Under 4m (for 600kHz and 1MHz) shallow water mode is engaged.

• Power level to Low-. This is to prevent saturation of the AST ping

Under 2m super shallow water mode is engaged.

• Power level to Low-
• Fixed AST window, surface detected when threshold is exceeded. Default is 80 counts but can be set by user.

Under 0.7m AST no longer functional. Switches to pressure.

Problems that can arise

• At >4m with High power (especially for 600kHz) AST saturation
• <4m with high sediments, may look like surface. AST count threshold reached, try increasing threshold
• For 600kHz in shallow water; gives unreasonably small orbital velocities, problem with determining direction.