Fish Finder Questions

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Well-known member
Feb 23, 2006
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Isle of Palms, SC/Fairfax, VA
I do not like dual purpose units for gps and sonar unless the screen is HUGE, and me getting one of those units is remote at best. So I bought a new stand alone D/F color fish finder with speed and temp. Here's the question that I can only find bits and pieces of answers on the web.

Can I still use the dual purpose FF? Will the two 'ducers interfere with each other if they are both on the transom?

On my bass boat I have two, one on the trolling motor and one on the transom. They don't interfere.

Can I just set the old one to 50MHZ?

Is mounting the new 'ducer on the port side enough seperation?

Are there any other questions that I don't know exist?

You can see why the flexability would be great. And no the older black and white DP unit is not network compatable or I wouldn't be asking these questions and no, Alice will not let me get a new nav unit! :roll: Already asked. :)

Some people get away with same frequency. Have a friend as an example with a 32' non-Parker and he does OK. I bought a digital sounder last year but my first sounder was an oddball 120kHz unit so wasn't an issue.

But I also have a digital numerical display sounder as redundancy for awhile that is also 200kHz and I sometimes have it on at the same time. I don't run it always and I've tested it versus my new 50/200kHz unit.

Note, some sounders won't let you manually choose the frequency in dual frequency units and some will.

It is easy to test whether you get false readings.

Rangerdog, sorry I remembered you had two distinct questions.

Clockwise rotating props drive the recommendation on single screw setups to mount the transducer on the starboard side, to minimize bubbling affecting the transucer on the port side.

If the transom is wide enough and the hull depth is good it is minimized. Twin screws avoid mounts in between them.

I have my original 120kHz transducer (Apelco 530 finder/GPS plotter) mounted on the right side farthest from the prop and I mounted a Raymarine beside it last year closer in to the prop (DS600X, dual freq 50/200 kHz).

I have the backup digital display transducer mounted as a hockey puck in the bilge (Uniden 200kHz display to 200').

warthog5":1r59ko8t said:
Running the unit's at a diffrent freq. will be fine.

And that, my friends... is key.

If you're trying to run two sounders with two transducers at the same frequency... you will likely have interference.
If you run them at different frequencies, you should be OK.

As always... your circumstances might differ, but that is the basic premise when running a pair of transducers at the same time. :wink:
dcunniff":3be8b1n1 said:
Clockwise rotating props drive the recommendation on single screw setups to mount the transducer on the starboard side, to minimize bubbling affecting the transucer on the port side.Dana

In my planning, I forgot about that. I wonder if the prop effect would affect the speed paddlewheel?

I have the boat untarped and took photo of sounders.

Bubbles shouldn't affect the paddlewheel, they are well protected. Growth affects them more.

My oldest wheel is from '97 and still works. The other one is a year old, but I get speed signal from my GPS.

Photo shows first 120 KHz sounder on the right and the 50/200 kHz sounder added last year. Then have a hockey puck in the bilge for a digital depth display up to 200' at the instrument panel. Can see the start of the I/O housing at the left edge of the photo.



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Also, here is a photo of the third depth sounder in the bilge.

This is the hockey puck epoxied into the center flat of an I/O bilge, a duplicate 200 kHz only signal to a digital Uniden display (0-200' only) on the instrument panel. I have it on a switch to decide if I want it on with the transom mount fishfinder transducers.



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Took awhile to finish the description of having more than one depth sounder. Prior photos showed the transducers.

Here is a photo of the displays.

The top right one at the top of the right window is last year's digital Raymarine sounder. On the flat part of the helm the one closest on the left to the steering wheel is a Navman GPS chartplotter also from last year. Both are color and linked by NMEA.

To the left of the Navman is an old Apelco black and white depth sounder/plotter.

To the left of the steering wheel on the instrument panel at the top is the hour meter and then in part of the photo below it is the Uniden digital display of depth.


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