1 M or m â prefix designating a number in thousands (not to be confused with SI prefix M for mega-or m for milli).
There are two types commonly referred to as: 'Shallow' and 'Deep' water. The differences are not only in the Frequency but also in the Beam Width and they are as follows: 'Shallow' water HST-WSBL 106-72 Transducer will operate on 2 frequencies on the HDS models: 200 (20Â°) & 83KHz (60Â°). 'Deep' water HST-DFSBL 106-77 Transducer will operate on 2 frequencies on the HDS models: 200KHz (12Â°) & 50KHz (35Â°).
(400 m) is indicative of conditions in the deeper waters (hypolimnion) of Lake Tahoe. Since 1970 the deep water temperature has increased by approximately 1 Â°F (0.6 Â°C), at an annual rate of 0.021 Â°F (0.012 Â°C), a rate of warming slower than the surface water.