Shoal (underwater)

“ Improvements were commenced, and matured as if by magic and no cloud was discernible in the business horizon, to dampen the ardor or cause the business man to look out for a cross sea. No one was fearful of shoals, as none were laid down in their charts; all forgetting, that, no matter how buoyant a sea, it always finds a shoal upon which to break. ”

“ The afternoon was spent in a lazy, lounging way; the shoal, if shoal it can be called, where the bottom was evidently jagged rock and the depth never less than twenty fathoms, lay just off the island where they were, and the boats had but to pull out a cable’s length to be in the very best of the ground; but it is not a very exciting amusement to be continually hauling in little fish about the size of whiting, as fast as the lines could run down. ”

“ Removal of Shoals.—The possibility of securing uniformity of depth in a river by the lowering of the shoals obstructing the channel depends upon the nature of the shoals. A soft shoal in the bed of a river is due to deposit from a diminution in velocity of flow, produced by a reduction in fall and by a widening of the channel, or to a loss in concentration of the scour of the main current in passing over from one concave bank to the next on the opposite side. ”

“ Indeed, the noise that they made by blowing and dashing of the sea with their tails, making it all of a breach and foam, was very dreadful to us, like the breach of the waves in very shoal-water, or among rocks. The shoal these whales were upon had a depth of water sufficient, no less than twenty fathom, as I said; and it lies in latitude 22° 22 ́. The shore was generally bold all along; we had met with no shoal at sea since the Abrohlo-shoal, when we first fell on the New Holland coast in the latitude of 28°, till yesterday in the afternoon, and this night. ”

“ They were distinctly seen under water, particularly a large white mass of rock, in 41/2 fathoms, having from 5 to 61/2 fathoms round it. The shoal was traced in 7 fathoms, on detached rocks, near the edge of it, having deeper water between them. On the southern edge of the shoal, from S.E. to W., the depth increases gradually to 30 fathoms, at the distance of half-a-mile from the shoalest part. ”

“ The last objects on the horizon line were white-crested breakers combing above the "gulf or ship-swallower" lying in wait beneath them. It is a dangerous sea, and Nantucket Shoals have obtained a terrible celebrity—unequaled, perhaps, even by the Goodwin Sands, that mariners shudder at the mention of. If a ship grounds on the Shoal she is speedily wrenched in pieces by the power of the surf. They will tell you of a brig (the Poinsett) that came ashore on the south side with her masts in her, apparently uninjured. Two days' pounding strewed the beach with her timbers. ”

“ There were no rocks to look out for, no shoals in what was really one vast shoal, and all was smooth as milk. All the afternoon, till the sun set and the stars came out and we dropped our anchor in a luminous nothingness, a child could have navigated us; but, when the next day brought us up to the northwest corner of Andros, we found ourselves face to face with a variety of difficulties: glimmering sandbars, reaches of moon-white shoals, patches of half-made land with pines struggling knee-deep in the tide ”

“ On the south side of the entrance, which is the deepest, there is ten feet at low water; and within side, the depth is from 2 to 4 fathoms in a channel near the south shore: the rest of the bay is mostly occupied by shoals, over which boats can scarcely pass when the tide is out. High water appeared to take place about seven hours after the moon's passage; at which time, a ship drawing not more than fourteen feet might venture in, if severely pressed. Shoal Bay is difficult to be found, except by its latitude, which is 29° 261⁄2′ ”

“ When I had got within about half a mile of the shoal, I rested upon my oars, and looked behind me, for in that direction lay the goal I was struggling to reach. I perceived at a glance that the little islet was quite out of the water, as if the tide was at its lowest; but the black stones were not visible on account of the birds that were standing or sitting all over them. It looked as if a flock of swans or white geese were resting upon the shoal ”

