Disclosed is an apparatus and method for improving the detection of signals obscured by either correlated Gaussian or non-Gaussian noise plus additive white noise. The housing has first and second surfaces and a least one side extending between said first and second surface. The guide has a first guide portion and a second guide portion of different diameters forming a guide portion step. When a vessel is under way at high speeds, the transom is subjected to the least up and down motion, and the bow to the greatest motion. Here, the plunger is designed to contact an active surface of the first locking element in the operating position and to contact an active surface of the second locking element in the rest position.