How to get better Bottom definition on a steep slope

[Anonymous]

Hi,

Set up is a FCV 295 connected to a R309,
I am struggling to get decent bottom definition when sounding up the side of a sea mount on 38khz.even in screen advance 1/1

Any tips?

Will attach pics of screen shot plus settings I am using

 

[Anonymous]

While I'm here I better just check I have the temp sender wired up correctly as support here is poor, using the white and brown wires in the airmar R309 ducer cable to a furuno plug

Brown to yellow
White to green

Has given me a bit of a funny water temp was about half of what it should have been

Will attach a pic

Thanks in advance!

 

[Snips]

Weapon,
Thanks for the screen shots. You mention that you are using a 1/1 screen advance but the menu indicates the 295 is set for 2/1. Also you are using a long pulse length. If you want to try different PL's, set the 295 into manual PL mode and shorten the PL. As far as your temperature input the color code depends on the cable you are using, if you are using a standard NMEA cable the color code is black (pin 2) and yellow (pin 3).

Snips

 

[Snips]

Weapon,
Also if you raise the frequency from 38 to 45Khz you will narrow up the beam width from 9x15 to 7x13.

Snips

 

[Anonymous]

Hi snips,
Thank you for your feed back. Oh yes must have got the pics mixed up.what I was getting at there was going down to 1/1 advance wasn't helping.

I will try shortening the pulse length this should improve definition yes?, just better mention that that depth scale is in meters.so the depths we are talking are 600m with the slope coming up to 300 odd m

Will get back out there and try 45khz and shortening pulse length and will take some more pics

 

[Anonymous]

Thanks temp all sorted!,
Now to shorten the pulse length
LF TX pulse change from long to manual
Then now I see you can adjust the pulse length it was set at 0.05msec when it was on long
Is that not as short as it will go?.the scale goes from 0.05msec through to 5msec or is it the other way around?

 

[Snips]

Weapon,
To be honest I don't know anybody that uses a long PL. Below is the target difference between STD (standard) and Short 1. This is from a test I did with the FCV-1200 showing the pulse length differences using an Oscilloscope. Another advantage of using a shorter PL is that the 295 will transmit faster.

Snips

 

[Anonymous]

Ok thanks,
Could you please quickly explain the difference between
Settings

TX pulse.
Pulse length ( msec )

In the pic I sent through I had TX pulse set at long
Then the pulse length was set at 0.05 msec.
Isn't 0. 05 msec the shortest pulse length you can set it to?
What am I missing here?.

Thanks again, really appreciate this feed back.

 

[Snips]

Weapon,
The shorter the PL the better the target separation. Look at the screen shot in my last post, with a Standard PL you see one fish target but with a shorter PL you see there are actually two.

Snips

 

[Snips]

Weapon,
Maybe it is easier to do it this way. Next time you go out just change the PL from Long to Short 1 and look at the difference. Just know that you will need to use more gain because you are not putting as much TX power into the water column.

Snips

 

[Anonymous]

Hi again,

I have spent slot of time playing with settings, trying pulse length short and by skewing the frequency up to 40 khz as wel as every other setting on the machine but the picture has improved slightly on the slopes but I am still not happy with it as it makes it very difficult to find fish hard on the bottom.

I think the only thing left to try is 45khz could you please advise on what tap setting to use?

Just thought I would mention I know people who are using the 295 on 28khz and 38khz on the same seamounts and are not having any problems with bottom definition.

Thank you!

 

[Snips]

Weapon,
Thanks for the comments. So if other vessels using 295's are can detect fish on the same slopes the two variables would be settings and transducers. Furuno's 28 & 38Khz transducers have wider beam widths than the R-309. For me it would be interesting to get on one of these other vessels to find out exactly what transducer they are using and their settings. The Tap setting 28-38Khz is "C" if you would like to try 45Khz I would suggest a Tap "B".

Snips