The sinking ship effect has been determined to be due to various causes:
It has been determined that at times the sinking ship effect is caused by bulges on the surface of the ocean.
Lack of Optical Resolution
The sinking ship effect can sometimes be caused by a lack of optical resolution whereby elements of the hull can seem to merge into the sea. This can be reversed with optical magnification.
At other times the sinking ship cannot be reversed with optical magnification. In these cases the cause of the sinking effect is seen to be related to the common inferior mirage which regularly occurs for long periods of time over the surface of water. Over a period of time this sinking effect will disappear, revealing distant bodies.
It has been found that the Sinking Ship effect is inconsistent. At times it occurs and at other times it does not occur.
In The Plane Truth: The History of the Flat Earth Movement by Robert Schadewald we find:
“ Let Richard A. Proctor, science writer, astronomer, and good-humored arch-enemy of Parallax, describe another experiment:
' Mr. Rowbotham did a very bold thing … at Plymouth. He undertook to prove, by observations made with a telescope upon the Eddystone Lighthouse from the Hoe and from the beach, that the surface of the water is flat. From the beach, usually only the lantern can be seen. From the Hoe, the whole of the lighthouse is visible under favourable conditions. Duly on the morning appointed, Mr. Rowbotham appeared. From the Hoe a telescope was directed towards the lighthouse, which was well seen, the morning being calm and still and tolerably clear. On descending to the beach it was found that, instead of the whole lantern being visible as usual, only half could be seen—a circumstance doubtless due to the fact that the Air’s refractive power, which usually diminishes the dip due to the earth’s curvature by about one-sixth part, was less efficient that morning than usual. The effect of the peculiarity was manifestly unfavourable to Mr. Rowbotham’s theory. The curvature of the earth produced a greater difference than usual between the appearance of a distant object as seen from a certain low station (though still the difference fell short of that of which would be shown if there were no error). But Parallax claimed the peculiarity observable that morning as an argument in favour of his flat earth. It is manifest, he said, “that there is something wrong about the accepted theory; for it tells us that some much less of the lighthouse should be seen from the beach than from the Hoe, whereas still less was seen.” And many of the Plymouth folk went away from the Hoe that morning, and from the second lecture, in which Parallax triumphantly quoted the results of the observation, with the feeling which had been expressed seven years before in the Leicester Advertiser, that "some of the most important conclusions of modern astronomy had been seriously invalidated." [ref. 1.20] ' ”
From p.223 in Earth Not a Globe we read:
“ It is well known that even on lakes of small dimensions and also on canals, when high winds prevail for some time in the same direction, the ordinary ripple is converted into comparatively large waves. On the "Bedford Canal," during the windy season, the water is raised into undulations so high, that through a powerful telescope at an elevation of 8 inches, a boat two or three miles away will be invisible; but at other times, through the same telescope the same kind of boat may be seen at a distance of six or eight miles.
During very fine weather when the water has been calm for some days and become as it were settled down, persons are often able to see with the naked eye from Dover the coast of France, and a steamer has been traced all the way across the channel. At other times when the winds are very high, and a heavy swell prevails, the coast is invisible, and the steamers cannot be traced the whole distance from the same altitude, even with a good telescope.
Instances could be greatly multiplied, but already more evidence has been given than the subject really requires, to prove that when a telescope does not restore the hull of a distant vessel it is owing to a purely special and local cause. ”
On p.217 we read additional accounts of inconsistency:
“ In May, 1864, the author, with several gentlemen who bad attended his lectures at Gosport, made a number of observations on the "Nab" light-ship, from the landing stairs of the Victoria Pier, at Portsmouth. From an elevation of thirty-two inches above the water, when it was very calm, the greater part of the hull of the light vessel was, through a good telescope, plainly visible. But on other occasions, when the water was much disturbed, no portion of the hull could be seen from the same elevation, and with the same or even a more powerful telescope. At other times, when the water was more or less calm, only a small portion of the hull, and sometimes the upper part of the bulwarks only, could be seen. These observations not only prove that the distance at which objects at sea can be seen by a powerful telescope depends greatly on the state of the water, but they furnish a strong argument against rotundity. The "Nab" light-ship is eight statute miles from the Victoria pier, and allowing thirty-two inches for the altitude of the observers, and ten feet for the height of the bulwarks above the water line, we find that even if the water were perfectly smooth and stationary, the top of the hull should at all times be fourteen feet below the horizon. Many observations similar to the above have been made on the north-west light-ship, in Liverpool Bay and on light-vessels in various parts of the sea round; Great Britain and Ireland.
It is a well known fact that the light of Eddystone lighthouse is often plainly visible from the beach in Plymouth Sound, and sometimes, when the sea is very calm, persons sitting in ordinary rowing boats can see the light distinctly from that part of the Sound which will allow the line of sight to pass between "Drake's Island" and the. western end of the Breakwater. The distance is fourteen statute miles. In the tables published by the Admiralty, and also by calculation according to the supposed rotundity of the earth, the light is stated to be visible thirteen nautical or over fifteen statute miles, yet often at the same distance, and in rough weather, not only is the light not visible but in the day time the top of the vane which surmounts the lantern, and which is nearly twenty feet higher than the centre of the reflectors or the focus of the light, is out of sight.
A remarkable instance of this is given in the Western Daily Mercury, of October 25th, 1864. After lectures by the author at the Plymouth Athenæum and the Devonport Mechanics' Institute, a committee was formed for the purpose of making experiments on this subject, and on the general question of the earth's form. A report and the names of the committee were published in the Journal above referred to; from which the following extract is made.
- "OBSERVATION 6TH.--On the beach, at five feet from the water level, the Eddystone was entirely out of sight."
At any time when the sea is calm and the weather clear, the light of the Eddystone may be seen from an elevation of five feet above the water level; and according to the Admiralty directions, it "maybe seen thirteen nautical (or fifteen statute), miles," 1 or one mile further away than the position of the observers on the above-named occasion; yet, on that occasion, and at a distance of only fourteen statute miles, notwithstanding that it was a very fine autumn day, and a clear background existed, not only was the lantern, which is 80 feet high, not visible, but the top of the vane, which is 100 feet above the foundation, was, as stated in the report "entirely out of sight." There was, however, a considerable "swell" in the sea beyond the breakwater.
That vessels, lighthouses, light-ships, buoys, signals, and other known and fixed objects are sometimes more distinctly seen than at other times, and are often, from the same common elevation, entirely out of sight when the sea is rough, cannot be denied or doubted by any one of experience in nautical matters. ”
Indeed, modern time-lapse photography has verified that the sinking effect is inconsistent. See: Sinking Ship Effect Caused by Refraction