“ Wherever a shoal of sand exists in the offing, at a distance beyond where the ebbing of the tide recedes to its greatest extent, denominated low water mark, there the innermost shallow will probably be: another shoal immediately forms, the base commencing at low water mark, and a gradual rise takes place towards the cliffs, terminating at or beyond the extent of the flowing of the tide denominated high water mark. Here, then, the shoal will be more efficient; the tidal wave and current will be checked and broken against the ascending bank. ”

“ Shoal-fish, as a rule, are caught in greater quantities as they leave the Euxine, and at that season they are in the best condition. At the time of their entrance they are caught in very plump condition close to shore, but those are in comparatively poor condition that are caught farther out to sea. Very often, when the coly-mackerel and the mackerel are met by a south wind in their exit, there are better catches to the southward than in the neighbourhood of Byzantium. So much then for the phenomenon of migration of fishes. ”

“ The flying-fish swim in shoals, for on one day they are seen rising about, and in the vicinity of the ship, in great numbers; and on the day following, or latter part of the same day, only a few stragglers are seen. When disturbed by the passage of the ship through the shoal, they rise in numbers near the bows of the ship, and the consternation seems to spread among those far distant: the same may be observed when dolphins and albicores are pursuing them. ”

“ In daylight the danger is not nearly so great, because the north-eastern and north-western edges of the shoal are fringed by a number of cays among which the sea breaks heavily, while the whole surface of the shoal is white water. ”

“ It is followed by numbers of great ravenous fish, who devour quantities of the herrings, while above hover birds, as you have just seen, ready to pounce down on stragglers near the top. To escape these enemies, the shoal makes for the nearest shore, and seeks safety in those shallows where the large fish cannot follow. But here it meets with a third great enemy. It may escape from the fish, and elude the vigilance of sharp-sighted birds, but from the ingenuity of man it can find no escape. ”

“ On the middlemost shoal no rocks were uncovered; but on the south-east end of the Mermaid's Shoal several were observed. These reefs are of a coral formation, and are very dangerous to approach at night, from their vicinity being unfathomable to the depth of 170 fathoms; still, however, the surf that constantly breaks upon them may be heard at a great distance, and will generally be sufficient to warn the navigator of his danger.
March 23.
On the 23rd we passed the meridian of Cape Van Diemen, in latitude 10 degrees 48 minutes. The same evening some land was indistinctly seen bearing South. ”

“ Speaking in general terms of Shoal-water Bay, I do not conceive it to offer any advantages to ships which may not be had upon almost any other part of the coast; except that the tides rise higher, and in the winter season fish are more plentiful than further to the south. No fresh water was found, unless at a distance from the shore, and then only in small quantities. Pine trees are plentiful; but they grow upon the stony hills at a distance from the water side, and cannot be procured with any thing like the facility offered by Port Bowen. ”

“ We kept on still to the eastward, with an easy sail looking out sharp: for by the many signs we had I did expect that we were near the land. At 12 o'clock in the night I sounded and had 45 fathom, coarse sand and small white shells. I presently clapped on a wind and stood to the south, with the wind at west, because I thought we were to the south of a shoal called the Abrolhos (an appellative name for shoals as it seems to me) which in a chart I had of that coast is laid down in 27 degrees 28 minutes latitude stretching about 7 leagues into the sea. ”

“ Forsyth and myself started to explore the opening. We soon discovered that it was nothing more than a shallow creek at low-water. The tide here rising twenty feet, gave it the important appearance it had yesterday evening. A tall clump of naked trees was conspicuous at the east entrance point, towering above the insipid mangrove shore. We gave it the name of Hope Inlet, to commemorate the feelings it excited on its first discovery. From the south point of Clarence Strait it is distant eleven miles, and the bay in which it lies, from the shallow-water at the head of it, was called Shoal Bay. ”

“ The only practical question is whether to take the short cut between Bearse Shoal and Monomoy. It saves two or three miles, and if it’s going to be rotten weather it’ll be more comfortable for old men like us to get into some sheltered water before dark.”
“What is there against the short cut?”
“Well, if it should get thick with rain it would be a little hard to see where we were, and there are shoals on both sides; also it’s all so shoal there that a heavy squall from the northeast would kick up an infernal rip with the tide running the way it will be when we get there. ”

