Side Imaging Transducer Options. Thru-Hull or Transom Mount?

sutor623

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Hey guys I am soon to be purchasing a Humminbird 998c si. I was looking at the transom and the skeg is going to be in the way of the ducer if I mount it on the transom. These SI ducers need a full 180 degrees of clearance or you will have an obstruction in your view. Have any of you guys mounted the plastic thru hull si ducer in the keel of the back end of any aluminum boats? The dead rise is high enough that if I mount it directly in the center my si ducer will have plenty of clearance. I posted a pic of my Starcraft, do you guys think it will be a good idea to trade my transom mount for the thru hull? It would be a crime to drill through my precious aluminum if it is going to be less than ideal. I'd like to avoid mounting two transducers because it is expensive and doesn't look good in my opinion. Plus it just something else to have to keep watch for. P.S. I am now on a different trailer, and there are no keel rollers.
P4291144.jpg
 

sutor623

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Re: Side Imaging Transducer Options. Thru-Hull or Transom Mount?

Guys any input?
 

bassman284

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Re: Side Imaging Transducer Options. Thru-Hull or Transom Mount?

Waiting for someone more expert than me, but I don't believe a side imaging transducer will work thru hull.
 

sutor623

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Re: Side Imaging Transducer Options. Thru-Hull or Transom Mount?

Bassman humminbird actually has a si that will work but it is not pass thru hull, it is drill thru hull.
 

beardeddone

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Re: Side Imaging Transducer Options. Thru-Hull or Transom Mount?

Guys any input?

Judging where you have the one shown in the pic if you were to put the new one there you should be good to go, that is where most all are mounted and they all seem to work pretty good there in that location, jm.02w
 

UncleWillie

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Re: Side Imaging Transducer Options. Thru-Hull or Transom Mount?

The rules for mounting a side scan transducer are different from Down Imaging/Fish Finders.
Be sure anyone recommending the location has actual experience with side scan transducers.
This is from experience.
I have a 798ci si.

Where it is in the picture will be a problem.
The output of the transducer (Red Line) will be in the turbulent, bubble filled water behind the transom to the port side.
This will give a huge amount of interference in the left side-image.

SideScan1.jpg

Mount it to the right of dead center much lower. (Red Arrow)
As long as the seam half way up the transducer is at, or nearly at, the same level as the keel, it will see to port with a good image. (Green Line)

If you attempt to keep it just to the right of the Anti-Ventilation plate when pointed straight ahead, any issues with disturbing the water flow to the prop at full speed will be eliminated.

Location #1 was bad idea #2 was a winner.
SS1.jpg
 

sutor623

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Re: Side Imaging Transducer Options. Thru-Hull or Transom Mount?

Thanks Willie great reply. Actually the transducer in the pic is a traditional sonar ducer on my basic fishfinder. That will be coming off. The location that you are suggesting will solve the left-right dilemma as far as not having the hull block the si, but unfortunately even in the location that you are suggesting the L/U skeg will be in the way of the portside si. As you can see in the photo, I think my only option is to
get a power tilt and trim, or get out my drill and mount thru the hull.
P3191010.jpg
 

UncleWillie

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Re: Side Imaging Transducer Options. Thru-Hull or Transom Mount?

Yep, that motor is sure tight to the hull trimmed in.
I can't see why you would operate it that far in though.

Side scan is not of much use at high speed.
It is used mostly at trolling speeds.
The DownImaging/DepthFinder works fine at high speeds.

If you trim out you may get enough space to peek in front of it.
You will only need 4-1/2 inches. (I just measured it!)

Trimming out at trolling speed should not be an operational issue.

Installing the Thru Hull SI Transducer requires cutting the spacer in half at your dead-rise angle.
The transducer needs to be straight down.
 

sutor623

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Re: Side Imaging Transducer Options. Thru-Hull or Transom Mount?

4.5 inches from the back of the ducer, of 4.5 inch clearance for the ducer? I was considering mounting the thru hull smack in the middle of the keel.
 

UncleWillie

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Re: Side Imaging Transducer Options. Thru-Hull or Transom Mount?

The SI transducer projects just a hair LESS than 4.5 inches out from the transom.
If the front of your engines drive housing is more than that from the transom, you should be good to go.

Remember the beam is 86 x 2 (172 degrees) Covering Left, Down, and Right.
It is much less than three inches wide front to back.

As long as you can see 5 inches if light between the Transom and the Motor, The SI will be able to see through there also.
It is extremely narrow as it comes out of the transducer.
Kind of like the sound version of a Laser Beam.

SideScan2.jpg

It is night and snowy here so this is the best I could do on short notice.
 

sutor623

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Re: Side Imaging Transducer Options. Thru-Hull or Transom Mount?

Thanks Willie! I appreciate you spending the time with my photos and taking some of your own. Lets hope others see this thread down the road an get some good info from it!
 
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