Transducer Mounting / Interference Question

I have a fiberglass boat with a shoot-thru-hull transducer for the graph on the console.

I want to add a graph by my kicker motor and am wondering where I can put the 2nd transducer to not get interference with the 1st transducer (they will be the same frequency). I could mount a 2nd shoot-thru-hull transducer about 2-3 feet away from the 1st one, would they interfer with each other? Or I could mount a transom transducer about 3 feet away from the shoot-thru-hull transducer, will they interfer with each other?

Someone told me that running 2 shoot thru hull transducers in a glass boat will always interfer with each other because fiberglass conducts the signal, doesn’t matter how far apart they are. Does anyone know if this is true?

Thanks for the help.

If they are the same freq. and you want to run them both at the same time ( do you need to run them both at the same time?) it’s not going to work on the back of the boat, My LX3 and my x51 would get a little interference between each other with one transducer on the back of the boat and one on the bow mount trolling, though I did get interference, it wasn’t enough to render either one useless. I really don’t think that will work if you want them both on the back. I’m not sure the glass boat is any part of the issue, for say, I think you’d have issues on any boat under these circumstances.

If you are running Lowrance units, you could get a switch that sends the signal from your in hull transducer to one of two displays, you would just have to flip a switch to divert signal to your console or to the graph in the back of the boat.

WalleyeDave, Will you have to run these two units at the same time. I wouldn’t think you’d have to run the console unit while you’re at the kicker, nor the kicker unit while you’re at the console. If that’s the case, just shut down the unit you’re not using and you won’t have to worry about interference. Otherwise, I would get a second unit that runs at an alternative frequency and mount it to the transom.

FYI, I just listed this little Raymarine unit in the classifieds here. I would think a unit like this would be a good option for a kicker unit. It offer 200/50 khz options.

Regarding interference in general, anytime you have two units running at the same or similar frequencies you’re going to be subject to some interference. The interference will occur when the two sonar “beams/cones” crossover one another. So, if you have a transducer on the transom and one at the bow, you won’t see interference unit about 25 feet of water (the depth at which the cones overlap). But, if you have two transducers (of similar frequency) closer together and running at the same time, you will get interference much sooner/shallower.

One method to reduce the risk of interference is to adjust the ping rate on one unit. The ping rate is the rate at which the unit send out a signal. The idea is to get one unit pinging while the other is not – to alternate the signal, so to speak. This may need to be done a number of times, as the units may “sync-up” again.

Another option is to run units at different frequencies. If you have one unit at 200khz, get a second unit that runs at 200/50khz and switch it to 50khz when you run both units at the same time. The downside to this option is that at 50khz the clarity and definition is not as good, so the effectiveness of the fishfinder is compromised a bit at 50khz.

To sum it up, in an effort to reduce sonar interference, a guy can:

1) Mount the two transducers as far apart as possible.

2) Run the two transducers at different frequencies (at least 50 khz separation)

3) Adjust the ping rate on one of the units to offset the sonar signals

Remember also that interference can be tolerable. It isn’t always that bad and may be something you can live with while enjoying your time on the water.

Thanks for the info, I was afraid I wouldn’t be able to avoid the interference issue with two transducers (same frequency) that close but thought I would check.

I want to put a 332c at the kicker and tie it to the Lowrance network so that rules out the Raymarine unit. If I get interference I’ll turn the console graph off – but I hate the idea of having electronics turned off

I have had this problem I have an x15 on dash and an x67c by the kicker. What works best is to turn the x15 to map and speed and watch my depth on x67. Sometimes when they were both on the graph they would work sometime they would be all messes up but if only the one was on graph they work fine together.