27:12-20 Those who launch forth on the ocean of this world, with a fair gale, know not what storms they may meet with; and therefore must not easily take it for granted that they have obtained their purpose. Let us never expect to be quite safe till we enter heaven. They saw neither sun nor stars for many days. Thus melancholy sometimes is the condition of the people of God as to their spiritual matters; they walk in darkness, and have no light. See what the wealth of this world is: though coveted as a blessing, the time may come when it will be a burden; not only too heavy to be carried safely, but heavy enough to sink him that has it. The children of this world can be prodigal of their goods for the saving their lives, yet are sparing of them in works of piety and charity, and in suffering for Christ. Any man will rather make shipwreck of his goods than of his life; but many rather make shipwreck of faith and a good conscience, than of their goods. The means the sailors used did not succeed; but when sinners give up all hope of saving themselves, they are prepared to understand God's word, and to trust in his mercy through Jesus Christ.
17. undergirding the ship—that is, passing four or five turns of a cable-laid rope round the hull or frame of the ship, to enable her to resist the violence of the seas, an operation rarely resorted to in modern seamanship.
fearing lest they should fall into the quicksands—"be cast ashore" or "stranded upon the Syrtis," the Syrtis Major, a gulf on the African coast, southwest of Crete, the dread of mariners, owing to its dangerous shoals.
sail—This cannot be the meaning, for to strike sail would have driven them directly towards the Syrtis. The meaning must be, "lowered the gear" (appurtenances of every kind); here, perhaps, referring to the lowering of the heavy mainyard with the sail attached to it [Smith].