I am enjoying learning how to use Reef Master2 program and see how it should help me locate prime areas to fish and catch more fish. I do have some questions.

1. In the sonar view, there are primary and secondary sonar windows. I have an Airmar B75C-20-H-9N CHIRP transducer covering the frequencies from 130 – 210 kHz on a Simrad NSS EVO3 MFD. What are the frequencies for the primary and secondary sonar windows with my equipment?

2. When making a map of the sonar track with that transducer, which frequency is used if the unit is set on CHIRP 130-210°?

3. I have the option of using this transducer in the CHIRP mode or at a fixed 200 kHz setting. Which of these two modes would give me better bottom resolution in the charts?

4. The option in the map setting to set up a grid to guide future tracks over an area of interest looks very useful. My transducer has a beam width 9° – 15°. When I measured distance covered by a single path of the boat on maps, it looks like the width is approximately equal to the water depth. Is there a formula or rule of thumb of how close passes should be to get an optimal map recording of bottom features?

5. Will running a rectilinear sonar scan on the north-south and east-west directions over an area give a better scan than just a single direction?

6. Some of the depth numbers are sideways or upside down on a chart made from several tracks. I assume it's from tracks with different headings. Is there a way to get all depth numbers to read from the N up orientation?

Sorry for the late reply on this one - I was hoping someone with more CHIRP knowledge than I would step in, but I will give it a go:

1/2. I'm not familiar with this transducer, but a search suggests that this is a high-frequency only transducer, so you'll be getting a primary channel but no secondary. CHIRP doesn't just use a single frequency, but sweeps across a the range of specified frequencies, in this case 130-210kHz.

3. Hard to say. The cone angle for this transducer is listed at 9-15 degrees, which is fairly narrow. You'll probably get good precision on depth at the expense of coverage. I would consult the documentation of this transducer to see what the effective cone angle is at the fixed/CHIRP settings.

4. Again. this is really hard to comment on. For many mapping situations, comprehesive coverage of the surveyed area (i.e. covering the entire bed with the transducer) is impractical, so you have to decide how close you want to space your runs - perhaps closer in areas with more bottom variation, and further apart in less interesting areas. I would say, though, that your calculation seems off for this transducer, which is probably covering an area more like a quarter of your depth. Take a look at Airmar's bottom coverage calculator here: www.airmar.com/bottom-calculator.html

5. Yes, it is a good idea to record in multiple orientations because of the way the interpolation works. In particular you will get better definition on any sudden depth changes if you can approach them close to perpendicular, and running multiple angles increases your chances of doing this.

6. This is a current limitation within RM and we have had a few requests to change it - it is on the list!

When reviewing the sonar logs, sometimes I get a primary and secondary channel and other times only a primary. I suspect if I am recording in trip mode, I get both primary and secondary. Sometimes I forget to switch over from 200 kHz to chirp after running and arriving at my fishing spot and I suspect with the single frequency 200 kHz, I only get a primary view in reef master. The next time I'm on the boat, I will test this theory and report back.

Thanks for the information. After I get a better handle on the basic program, I plan on adding the side scan module. I have found side scan to be very helpful at identifying lime rock areas. I fish in the Northeastern Gulf of Mexico and grouper are one of my primary species. Gag grouper tend to be found more frequently on vertical relief, for example a 3 foot area of vertical relief with flat surroundings. Red grouper are more commonly found on flat limerock areas with lots of cracks and crevices. The side scan signal is very good at detecting flat lime rock and being able to piece together multiple paths outside scan will be very useful.