Getting the Most out of your Lowrance DSI Unit

[Fishton]

Contrast and Surface Clarity:

Unlike conventional 200/83kHz sonar that has the old traditional sensitivity and Colorline control, the DSI merely has 'Adjust' (Contrast in %).  Now if you were to head out with your unit fresh out of the box and you turned the unit on in 30ft of water or more, and you immediately passed over a great big submerged tree while drifting over it with a light breeze pushing you – you will be absolutely blown away by what you see on the screen.

But! ... If you are in shallow water you will be very disappointed on the default settings, especially on a trolling motor mount, because the screen will appear to be very cluttered.  And when you try turning the contrast down to eliminate this clutter, you will lose ALL definition and render the unit useless and leave you wanting to get your money back.  Don't feel bad, first time Porsche owners experience the same buyer's remorse, until they learn the old trick of 'easy in and hard out'.

So what is the trick to 'easy in and hard out' with a DSI?  Simple ... 800kHz and increasing the Surface Clarity.  This feature plays a significant part in maintaining a strong definition as well as contrast while reducing clutter at the same time.

Default setting is Low.  If you are going to be fishing >50ft you could actually set it to Off.  But as you start moving into the <15ft depth you will need to change to Low or even Medium depending on water conditions.  And for very shallow conditions – High.  But this is not all that you can do to sharpen your image up ... Frequency.



Frequency:

Default frequency is 455kHz, but it does not like very shallow water.  Select the 800kHz which will allow you to go shallower maintaining a higher spatial resolution as well as contrast.  Alternatively select the split screen dual frequency view.  This will give you the wider 55° coverage area of the 455kHz, as well as the sharp high resolution of the 800kHz but with a smaller 30° coverage area.  Play around with your contrast in these individual frequencies around the 60% margin.



Transducer installation:

The installation of the transducer is also going to play a big role in the quality of your DSI image. 

Trolling Motor Mount:



Installing the transducer on the trolling motor has one major disadvantage ... it pivots!  Continuous course correction while passing over a POI will give a very distorted image.  The reason for this is that the sound wave is in the shape of a beam, and not of a cone like that of the traditional 200/83/50kHz.  This is especially of concern when using the wide beam of the 455kHz.

The solution to this problem is to approach your POI from a windward position and set a straight course before actually reaching the POI, and keeping the trolling motor pointed directly forward.  Do NOT turn the trolling motor while passing over the POI and split the screen to 455/800kHz for best results.

[bassn1]

Fishton, Great tips. Are the tips provided good for both the chart plotter and the grayline dsi? Not sure which I am going to purchase yet. I would like the chartplotter, however. the $599 VS $299 is going to be the final factor.

[Fishton]

Hi bassn1, the Mark (mono) unit is very similar in setup and guidelines.

[bassn1]

Yep. That's the one. Thanks

[coldfront]

Fishton,

great tip...and I'm betting it also applies to the HB products for those who have 'them'...

how does surface clarity setting play a role in the side imaging?  what 'tricks/tips' are available for the side imaging that can have similar 'value' to the operator?

If I haven't said this, I appreciate the heck out of you and how willingly share to help all of us...between you and 'Doc' there's a lot of great, useful, easily understood info available to us 'average' anglers...stuff that's applicable regardless of which unit is 'used'... 

[Fishton]

Hi coldfront,

We are only expecting to see the HB DI units here in South Africa late 2011, so I will not be able to make any comments until such time that I can get my hands on one for a full review.

Surface Clarity on an HDS StructureScan is usually set to Low, and never gets changed.

Thanks for the kind words.

John

[Haledamage]

Thanks Fishton,
The documentation from Lowrance on the DSI really bad.
I have had 4 Lowrance unit before..All had super doc's before.
Can't wait to get my DSI on the water.
Rick

[Fishton]

Hi Rick,

I agree, the user manual is a bit of a shocker.  That is what motivated me to write this article.  I have a few more handy little tricks to write about using the DSI.

[egolfer]

I just mounted the DSI to the front of my boat to put on the tolling motor.  The mount seems a little loose.  I know it pivot and swivels, but it just has more wiggle then the old Eagle500C I had there.  The Eagle had zero movement. 

Should I take it off in rough water?  And towing down the road?

[ArFisher]

Fishton

When are you going to be posting more tips with this unit. I just had one put in. And I am now looking for any tips I can get. I have never fully learned how to use my sonar to its fullest. And I hope I can do that with this unit. Thanks