what do I need to know running 2 fish finders?

[hankll]

I have a Bottom Line Tournament 3310 SideFinder/ fish finder with transom mount transducer. This unit has temp and speed sensor also. I have a Garman fish finder that I'd like to mount transducer on my TM, with screen up in bow so I can see fish without having to turn around to look at the other unit. \\

Question I have is, Can I run both at the same time or is there a signal overlap problem.

 

[tashasdaddy]

Re: what do I need to know running 2 fish finders?

set up correctly you can run both.

 

[hankll]

Re: what do I need to know running 2 fish finders?

Tashadaddy - Can you define set up properly, I mean is there something I would see in the returns on the screen, maybe?

 

[John_S]

Re: what do I need to know running 2 fish finders?

I think it mainly depends on the transmit/receive frequencies. If they are both the same frequency, you will start to have interferance as you move into deeper water. How deep depends on cone angle and how far apart. You can adjust the trolling motor one to shoot slightly forward and transom to shoot slightly aft. That will help you go a little deeper before you get interferance.

The Garmin is probably a single beam 200kHz transducer. I don't know what Bottomline used for side finder. Humminbird used 455kHz for wide side finding, but 200kHz for the bottom facing beam.

 

[fuzzeywiggler]

Re: what do I need to know running 2 fish finders?

If you wanted more seperation with the two finders and if you have a trolling motor you could always mount one transducer one it. I have seen it done before.

 

[hankll]

Re: what do I need to know running 2 fish finders?

Ok, that being said...the Bottom Line unit has a bottom frequency of 200KHz and 18 degree cone while the Garman 100 unit also has 200 KHz with a 20 degree cone. So from what you indicate these two units would interfere with each other, so I would have to shut off one to use the other? The side finder frequency is 455KHz w/ a 9 degree cone so I would assume I could only use the side finder freq setting on it and bottom cone on the Garman? Maybe?

 

[hankll]

Re: what do I need to know running 2 fish finders?

I see now what you mean, the deeper the search the wider the cone which would overlap each other at some point depending on depth of the cone overlap.. Hmmm, wonder how to calculate the depth at which they would overlap.

 

[hankll]

Re: what do I need to know running 2 fish finders?

And when we are saying interference, what exactly happens? no return, or false returns to both units?

 

[hankll]

Re: what do I need to know running 2 fish finders?

According to Bottom Line manual, to calculate the diameter of the cone divide the depth by 3 so since my boat is 20 ft, that would mean aprox 60 foot depth would give me a 20 foot diameter of cone or 10 foot radius or half my boat length which would be theoretically the depth of no or little interference between the 2 units.....I guess I answered my own question, except what happens if there is interference?

 

[Silvertip]

Re: what do I need to know running 2 fish finders?

I wouldn't worry too much about interference unless you get into "really deep" water. Two boats ago I had two Eagles with one transducer at the stern and the other on the troller. They did not interfere with each other. But to me, anything over 90 feet is deep. I'm a fresh water guy. My last boat had an Eagle and a PinPoint and they didn't interfere either. My new boat will be equipped the same way.

 

[hankll]

Re: what do I need to know running 2 fish finders?

Strictly fresh water and water I fish in usually not much over 90 ft in the channel of the lake, not likely to be fishing just looking while underway so bow fishfinder wouldn't be in play,anyway.

 

[Boatist]

Re: what do I need to know running 2 fish finders?

I seen several bass boat set up this way and on a 19 foot good to about 30 feet. Think about it, with a 20 degree transducer the circle under the boat, the transducer covers is about 1/3 the depth. So in 30 feet of water the transducer cover a 10 foot circle. When the signal hits the bottom it bounces back up but the sound signal will continue to spread.

If you turn the sensitivy up like you should when trying to see fish then a 20 degree transducer will actually see and larger area. If you set it low to just see Bottom depth then can go a little deeper. Another factor is the power of the transducer. 500 watt transducer will make the other unit more likely to see the other unit.

What happends when deep enough to interfere. Each unit will see the return of the other unit but since it is the same frequency it will think it is it own return. Since the units are not timed together it could display the other unit return like it was one foot or 60 foot. Both units will get confused and most of the time will have a flashing depth meaning it not shur where the bottom is. Best to go with different frequencys or just turn the back unit off when the trolling unit is in use.

 

[cbavier]

Re: what do I need to know running 2 fish finders?

I run two Fishfinders at the same time without any interference . I might be able to help you. I run a Hummingbird from the dash and an Eagle from the transom.
Both have 20 Dg cones. I put the Hummingbird on the dash because I like you didn't want to be turning around all the time and furthermore I couldn't hear the Depth Alarm on the Eagle with the Engine running. 4.3 Mercruiser 185 HP so the dash Mount unit was necessary if nothing more than for the depth Alarm.

First Keep the wiring on separate sides. One down one side and the other on the other side. The signal will jump from wire to wire or Cable to cable. Why ????

Second mount the Transducers on opposite sides of the Transom. In 100 Ft of water I get no interference.

You should have no problem either.

Like Boatlist said if you go to Manual. Then turn one unit off or you may encounter some interference if your sensitivity is set too high. I find mine work good in unison if I just leave them in Automatic.

 

[John_S]

Re: what do I need to know running 2 fish finders?

HankII,

I wouldn't worry about calculating at what depth you might see interference. Go ahead and run them and see where it is. If it is a problem, then its not hard to shut the helm off as you move to the bow.

I only run mine in auto, when not looking for fish. ie just when I care what the bottom depth is. When fishing, sensitivity is usually at max or very close and top part of the water column is filled with clutter.

