# Another transducer mounting question



## kanaka (Oct 3, 2007)

Upgrading system Humminbird 747C to a Helix 10 so new transducer going in.
Here's where it gets interesting with conflicting distances.

Humminbird says 15" or more from outside of prop. That's not from prop edge to hull, it's straight line out from hull then distance to prop the way I read it.








Airmar transducers says 3" from outside of prop using same logic.

What's up with the big differences? Is one company worried more about ventilation to the prop than the other?

Right now, transducer is mounted using HBs method and is next to a strake area. Never been happy with that location. Plus this transducer is huuuge compared to old one.


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## Sequoiha (Sep 28, 2007)

I would keep it as far from the prop as possible, not only will it cause noise but ventilation as well, at least a strake only causes noise, pick your location wisely.


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## RMS (Dec 9, 2008)

Generically, you want to stay just inside the most inside strake. I agree with Airmar, the proximity to the prop is secondary to staying away from the strakes.
Hard to argue with Airmar about transducer installation.

It would help a lot to see a picture of your hull, every hull is different.

Also, depending on the transom vertical angle, lack of transom setback, and lack of a jackplate as is more common on aluminum boats and skiffs it might be necessary to trim the motor up a bit to keep the lower unit from blocking the sidescan beam in the direction toward the lower unit.


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## X-Shark (Oct 3, 2007)

RMS has a LOT of good points, which proves that different hulls will be different ways.

There are stepped transom's....Like you see on Cape Horns. They cause some problems. People tend to install the X-Ducer in the wrong spot on those.

But follow Airmar. 

Installing to far out to the side can cause bubbles on the face due to rocking. I had to fix a thruhull one time due to that.


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## kanaka (Oct 3, 2007)

Here's pic. From left to right, 1st mark is the OD of prop. 2nd is 15" from 1st mark and where the old transducer was mounted. Where old transducer is dangling off cable is 10" from OD of prop and I'm leaning towards that area.
When I first got the fishfinder, I mounted the transducer alllll the way to the right corner, you can probably see the patches. That was stupid.

Click on pic to enlarge


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## X-Shark (Oct 3, 2007)

Yea.....Where it was before is right on the Strake......That's a No-No.

From the inboard mark going Outboard....... Mount it just to the Outboard side of That next Scupper hole.


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## Boat-Dude (Sep 24, 2011)

Bobby what do you think about these transducer pads.

*Stern Pad - Standard Size - White*


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## kanaka (Oct 3, 2007)

Didn't get to see X-Sharks post till now. 

Ended up mounting it where the old one was dangling. Wanted to get screws back in the holes before the rain. It's 5" away from that strake, guess if it's still too close, patch and drill new holes. 

And a big thank you to everyone for all the input. :thumbsup:


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## RMS (Dec 9, 2008)

It should be fine where you mounted it.

Of course you still need to get the height and fore/aft angle dialed in.


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## kanaka (Oct 3, 2007)

Great! Easier to adjust angle because they're using a star washer instead of preset notches.


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## X-Shark (Oct 3, 2007)

Boat-Dude said:


> Bobby what do you think about these transducer pads.
> 
> *Stern Pad - Standard Size - White*



Don't know anything about that.....I have made some to cover the holes and mount the 3rd X-ducer on a boat.


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