"WHOEVER WILL CALL ON THE NAME OF THE LORD WILL BE SAVED." Romans 10:13
For judgment without mercy to him that hath not done mercy. And mercy exalteth itself above judgment. James 2:13
Bishop Williamson in a sermon on you tube clearly indicates that the flood caused many people to be saved because as they were dying they called out to God for mercy.
This perfectly agrees with Haydock's commentary on 1 Peter 1:19,20
19 In which also coming he preached to those spirits that were in prison:
20 Which had been some time incredulous, when they waited for the patience of God in the days of Noe, when the ark was a building: wherein a few, that is, eight souls, were saved by water.
In which (to wit, soul or spirit) also he came, and preached to those spirits who were in prison. The true and common interpretation of this place seems to be, that the soul of Christ, after the separation from the body and before the resurrection, descended to a place in the interior parts of the earth, called hell in that which we call the apostles' creed, (sometimes called Abraham's bosom, sometimes Limbus Patrum, a place where were detained all the souls of the patriarchs, prophets, and just men, as it were in prison) and preached to these spirits in this prison; i.e. brought them this happy news, that he who was their Redeemer was now come to be their deliverer, and that at his glorious ascension they should enter with him into heaven, where none could enter before our Redeemer, who opened as it were heaven's gates.
Among these were many who had been formerly at first incredulous in the time of Noe, who would not take warning from his preparing and building the ark, but it may be reasonably supposed that many of them repented of their sins when they saw the danger approaching, and before they perished by the waters of the deluge, so that they died at least not guilty of eternal damnation; because, though they were sinners, yet they worshipped the true God, for we do not find any proofs of idolatry before the deluge. These then, and all the souls of the just, Christ descended to free from their captivity, from their prison, and to lead them at his ascension triumphant with him into heaven.