My interference is similiar to Boatist, but I was also using the same type sonar for both (3 beam Humminbird Portrait/400tx). Mixing brands types, I wouldn't want to guess. If you see something happening, turn one unit off and see if it goes away.

 

[MrBigStuff]

Re: what do I need to know running 2 fish finders?

When I bought my 17' bass boat, it had two independant fish finders on it by different mfrs. One was mounted to the bottom of the TM, the other at the transom. They ran on different frequencies and had fairly tight cone angles (20deg IIRC). I had all kinds of interference issues at any depth over 10'. The result of interference was a bunch of false signals that made both displays unusable. After a few months of jockeying between the units depending on if I was motoring or trolling, I finally just took one of them completely out and used two transducers with a switch. Mounted the display on a swivel so I could see it from any seat.

Since a number of people had no problems, I suspect that much depends on the quality of the units and how well they discriminate. So, you'll only know by trying. Just don't permanently mount anything until you run a water test.

 

[cbavier]

Re: what do I need to know running 2 fish finders?

When I bought my 17' bass boat, it had two independant fish finders on it by different mfrs. One was mounted to the bottom of the TM, the other at the transom. They ran on different frequencies and had fairly tight cone angles (20deg IIRC). I had all kinds of interference issues at any depth over 10'. The result of interference was a bunch of false signals that made both displays unusable. After a few months of jockeying between the units depending on if I was motoring or trolling, I finally just took one of them completely out and used two transducers with a switch. Mounted the display on a swivel so I could see it from any seat.

Since a number of people had no problems, I suspect that much depends on the quality of the units and how well they discriminate. So, you'll only know by trying. Just don't permanently mount anything until you run a water test.

I suspect the two Transducers were too close together or the Cables were run side by side. THE CABLES MUST BE SEPARATED AS WELL AS THE TRANSDUCERS according to Factory Techs from both Hummingbird and Eagle. I suppose both Heads would have to be separated also but that wasn't an issue with me as one Head is on my Dash and the other Head is on my Transom which is what I wanted. I know because I called both Eagle and Hummingbird and talked to Techs. Hummingbird is now owned by someone else so I had a bit of a time to get to the right place for support. By the way the Eagle is far superior. I don't think I would purchase another Hummingbird product. I'm not happy with mine and have talked to several other people who have expressed their dissatisfaction with theirs too.

 

[hankll]

Re: what do I need to know running 2 fish finders?

Ok, thanks for all the feedback .... since my Helm has side finder at 455 KHz and transducer mounted on transom, I should be able to use it at same time as my Humminbird since it will be mounted in bow and transducer on the Troller, I shouldn't see any interference with the sidefinder use while reading bottom with the bow unit. In any case my usual fishing depth isn't going to be all that deep maybe at most 25 feet, so I'll try both bottom signals together, unless with the above mentioned possible problems of interference, then I'll just run the bow unit when I'm up there fishing and the helm when I'm running down lake looking for more fish returns. But at least I know what to possibly expect, either way.

 

[MrBigStuff]

Re: what do I need to know running 2 fish finders?

I suspect the two Transducers were too close together or the Cables were run side by side. THE CABLES MUST BE SEPARATED AS WELL AS THE TRANSDUCERS according to Factory Techs from both Hummingbird and Eagle. I suppose both Heads would have to be separated also but that wasn't an issue with me as one Head is on my Dash and the other Head is on my Transom which is what I wanted. I know because I called both Eagle and Hummingbird and talked to Techs. Hummingbird is now owned by someone else so I had a bit of a time to get to the right place for support. By the way the Eagle is far superior. I don't think I would purchase another Hummingbird product. I'm not happy with mine and have talked to several other people who have expressed their dissatisfaction with theirs too.

Your suspicions were incorrect. Perhaps it wasn't clear in my first post. One unit was located on the trolling motor at the front of the boat, the other at the stern. Both were fully independant and the heads were at either end of the boat. They were even powered off of two different, isolated batteries. I calculated the cone angles and the depth at which they would overlap. The interference occured at a much shallower depth than the math would lead you to believe.

The wife now gets exclusive use of the "fish TV" while we fish. So naturally I resorted to the position that, being a male, I don't need directions or a stinkin' locator to catch fish The best part is when the wife says, "there's a fish under the boat" and hauls it up shortly afterward. ;-P

 

[cbavier]

Re: what do I need to know running 2 fish finders?

Your suspicions were incorrect. Perhaps it wasn't clear in my first post. One unit was located on the trolling motor at the front of the boat, the other at the stern. Both were fully independant and the heads were at either end of the boat. They were even powered off of two different, isolated batteries. I calculated the cone angles and the depth at which they would overlap. The interference occured at a much shallower depth than the math would lead you to believe.

The wife now gets exclusive use of the "fish TV" while we fish. So naturally I resorted to the position that, being a male, I don't need directions or a stinkin' locator to catch fish The best part is when the wife says, "there's a fish under the boat" and hauls it up shortly afterward. ;-P

MrBigStuff: Do you like the Fish TV? Which model do you have?

 

[Silvertip]

Re: what do I need to know running 2 fish finders?

I've run many combinations of locators, including two Eagles (bow and stern mount) and the only interference I've encountered is on the radio. Granted, I'm generally in less than 90 feet of water and average 40 feet or less so depth is definitely an issue. All of the bow mounts have used trolling motor transducer mounts. My new pontoon combination is a PinPoint and a Lowrance but it hasn't been tested yet as I'm not finished rigging. If it doesn't quit raining soon I may be able to test it in my driveway.