Piling and pier inspection apparatus and method

A method of determining the nature of a scoured underwater bottom area adjacent to a structure submerged in a current of rapidly moving water during a flood condition, said method comprising the steps of:

• (a) temporarily supporting sonar beam transducer means at least at a first underwater location within sonar beam range of said scoured area, wherein said transducer means is supported by a body which is suspended underwater by means located above the water surface, said body including a laterally extending delta-shaped wing member on each side of said body, which wing tapers inwardly toward an end of said body that faces upstream in said current of water and where each said wing has a trailing edge which laterally slopes downwardly from said body at an angle with the horizontal so as to form an inverted dihedral angle between said wing and said body;
• (b) scanning a first portion of said scoured area with a sonar beam from said first underwater location by sweeping said sonar beam through an angle in a first substantially vertical scan plane that points in a first azimuth direction from said first underwater location, so as to generate signals indicative of the range and bearing of said scanned first portion from said transducer means at said first underwater location;
• and
• (c) scanning at least a second different portion of said scoured area with a sonar beam from said first underwater location by sweeping said sonar beam through an angle in a second different substantially vertical scan plane that points in a second different azimuth direction from said first underwater location, so as to generate signals indicative of the range and bearing of said scanned second portion from said transducer means at said first underwater location.