Furuno 587- Bottom Thickness in LF

[TeamRezoned]

Good Morning,

This is my first time posting, but I have obtained a lot of great information from this forum and would like to thank all of you who contribute on a regular basis.

We have a 33T Contender and Furuno 587 paired with a Airmar B164 thru-hull transducer. Over the last year, we have been spending some time deep dropping in the northern Gulf of Mexico. We have had some success finding fish in 600+ feet, but I think we could have more success by changing the settings on our machine.

We typically run our machine in LF, zoomed in to 30' or 15' range because in our area we are mostly fishing flat hard bottom edges or very small rocks. In order to consistently mark fish that deep, we have to almost max out the gain on our machine. With the machine zoomed in that much and the gain set that high, the bottom return takes up almost half of the screen and we cannot see any differences between hard and soft bottom.

I have two questions:
1. Is there any way to adjust the LF bottom thickness so that we can see the "legs" and bottom thickness change when we travel over different types of bottom? I am hoping that we can adjust it so it reads similar to the way the machine reads on HF in shallower water.

2. When we are looking for deep bottom (300'+ & LF) in rough seas, we are constantly losing contact with the bottom if we are heading in to the waves. This does not happen when we are in rough water and looking shallower, running on HF. Are there any adjustments that can be made to keep this from happening?

Thanks in advance for any input or advice!

-Dan

 

[Snips]

TeamRezoned,
Welcome to the forum.
The length of the bottom tail is going to depend on your gain setting. Since fish targets are a weaker return than the bottom you need to adjust the gain accordingly to see them, which (as you have found) will produce a rather deep bottom tail. Unfortunately the 587 doesn't have a Bottom Discrimination Zoom mode like the FCV-295/1150. This would allow you to split the screen and let you view the tail of the bottom on the left side of the display. You may be fishing to deep for this idea to work but you can give it a try. Try using the second echo for bottom hardness, so if you are fishing in 400ft of water set the range to 900ft to see if you can see the second echo. Then by using the Marker Zoom mode you can zoom (expand) into any part of the water column where the fish are. Worth a try at least.
Your second question is an turbulence issue which is very common. The LF side is very susceptible to turbulence where the HF does a much better job. Even in calm conditions you probably noticed that the LF performance will degrade the faster the vessel is going. There is no setting that can over come this, the only thing that can be done is maybe relocating the transducer in a different location that has smoother water flow. Hope these answers help.

Snips

 

[TeamRezoned]

Snips,

Thank you for the detailed response. One thing that I failed to mention is that we have our gain turned WAAAY up (9 or 10), partly because we feel that setting paints the fish better. We can turn the gain up that much and we still have no real clutter on the screen. Maybe our clutter/noise/gain/TVG settings are not set to what they should be? If we were able to adjust the settings so the gain did not have to be set so high, maybe the bottom would be less thick under those settings? I am going down to the boat tomorrow and will try to remember to document the current settings on the machine.

-Dan

 

[Snips]

TeamRezoned,
The default settings on the Clutter is 0, Color Erase is 0 and the TVG is Medium. I like to use a Power setting of 10 (instead of Auto) and the TX Rate of 20. One thing you can do is to put the sounder into the demo mode and adjust the receive setting and watch the affect they have on the display. And as you have seen the B-164 (being a flush mounted transducer) is prone to turbulence which can hinder detection of fish targets. Do you have any screen shots you can post?

Snips

 

[TeamRezoned]

Snips,

I do not have any screen shots on my phone. I did check out settings over the weekend and this is how the machine is set up:

Interference- auto
Color Erase- 8%
Clutter- 70%
White line- 0%
TVG- High
Smoothing- off
TX power- auto
TX rate- 10

Could you please provide your thoughts on these settings? Our next trip will not be until this weekend and I will adjust the settings to your recommendations above, but we will not have another chance to get our deep for another month or so.

Thanks again for your help!

 

[Snips]

TeamRezoned,
Having the TVG (Time Varied Gain) setting on high increases the overall gain of the sounder maybe by 20%. Having the Clutter at 70% is suppressing any weak targets and affects how the tail of the bottom appears. If you need to use those settings you may want to think about using a most efficient transducer.

Snips