tranducer interference?

[grizzly1654]

I recently installed 2 Helix 7 si gps G2N units on my boat. 1 at the console and 1 at the bow. My bow unit is working fine, the transducer for it is on the trolling motor.

 

The unit at the console appears to be getting a bad reading. The transducer for it is mounted on the transom.

 

Sorry for the sideways pics. I couldn't figure that one out.

 

It is getting that fuzzy line on what is supposed to be the left side (bottom in this pic), right beside the boat. The only time this line will go away is if I get above 4mph.

Ive tried with the motor running and shut off. Trimmed all the way out of the water or trimmed all the way down. This is a bad pic but the left side outer range of the si is alot darker also.

I didnt have a blank card with me so this crappy cell pic is all i have for now.

 

Here is how my transducer is mounted currently. This is the position that gave me the best results. Ive tried adjusting it as far as the slots in the mount will let me in either direction.

Anyone have any ideas?

[WIGuide]

It's hard to tell from the pictures you posted but, it looks like you may have mounted the transducer right behind a strake. This will cause turbulence and make for poor readings. 

[J Francho]

It needs to be mounted so it site level, below the hull.

[Wayne P.]

Your SI pulses are recording disturbed/aerated water coming off the hull. That is normal.

Since the keel is deeper than the hull to the starboard side of the transducer, you get more disturbed water recorded on the port side.

 

Same thing in this screen shot:

[Wayne P.]

This screen shot is with a SI transducer a little higher above the hull bottom for stump clearance and it has disturbed water echoes on both sides, but still the keel side has more.

 

[12poundbass]

11 minutes ago, Wayne P. said:

This screen shot is with a SI transducer a little higher above the hull bottom for stump clearance and it has disturbed water echoes on both sides, but still the keel side has more.

 

How do you resolve this or is it just a matter of limiting the amount you have?

[Wayne P.]

You have a Side Imaging unit, it sees stuff to the sides and aerated water is "stuff" that reflects sonar pulses.

 

The only way to prevent it is have the transducer over a foot below the hull bottom so it may not see it. Humminbird Side Imaging covers from the water's surface to past vertical under the transducer on both sides.

[grizzly1654]

2 hours ago, WIGuide said:

It's hard to tell from the pictures you posted but, it looks like you may have mounted the transducer right behind a strake. This will cause turbulence and make for poor readings. 

It is mounted directly centered between 2 strakes in the flat area. It is hard to see in the picture.

 

1 hour ago, J Francho said:

It needs to be mounted so it site level, below the hull.

The first time out I started with it level. Like it is now was the position that gave the least fuzzy line.

 

31 minutes ago, Wayne P. said:

Your SI pulses are recording disturbed/aerated water coming off the hull. That is normal.

Since the keel is deeper than the hull to the starboard side of the transducer, you get more disturbed water recorded on the port side.

 

Same thing in this screen shot:

Ok thats good I was worried I was going to have to drill more holes in my boat lol.

I was thinking with the line on the left side that I would be getting bad readings.

 

Thanks for the help guys.

[12poundbass]

Makes sense. The reason I asked was I've seen screen shots of some that shows a lot of disturbance and some with little to none.