“ Fish which swim in shoals are not much produced in the rivers, but are bred in the lakes, and they do as follows:—When there comes upon them the desire to breed, they swim out in shoals towards the sea; and the males lead the way shedding forth their milt as they go, while the females, coming after and swallowing it up, from it become impregnated: and when they have become full of young in the sea they swim up back again, each shoal to its own haunts. ”

“ John Murray's explanation is fully confirmed that the coral reefs often begin on shoals; that these shoals are due to elevations of the sea-bottom; that the reef when once established can and does grow seaward upon its own fragments broken and submerged; that these form a "talus" capable of indefinite advance until the farthest limit of the shoal is reached; that the rearward ranks of the coral animals die as they are left behind in the hot and shallow waters of the lagoon ”

“ They come in great shoals; and they keep rooting the mud like hogs, and leave their trace in the form of large round holes.
They are very cunning; and when surrounded with a net, the whole shoal frequently escape by leaping over it; for if one takes the lead, the others are sure to follow. ”

“ They are formed by the deposit of particles of soil brought down into the main river by its tributaries, or by occasional streams created by the melting of the snow, or heavy rains. A shoal is first formed, which, as it accumulates, rises gradually above the ordinary surface, while the stream itself, if it flows like the Connecticut through a soft soil, is continually deepening its bed, and leaving these newly-formed banks out of the reach of accidental floods. ”

“ When the natives wish to use this net, they place it in a canoe, and look out for a shoal of fish. As soon as a favorable opportunity is found, the canoe is taken to seaward of the shoal, and let carefully into the water. Each end is taken in charge by one or two men, who bring the net round the shoal in semi-circular form, so as to enclose the fish. These men gradually approach each other, while another man beats the water with a pole, or flings stones into it, so as to frighten the fish into the enclosure. ”

“ A shoal extends from Great Banda towards the Gounung Api, leaving a deep passage of not more than a quarter of a mile wide. Upon this shoal, a considerable portion of which is dry at low-water, extensive bamboo fish-weirs are erected, which seem to be very productive. The natives also use fish-pots formed of bamboo, resembling in principle the common drum-net, which they leave down in shoal water during the night, and generally find a good supply in the morning. ”

“ Sometimes the water would deepen a little and relieve us; again it would shoal. Between the coral-branches we would sink at times to our necks in the slime and water, our limbs lacerated with the sharp projecting points. Fortunately, the wind helped us; keeping all sail on, thus for more than a hundred yards we toiled, until the water deepened and the reef was passed. Wet, foul, bleeding, with hardly strength enough to climb into the boat, we were safe at last for a time. As we cleared the shoal, the schooner hauled by the wind, and opened fire from a nine-or twelve-pounder ”

“ The middle shoal lies in 42° 56' north latitude and 68° 52' west longitude. From this the south shoal bears S. by E. and the north shoal NNE., each being 3 1/4 miles distant from it. The water breaks on these in rough weather and, though of small extent, they are dangerous to passing vessels bound from Cape Sable to Massachusetts ports, across whose course they lie directly. Except for these shoals, the water ranges from 15 to 60 fathoms. The ground is more or less broken, and the bottom is of sand, pebbles, and rocks.
The principal fishing on these grounds is for cod, haddock, hake, and cusk ”

“ The sea between Sooloo and Palawan, near the shoal coast of Borneo, is interspersed with irregular reefs and shoal patches; not coloured: but in the northern part of this sea, there are two low islets, Cagayanes and Cavilli, surrounded by extensive coral-reefs; the breakers round the latter (Horsburgh, vol. ii, p. 513) extend five or six miles from a sandbank, which forms the only dry part; these breakers are steep to outside ”