dead low water

It was dead low water now, and the ship was heeled at an angle, the propeller showing clean.

From "Rebecca" by Daphne du Maurier

A boat would just float there comfortably I supposed, at dead low water.

From "Rebecca" by Daphne du Maurier

For when she recovered her senses it was bright sunlight and dead low water.

From The Luck of Roaring Camp and Other Tales With Condensed Novels, Spanish and American Legends, and Earlier Papers by Harte, Bret

May 30th.—The river Pei-ho is about 150 yards wide at its mouth, and at dead low water varies from 1 1⁄2 to 4 1⁄2 fathoms in depth.

From Narrative of the Circumnavigation of the Globe by the Austrian Frigate Novara, Volume II (Commodore B. Von Wullerstorf-Urbair,) Undertaken by Order of the Imperial Government in the Years 1857, 1858, & 1859, Under the Immediate Auspices of His I. and R. Highness the Archduke Ferdinand Maximilian, Commander-In-Chief of the Austrian Navy. by Scherzer, Karl Ritter von

We found that it was dead low water, and that the yacht had receded so much below the level of the quay, that no plank within reach would touch her. 

From The Handbook to the Rivers and Broads of Norfolk & Suffolk by Davies, G. Christopher