Topic: Using 2 transducers with 3 head units

[EZM]

Hi,

I did not want to hijack another thread and could not find exactly the info I was looking for .......

I am running one 898c HD SI unit and one 858c unit at the helm.

I am also putting another 858c unit at the bow.

All will be on a 5 port Ethernet.

The boat is a 2013 1800 Lund Tyee (Aluminum) so a thru hull transducer is not an option (I think).

Here is my question / concern - I keep hearing the SI transducer does not work well at high speeds and may lose basic 2D sonar function. This is scary to me. I need to ensure I understand and see my depth at cruising speed.

So, adding a second transducer is the obvious answer (I think).

I understand (think) you can't run one transducer to the 858 and the other transducer to 898 because of interference so one needs to be switched off while the other is active (I think). If there was no interference - then I'd just run one transducer to each unit and be done with it. The bow mount, of course, would need to share the transducer of it's sister unit at the helm (858's).

The SI transducer from the 898, I assume, for best performance, will be mounted according to plan (15" away and to the right of the centerline of the hull according to standard mounting instructions).

The standard (high speed use) transducer (not sure what exactly it is) from the 858 will be mounted as well but lower and closer to the center line of the boat.

so here's the question .....

What do I need to make this work (parts)?

Should the SI be higher up the transom and if so, won't the high speed transducer off the 858 be "in the way" and casting a shadow?

Should I maybe mount them on opposite sides or does it matter?

xxxxx

My screen set up at the helm will look like this (primarily)....

898 at helm, will display DI and SI on a 50/50 split screen
858 at helm, will display 2D sonar and Chart on a 50/50 split screen

The bow mount unit will only be used at low speeds or at anchor - 2D sonar and Chart.

[Humminbird_Greg]

EZM,
You have several different questions here, so it is a good thing that I eat lunch quickly!

The high-speed depth readings:

RadarSonics makes the AlumaDucer which is designed to work as an inside-the-hull transducer on aluminum boats.  However you still have to be able to mount it in a location that does not have aerated water flowing across the hull.  I have never mounted one but have heard good and bad results from those who have.

The HDSi transducer can work at high-speeds as long as you can get it mounted in a location that will allow it to do so.  That means it has to be mounted in an area that has air bubble free water flowing off the hull.  This is not something that a lot of aluminum boats have so it will be a challenge regardless of type of transducer it is.  The fact that it is a physically larger transducer and the fact that you also have to mount it in a location that will allow the Si sonar to work just makes it harder to find this mounting location.

You may be able to run more than one sonar unit on a separate transducer at a time without interference but luck would have to be on your side to do so.  The water depth, bottom composition and some other things can make this more or less likely to make it happen.  If it does happen many are able to turn up the Noise Filter menus on their units to filter the interference out, some cannot and so must turn off the sonar on one unit to get rid of it (this is why the Sonar menu is now also on the power button).  Your choice as to whether you want to run one, two or three sonar units at the same time or not.  You have some options though as all three 800 series units are Ethernet capable and you could share some of the sonar between units.

That 15 inch rule is normally for inboard props and not outboard motor boats (unless you also back troll).  If you plan on mounting more than one transducer on your boat’s transom try and keep the HDSi transducer as far away from the second transducer as you can so that the second transducer will block less of the Si sonar to that side.

What parts you need will be dictated in how you want to try and make this all work.  You have options here that have not been stated like being able to Ethernet connect the units or maybe just two of them.

Will you use just the HDSi transducer with your 898 unit or will you try a second transducer with it as well (like the XNT-9-20-T transducer that comes with the 858c units or maybe the XSO-9-20-T Stick-On transducer?) and if so how will you connect them: AS-Si-DB-Y splitter cable or TS3 Transducer Switch?

Personally I would try and go with just the HDSi transducer off the transom unless you fish in areas where it could get damaged.  Then I would go with the second Dual Beam transducer (XNT-9-20-T or XSO-9-20-T) to help keep the HDSi transducer from being damaged.  Of course this really depends on how much clearance you have between your transom and the foot of the motor – don’t want that blocking any Si sonar.


Okay, it’s a little past lunch now so back to those month-end reports!
Maybe after answering just one more question… 

[EZM]

Thanks for info Greg ...

Really - the key thing is for me to have reliable high speed sonar while cruising AND SI/DI when I'm low speed trolling or still fishing.

I like the idea of having my two 858's use the their own transducer and have the one 898 use it's own transducer. If I could do this without interference - we would be in business.

I am also OK having both transducers in place and switching them as conditions dictate - if this requires me to go into the settings of all three head units each time that would be a painful process everytime I pick up and change fishing spots all day long.

Some sort of toggle switch on the dash is my vision of a "perfect" fix. Or the use of a cable that makes this happen would be cool too - I guess i have no idea really how to make this happen ......... hence my questions.

