Humminbird 998c SI 2 transducer installation?

[mnhunter2]

I am installing a 998c si and was told that I would get better performance if I used a high speed transducer for a high speed reading and then use the standard transducer for the SI. I was wondering if anyone else has done this and how they located the transducers, any comments would be helpfull!!!!

[PerchJerker]

Yes, I've done it. HB gives you the option of buying and using the Y cable and the 2nd transducer. With Lowrance the standard setup is 2 transducers. We've seen and done a lot of them both ways.

You still mount the skimmer transducer for the conventional sonar the same as before - so it's flush with or barely below the bottom of the hull, and in "clean" water (no cavitation from rivets, strakes, props, etc.).

The SI transducer is typically mounted higher than the bottom of the hull, to help protect it (they're expensive) and to reduce spray issues. Put it low enough so it's in the water at 10 mph and less, put it high enough so it's out of the water when you're running on plane. SI images are best at 8 mph or below, so there's no reason to have the transducer in the water when you're going faster than that.

And with the SI transducer, make sure it has good views to the left and right, not blocked by anything in the way.

[Carpenter]

how does a HB system know when to use which transducer when using the y cable? or does it always pull the solar from the std ducer and the SI from the SI?

[PerchJerker]

how does a HB system know when to use which transducer when using the y cable?

If I remember correctly, the HB always uses the SI transducer unless it has lost its reading on the bottom, and then the HB automatically switches over to the conventional skimmer transducer. It must check back with the SI transducer, because when you come off plane it reads the SI transducer again. That logic allows you to put the SI transducer higher on the boat, so it is out of the water and protected when you're running on plane, which also relieves the sprayback issues.