A DETAILED VIEW

Taking a closer look at personal bathymetric generators

- MIKE JACKSON

Remember as a kid when you put mask on and looked under the water for the first time? The difference in what you saw was like night and day once you had a clear view of what was beneath the water's surface. Similarly, personal bathymetric generators do the same for today's serious offshore fisherman. The advantage with PBGS is that you are recording the detailed bottom conditions of your specific fishing area into a high-resolution image. You may then utilize your own prerecorded PBGs on your chart plotter.

SWATH MAPPING BEGINS 

Here in the contiguous US, coastal cartography is available to recreational users, which includes some underwater topography. Swath mapping was developed in the 1970s, but the level of detail was not as high as today's technology allows. Today, with the increase in data points up to 50 channels per swath or pass over an area, these PBGS are in 3D and are exponentially more detailed than ever before. We have come a long way from the first recorded evidence of water-depth measurements, which were taken in ancient Egypt more than 3,000 years ago.

Generating PBGs is an option for a few different manufacturers, but in this example, let's consider that we are using Furuno's TZtouch3 and, more specifically, its B165 family of multibeam sonar transducers with the DFF-3D echo sounder. Each time the transducer ends a ping, it records data points in a 120-degree-wide beam. The term multibeam means that with the B165T, each ping records 50 individual data points, using the multiple echo returns to build your own personal bottom maps in extremely high resolution. The quality of detail in these PBG recordings is so high that you will probably find structure not shown on other maps or other forms of cartography, and it's also right in your own fishing areas.