Topic: Recording Speeds

[Bayou Basser]

There has been some really good discussion lately about sensitivity and si range settings when recording.  I would like to hear from some of you about scroll speed while recording. 

Since my 899 transducer is on the transom I like to idle along as slow as possible while recording.  This way I can keep the boat in a very straight line to keep distortion to a minimum.  Now as far as scroll speed I've tried setting it about the same as gps speed (for example:#2 setting on unit if I'm traveling 2 mph).  When I do this trees and other above water objects don't appear on the screen until I am well past them.  I don't know if this matters or not.

If  I am recording along the shore line I've tried matching scroll speed to my relative rate of travel.  In other words I watch the terrain and objects as I past by them and try to match this with scroll speed.  I did this recently and got some good recordings.

So, lets get some really good input here.

Bayou Basser

[rnvinc]

It is normal for items in the SI image to show on the display "after" you have already passed them ...Regardless of Chart Speed ...

The SI beams are 90° to your boat path ... Meaning echo targets are not even in the SI beam until the target is 90° from the xducer "forward/aft axis" ...

Only the very first top horizontal row of pixels is actually "live" and what's in the SI beam ... Everything below this top row of pixels is "history" that you have already passed ...

The higher chart speed is just "scooting" the SI history (horizontal pixel row #2 and below) down quicker where your eyes can pick it up quicker ...

Chart speed matching boat speed is a common consensus to get SI images that display structure in "perspective" to their actual size ...

Slower chart speed than boat speed "compresses" the echoes being "painted" into the SI image ... And makes the echoes displayed shorter vertically ...

Faster chart speed than boat speed "elongates" the echoes being "painted" into the SI image ... And makes echoes displayed longer vertically ...
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On a different note of recording ...
 
I turn off the 83kHz 2d beam when recording to make the recording file size more manageable ...

I always keep the SI Enhance menu overlayed onto the SI image where I can make instant adjustments to the SI Sensitivity as the bottom depth/composition changes ... Even when recording ...

Rickie

[Bayou Basser]

With that said Ricky what do think about matching scroll speed with speed relative to passing objects? Do you think this would give a good recording?

Also I never thought about turning 83KHz off.  Thanks for that tip.

BB

[rnvinc]

The only time I set my Chart speed higher than my boat speed is if I am looking specifically for individual fish echoes (like you would find on beds) ...

This higher chart speed will elongate the fish echoes to make them more Visable in the SI image ...

If I'm recording ... I want all structure and bottom detail to be in "perspective" to its actual underwater size ...

Therefore matching chart speed/boat speed ...

Rickie

[rnvinc]

A good test is finding sunken tires and scan them repeatedly with different chart speeds to see how the chart speed affects an "otherwise round object" ...

Rickie

[Bayou Basser]

That's a very good suggestion since you know what a tire should look like.  The weather here in NE Louisiana has been much colder than normal.  By mid Feb the bass have come shallow and are very active but the water temp is still too cold.  I think next week I'll go out and just "play" with the unit.

I think they should shoot the ground hog next year so he won't see his shadow.  LOL.

Thanks for the feed back.  BB

[sonar2000]

Don't forget the rat in Raleigh, NC said it would be an early spring.

Sonar settings are basic set up to get you started and then you will spend much time with using the sonar ( and less fishing) until you get to understand the product. Going (scanning) known objects with different settings, scanning unknown areas until you get to know the normal display of a given bottom or structure and changing settings until you really get to know your products capabilities and functions. I really believe you should have a fishing buddy who runs the sonar and tells you where to fish.   
While most units will power on out of the box, it is a device that requires a lot of time to understand and make do for you what you want...
Chuck

[Bayou Basser]

Thanks Chuck and Rickie for the info.  We should get a break in the weather next week and I'll dedicate one day to tinkering with adjustments and recording.

I may sink an old tire (I'll tie a rope to it and drag it out - don't want to pollute the lake) and play with the settings as Rickie suggested.

Can't trust ground hogs or rats these days.

BB