Two echo sounders on one boat!

R

Rigger

Well-Known Member
Joined
17 Jan 2004
Messages
354
Location
N Wales
Visit site
I've just bought a Garmin 550s chartplotter which includes an echo sounder display and transponder. I also have a (somewhat dodgy) ST 50 echo sounder fitted. Does anyone know if these can be used together at the same time or will the signals from one interfere with the other. Do the transponders have to be mounted a certain distance apart??
 
The garmin and the autohelm units both have 200khz transducers, so they will interfere. However, if you run the garmin at its other 50khz frequency then interference should not be a problem.
 
Well, if you already possess two echosounders, all you need to do is set up the second one temporarily (various ways of doing this, such as creating a small puddle to put the transducer in, also finds the best spot for it) and see if they both work.
FWIW I once bought a Garmin GPS which included a "fish-finder" display, which I set up mainly out of curiosity ... it worked very well and didn't interfere with the other (NASA) sounder.
 
Well, I've got three on my fishing boat, they all work at 200 and 50khz and they don't interfere with each other on any of the frequencies. Two are Humminbird and one is a Navman.

According to those that I've spoken to, it is more to do with where the transducers are sited rather than their frequencies.

So don't believe all you hear. Suggest you just try it.
 
Siting has little to do with things, geometric beam spreading on a 15 degree transducer will present a return greater than the size of an average bot in more than 15 metres of water. In practice it has to do with pulse timing and frequency drift.

A stated 200khz system can be as much as +/- 2khz off frequency,so it would be feasible to have two systems 4 khz apart from each other which in depth receiver terms is massive as they tend to have a very tight centre frequency with a huge roll off either side of the "tuned" frequency.

Beam spreading is one of the main reasons why a high frequency transducer does not work well in deep water as the returned signal is so small, the receiver has to be extremely sensitive to "see" the signal which then leaves it open to noise. Intensity decreases by the square of the distance.

Sound in water is a complex area and I am sure someone else will come along and comment on the above. I have an interesting presentation from my simrad days on "basic" hydroacoustics which is very heavy on the math that I could park somewhere if anyone was interested pm me.
 
You must log in or register to reply here.

Share this page

Top