing the chances of random watchers on cliff tops observing the horizon out to sea.
But there was a mounted policeman who alleged he saw the Waratah, heading up the coast, founder. This might very well have been possible given the above, but let us not forget that it was dark and he would have to have relied on lights from the flagship to determine what he had seen.
I shall return to the identity of the mounted policeman in coming posts.