Sir Ralph Delavall served in the Restoration navy and into the reign of William III and Mary II. During 1666, he was lieutenant of the 3rd Rate Henrietta and then the 3rd Rate Cambridge. In 1668, he was lieutenant of the 4th Rate Tiger. In 1670, he was appointed as lieutenant of the 4th Rate Adventure. At the beginning of the third war, in 1672, he was lieutenant of the 4th Rate Advice. In 1673, he was appointed as captain of the 5th Rate Eagle. Then on 9 April 1677, the King appointed him as commander of the 4th Rate Constant Warwick. Finally, not long before the Glorious Revolution, he was appointed captain of the 3rd Rate York (on 1 October 1688) by King James II. This is from Pepys's papers in "Tanner".
Andrew found additional information about Sir Ralph Delavall. In 1688, he commanded the 3rd Rate York. In 1690, he was Vice-Admiral of the Blue. He was knighted in 1690. At the Battle of Beachy Head, he commanded the Rear. He served as president of the court martial that acquitted Lord Torrington of any wrongdoing during the Battle of Beachy Head. In 1692, he was was Vice-Admiral at the Battle of Barfleur. He was removed in 1693, as he was a Jacobite. From 1695 to 1698, he was member of parliament for Great Bedwin. Thanks to Andrew for the good information.