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Author Topic:   Help! Installing a Transducer
KevinW posted 05-15-2002 10:43 AM ET (US)   Profile for KevinW   Send Email to KevinW  
Has anyone had the experience of installing a transducer on a 13'? I have a 1995 13' GLS and will soon be installing a transducer for a depth sounder. I'm told I'm already "breaking a rule" as I'm going to install it on the starboard side of the transom due to where all of the other wiring is at. Due to the trailer/boat lift bunks, and tie down straps for the trailer, space is somewhat limited to begin with. However, I'm curious if anyone else has already "tackled" this problem and found a spot or location that works. Thank you in advance for your thoughts.
whalerron posted 05-15-2002 12:07 PM ET (US)     Profile for whalerron  Send Email to whalerron     
Somewhere on this site, jimh put together an article about this subject. It had pictures and lots of details. I cannot find it under the reference section or anywhere else for that matter. jimh, where did that article go?

- ron

boland posted 05-15-2002 04:00 PM ET (US)     Profile for boland  Send Email to boland     
the transducer should be mounted on the side of the transom on which the propeller rotation is downward when you are running forward. this eliminates the majority of the prop disturbance that poor signals.
KevinW posted 05-15-2002 10:06 PM ET (US)     Profile for KevinW  Send Email to KevinW     
Thanks for the responses thus far. If you Jim, or anyone else knows the location of the "detailed" info with pics I would appreciate it.
Tom W Clark posted 05-15-2002 10:26 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     

Here is the aforementioned article:

The conventional wisdom is to mount the transducer on the port side to counter act the prop torque that can cause a boat to list to port. This is because transducers of old acted like mini trim tabs and could create a lifting force.

In your case this may not apply for two possible reasons:

1) a 13' is so small that you may actually want a little extra lift on the starboard side to help it avoid listing to starboard.

2) Many modern transducers, like the skimmer type that Lowrance uses, do not really contribute any lift.

Contrary to what boland has reported, the other consideration is to put the transducer on the port side if the boat is equipped with a conventional (clockwise) rotation prop so it is on the "up-swing" side of the prop's rotation and less likely to contribute air into the prop's stream and cause cavitation or ventilation.

Again it depends on the transducer you are using, but your idea of mounting it on the starboard say may contribute to this phenomena.

Bottom line is I think you can mount it wherever you want and you'll be OK so long as it's not to close to the centerline of the boat.

jimh posted 05-15-2002 11:21 PM ET (US)     Profile for jimh  Send Email to jimh     
Before choosing a site on the transom for mounting a SONAR transducer, look forward along the hull buttom to be sure there are no strakes in that region of the hull bottom. If you mount the transducer behind a strake there will be more turbulence in the water, and that will degrade the results.

The amount the transducer is immersed in the water had an effect on the performance. Sometimes just another 1/4-inch more immersion can make a big difference.

On the last LOWRANCE unit I installed, I found the skimmer transducer was not working as well as I would have liked; moving it down about a 1/4-inch (the amount of range in the mounting bracket slots) made a big improvement.

I don't know if we can spot fish at 35 MPH, but we get good bottom echoes at that speed.

KevinW posted 05-16-2002 11:16 AM ET (US)     Profile for KevinW  Send Email to KevinW     
Thanks Tom and Jim. You are correct in that it is a Lowrance transducer and it is fairly small (model #564658 used with the Lowrance model 3500 2 3/8" dash mount sounder). After reading your comments and looking at the transom, I think I only have one potential location (maybe two!)on the starboard side of the transom. There is just one strake on each side of the transom. I believe I could locate it about 3" to the right or starboard of the strake or about 7" to the port or left side or the same strake. I need to run the boat and look at it again for turbulance. I would prefer the 3" to right if there isn't too much turbulance from the strake. If I mount it 7" to the port of left of the strake, I am very close to being in-line with the prop. I'll let you know how it eventually works out. It may be a week or two as I have yet to get the docks in, mow, etc. etc. etc! If you have any other words of wisdom let me know. Have a great day.
triblet posted 05-16-2002 05:16 PM ET (US)     Profile for triblet  Send Email to triblet     
Make sure that the transducer will be in the
water at speed. If you get too far off the
centerline, it sees air, so no signal.


KevinW posted 05-30-2002 10:43 PM ET (US)     Profile for KevinW  Send Email to KevinW     
As an FYI: (I'll preface this with the fact that I have only run the boat once since installing the transducer) The location I ended up using to install the Lowrance Skimmer transducer is on the starboard side of the transom. To be exact, the starboard side of the bracket for the transducer is mounted 8" to the starboard of the center drain hole (measuring form the center line of the drain hole). The bottom of the bracket is 1/2 to 5/8" up from the bottom plane of the hull. Obviously there is "play" with the design of the bracket, but this mounts the transducer 7" off the center line with the majority of the skimmer in the water. I have run the boat for a couple of hours this evening and it works great at all speeds. The only time it lost a reading was when I took a purposeful sharp turn to see what the depth sounder would look like with the transducer out of the water. As a final thought, I used 3M4200 in the screw holes for the bracket, as I had some left over from a previous project. The 4200 supposedly will come apart (unlike 5200), but I'm wondering if I should have just used silicon. I lucked out in that the transducer location worked. If it didn't, I think loosening the bracket with the 4200 on the screw holes would have been "fun"!

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