There should be about 6"-8" of clear space between the leg at it's downmost position and the hull. I could very easily trim it up and gain a few inches without any problem for low speed trolling.

The low speed or resting "water level" on this boat would be just below (a few inches) where the black part of the boat meets the grey/silver part. Up on plane, of course, it would be a few inches lower.

I enclosed a picture of the back of the boat and put a yellow square where I "think" would mount the SI transducer. It would sit higher up on the hull (maybe 1/2" higher than the bottom of the hull) and up and away from the trailer bunks. Loading and Launching is the only time I'd likely be knocking the transducer. This would be approximately 15-18" from the centerline of the hull.

The red square is where the transducer would go, conventionally mounted, slightly proud of the hull, but far enough toward the centerline, away from the double bunks, to avoid bumping it during loading and unloading of the boat.

How do i make this happen to avoid the least amount of "fuss" when switching back and forth between transducers? (I am still assuming I can't run them both at the same time).

As a side note - I Don't necessarily need a reading off the SI unless I'm trolling or still fishing at all.

My screen set up, during still fishing/trolling would have been;

858 50/50 split screen chart/2d sonar (both units)
898 50/50 split screen SI/DI

How do I make this happen - and what do I need to install and buy?

[Humminbird_Greg]

I would go with the 898 unit being connected to both the HDSi transducer and the 2D XNT-9-20-T transducer via the AS-Si-DB-Y cable.

The console mounted 858 unit gets Ethernet connected to the 898 via an AS-EC-XXE cable.  You will be able to share the 2D sonar from the 898 to the 858 unit without any chance of sonar cross-talk interference.
[For the AS-EC-XXE cable, replace the “XX” with the cable length you need.  These some in 2, 10, 15, 20 and 30 foot lengths: http://store.humminbird.com/category/629916/Ethernet]

The bow mounted 858 gets its own XTM-9-20-T transducer.  Call Humminbird about exchanging the stock XNT-9-20-T transducer out for a trolling motor mount XTM-9-20-T transducer.


If you want to Ethernet connect all three units together you will need the AS-ETH-5PS Ethernet Switch plus the needed AS-EC-XXE cables,


I would mount the transducer in the locations you indicated though I think that XNT-9-20-T transducer would need to go closer to the centerline.  I understand that you cannot due to the location of the bunks.

[EZM]

Awesome - I think I got it ......

So if I use the Y cable - which splits the frequencies and transducer signals - this will eliminate all interference? That is great.

so ..........The Y cable will plug to the back of the 898 and then the Y cable to each of the 2 transducers (one SI transducer and the other 858 stock transducer).

I am running a 5 port hub anyways so that takes care of the units sharing data. The 858's will simply be set up to use the 898's split signal (but, of course, be only able to get 2d sonar as they only have that capability). The 898 will get the SI/DI sonar data from the SI/DI transducer AND the 2D when at high speed.

Essentially both transducers are working all the time but not shooting the same frequency so there is no interference?

I could very easily move the stock 858 transducer very close to the center-line - there is no bunk in the middle and the motor leg is far enough away.

The only issue then, might be that we have not addressed, is the standard transducer "casting a shadow" and getting in the way of the SI signal. It is obviously lower on the transom and now, and would be closer as well.

Is that not a big concern? - I was trying to get them as far away from each other because of the shadow it might cast? It doesn't sound like that's a big deal maybe?

Thanks again Greg .......

[Humminbird_Greg]

“So if I use the Y cable - which splits the frequencies and transducer signals - this will eliminate all interference? That is great.”
It will stop any interference between the 898 unit and the console 858 unit but only because you are going to share the 2D sonar data from the 898 unit with this 858 unit.  That means only one of these units will be transmitting and receiving at a time.

"so ..........The Y cable will plug to the back of the 898 and then the Y cable to each of the 2 transducers (one SI transducer and the other 858 stock transducer).”
Yes.

"I am running a 5 port hub anyways so that takes care of the units sharing data. The 858's will simply be set up to use the 898's split signal (but, of course, be only able to get 2d sonar as they only have that capability). The 898 will get the SI/DI sonar data from the SI/DI transducer AND the 2D when at high speed."
The 898 will get the Si/Di sonar data and water temperature from the HDSi transducer and always get the 2D sonar from the stock 858 2D transducer (XNT-9-20-T).

“Essentially both transducers are working all the time but not shooting the same frequency so there is no interference?”
Yes.

“The only issue then, might be that we have not addressed, is the standard transducer "casting a shadow" and getting in the way of the SI signal. It is obviously lower on the transom and now, and would be closer as well.

Is that not a big concern? - I was trying to get them as far away from each other because of the shadow it might cast?  It doesn't sound like that's a big deal maybe? ”
It is a concern.  The closer the two transducers are the more of the left Si sonar signal the 2D transducer will block.  You could try mounting the HDSi transducer farther out to the outside of the boat but that may also put it up higher and the motor mount may start blocking some of the upper part of the left Si sonar.