I am going to purchase a Hummingbird Helix si di chirp soon. What I want to do is install a transducer on the transom for Lake Superior and another on the trolling motor for inland. Is this setup possible? Is there a switch that can be used? If the trolling transducer is out of the water will it fry? I haven’t had a finder in 30 years. I’m a little confusicated.

To my knowledge, the transducer on the TM will not fry when out of the water. It might confuse the heck out of the graph.
 

I will submit this tidbit for your consideration, subject to over rule by those more knowledgeable here. I bought a Lowrance Hook2 Reveal 7 Tripleshot for the front of my boat. The sonar and DI are fine. The SI, I’m not so sure about. I’ve subsequently read that to get quality SI, your boat must be traveling 3-5 mph (if not more). My TM speed tops out about 2 mph. I think what I bought would be perfect for the console graph. Maybe not so much for the bow.  YMMV. 
 

As I said, I would defer to those with more experience with electronics. 

Yes, the set up is possible and no, you won't fry the transducer. 

the transdeucer will not fry. i use my unit to look at mapping mess with weigh points etc while the boat is in the garage. it wont hurt it. yes the boat needs to be moving about 3mph or so for the si to be most accurate. 

I never turn my bow hummingbird off when on the water. It will not hurt the transducer to be out of the water while the unit is on. 

In regards to boat speed in previous replies you do have to be moving but, it depends on your boat and how much turbulence runs across the transducer.

Generally I set the chart speed one notch higher than my boat speed. My setup paints a good side image picture from 2 to 5 mph. Faster than that and the picture starts to breakup. Slower the picture gets stretched and skewed. 4mph is where I generally run when scoping an area.

 

Thanks guys. I’m probably going to get the finder within the next couple of weeks. Should I order a Y cable to complete the install? As for the rear down imaging x ducer, will I have to change any settings as for the frequency between the two or will the graph know what’s up? 

I have a Solix not a Helix so I may not know what I'm talking about.  I don't think you can connect two transducers to one unit at the same time.  There is no switch that will work with high end transducers used by a Helix.  There are Y cables that spit the side imaging out to one transducer and DI and Sonar to another but not to run two transducer that do everything at the same time.   You can always disconnect one transducer and plug in another when you want to switch but that's a pain.  Like I said I could be wrong but I would check with Humminbird support before spending the money. 

 

Ok I’ll chime in too with, “ not 100% sure” but....

I have 4 Humminbird graphs. 2 at the bow and two at the console. They are all Ethernet connected.

If you go into MENU/MENU. Select ADVANCED SETTINGS.
You can then assign the transducer you want that graph to use. I believe it’s the last tab. You would just have to keep doing that from driving to fishing. Not that big of a deal. 
 

here is the manual

https://879dd651a809fc1b59de-035169dcc8fb0db4e46082ec8002cac8.ssl.cf2.rackcdn.com/HumminbirdManuals/532509-5EN_A - HELIX G2-G3-G4 Manual.pdf

On 5/10/2021 at 4:36 PM, Tennessee Boy said:

I have a Solix not a Helix so I may not know what I'm talking about.  I don't think you can connect two transducers to one unit at the same time.  There is no switch that will work with high end transducers used by a Helix.  There are Y cables that spit the side imaging out to one transducer and DI and Sonar to another but not to run two transducer that do everything at the same time.   You can always disconnect one transducer and plug in another when you want to switch but that's a pain.  Like I said I could be wrong but I would check with Humminbird support before spending the money. 

 

There are walleye guys running 2 SI transducers at once connected with a Y cable. When a SI transducer is mounted to the transom of an aluminum boat they are mounted on either side of the motor as opposed to the step like you would find on a bass boat. When the transducer is mounted to the step, you get an unobstructed view from both the left and right. When the transducer is mounted to either side of the motor on an aluminum boat, the lower unit blocks the returns on one side unless you're trimmed up high enough. 

6 minutes ago, slonezp said:

There are walleye guys running 2 SI transducers at once connected with a Y cable. When a SI transducer is mounted to the transom of an aluminum boat they are mounted on either side of the motor as opposed to the step like you would find on a bass boat. When the transducer is mounted to the step, you get an unobstructed view from both the left and right. When the transducer is mounted to either side of the motor on an aluminum boat, the lower unit blocks the returns on one side unless you're trimmed up high enough. 

Yes,  I aware of the Y cables that split out right and left sides of SI.  Also they have a Y cable that  separates down imaging and 2D from SI.   As I understand the OP's question,  he wants a transducer on the transom and one on the TM both connected to the same unit at the same time or a switch to select one or the other.  I don't think that's possible.

32 minutes ago, Tennessee Boy said:

Yes,  I aware of the Y cables that split out right and left sides of SI.  Also they have a Y cable that  separates down imaging and 2D from SI.   As I understand the OP's question,  he wants a transducer on the transom and one on the TM both connected to the same unit at the same time or a switch to select one or the other.  I don't think that's possible.

Gotcha

 

OP, Humminbird has/had a switch for switching between 2d transducers. Not sure if they have one for imaging transducers.