They cast four anchors - On account of the violence of the storm and waves, to make, if possible, the ship secure.
And wished for the day - To discern more accurately their situation and danger.

Cast four anchors out of the stern - By this time the storm must have been considerably abated; though the agitation of the sea could not have subsided much. The anchors were cast out of the stern to prevent the vessel from drifting ashore, as they found that, the farther they stood in, the shallower the water grew; therefore they dropped the anchor astern, as even one ship's length might be of much consequence.

Then fearing lest they should have fallen upon rocks,.... Or rough places, as shelves, rocks, or sands, as they might well fear, when the water shallowed so fast, from 20 to 15 fathoms:
they cast four anchors out of the stern; or hinder part of the ship; the Ethiopic version calls it, "the head of the ship": and adds, "where the governor sat"; that is, at the helm, to steer it. Perhaps the reason of this version is, because it is not usual in modern navigation, and so, when this version was made, to cast out anchors from the stern, but from the prow or head of the ship; but it seems this was done by the ancients. According to Pliny, the Tyrrhenians first invented the anchor; though Pausanias ascribes the invention of it to Midas, the son of Gordius: the most ancient ones were made of stone, as was the anchor of the Argonautes; afterwards they were made of wood; and it is said, that the Japanese use wooden anchors now; and these were not pointed, but had great weights of lead, or baskets filled with stones at the head of them, to stop the ship with; last of all they were made of iron, but with a barb or tooth on one side only, not on both: the anchor with two teeth or barbs was found out by Eupalamius; or, as others say, by Anacharsis, the Scythian philosopher: it was usual to have more anchors than one in every ship, of which there was one which exceeded the rest, both in size and strength, and was called the "sacred" anchor; and which was only used in case of necessity (t); and is what is now called "the sheet anchor". The modern anchor is a large strong piece of iron, crooked at one end, and formed into two barbs, resembling a hook, fastened at the other end by a cable. The parts of an anchor are,
1) the ring into which the cable is fastened;
2) the beam, or shank, which is the longest part of the anchor;
3) the arm, which is that which runs down into the ground; at the end of which is,
4) the flouke or fluke, by some called the palm, being that broad and picked part with its barbs like an arrowhead, which fastens into the ground;
5) the stock, a piece of wood, fastened to the beam near the ring, serving to guide the fluke, so that it may fall right, and fix in the ground.
There are three kinds of anchors commonly used, the kedger, the grapnel, and the stream anchor (u); yea, I find that there are four kinds of anchors, the sheet anchor, best bower, small bower, and stream anchor: it seems the grapnel is chiefly for the long boat: here were four anchors, but very likely all of a sort, or, however, not diversified in the manner the modern ones are. These they cast out to stop the ship, and keep it steady, and that it might proceed no further, till they could learn whereabout they were:
and wished for the day; that by the light of it they might see whether they were near land, or in danger of rocks and shelves, as they imagined.
(t) Scheffer. de Militia Navali Veterum, l. 2. c. 5. p. 147, 148, 149. (u) Chambers's Cyclopaedia in the word "Anchor".

they cast four anchors out of the stern--The ordinary way was to cast the anchor, as now, from the bow: but ancient ships, built with both ends alike, were fitted with hawseholes in the stern, so that in case of need they could anchor either way. And when the fear was, as here, that they might fall on the rocks to leeward, and the intention was to run the ship ashore as soon as daylight enabled them to fix upon a safe spot, the very best thing they could do was to anchor by the stern [SMITH]. In stormy weather two anchors were used, and we have instances of four being employed, as here.
and wished--"anxiously" or "devoutly wished."
for day--the remark this of one present, and with all his shipmates alive to the horrors of their condition. "The ship might go down at her anchors, or the coast to leeward might be iron-bound, affording no beach on which they could land with safety. Hence their anxious longing for day, and the ungenerous but natural attempt, not peculiar to ancient times, of the seamen to save their own lives by taking to the boat" [SMITH].