Please Help with Finding a Good Transducer Location (Pics of Transom attached)

[ERock82]

I am trying to figure out where to mount my transducer for my new Lowrance Elite 3X Fish Finder. I am attaching 2 pics of my transom with pin points on them. The red circles are what I believe to be the strakes and was told to avoid them. I was also told to avoid the bunk areas. I would ideally like to place this on the starboard side. I have 4 colored stars which I believe to be possible locations. I have also marked the water line in blue. If someone could tell me which colored star would be the best spot or a spot that can reference a location on the transom, that would be great. I am guessing at that 15" distance. I do know that the stainless steel transom trim is exactly 24" long, so that is how I got the 15 inches. I was also told the transducer should be about 15" horizontally from the prop edge. My boat has only a 6 ft beam so there's not a lot of options if I really have to be 15 inches over. The area with all of the stars is completely flat.

On another note, I would really prefer not to drill any more holes in the transom and would just like to send the trans wire right up over it like the speed pitot wire and go through the sleeve (circled in orange). Is there any problem with this? I see a lot of people drilling a hole and sending the wire through but it seems like that is mostly for appearance reasons.

Thanks in advance!

 

[alldodge]

I will suggest where your purple star is, or the green one as second choice. No problem leaving the wires on the outside and over the top. To mount I would suggest gluing a block to the hull with some 3M 5200. This way no more screw holes in the hull. make sure the block is flush with the bottom edge.

 

[fhhuber]

Yep to all of above..

If you decide to drill the transom.. drill well oversize and then glue in dowel plugs with epoxy. Put the screws in the dowels. Then the dowels might rot from water exposure but the transom is protected by an epoxy barrier.

The advantage to drilling and plugging is... you will be core sampling the transom to check its condition.

Indications of a lot of age to that hull... the core sample might be a good idea.

 

[dingbat]

You can't locate a transducer by looking at the transom alone. You need to look at the bottom of the boat for sources of turbulence. No steps, strakes, rivets, etc. in front on the transducer

 

[ERock82]

Results from testing new fish finder (pic attached)

I tested my fish finder yesterday with a piece of wood clamped on the transom to try and get a good transducer mounting position. I tested the area of the purple and green stars (pic attached that was in previous post). I was limited to those positions with the way I was able to clamp on the board.

It worked great at slow speeds and seemed accurate but when I would go over about 10mph I would lose the depth readings. Sometimes I would get them back intermittently and they would be good but sometimes they would say crazy depths like 150 feet in a 10ft river. Also, I would be riding along at idle no wake speed and would get 2 to 3 ft showing up right after 15ft where I knew it was around 10-15ft. It would correct itself after a moment.

The river I was on was pretty smooth. There are a few things I can think of here:

1.) The block of wood was a 2X3, so the transducer stuck out a couple inches off the boat.

2.) The board was clamped tight but maybe it was vibrating bc it was not permanently mounted on??

3.) The green and purple stars are only 8 to 10 inches from motor. 15" is recommended but if I were
to go over that far I may be too high on transom.

4.) I probably could have had the trans sitting maybe an inch lower and I could always angle it down.

5.) Maybe the problem was too much turbulence from motor.

Questions:

1.) Should I just try mounting it at the purple star but as low as possible and tilt it a little lower then level?

2.) Should I try mounting it at the orange star or to the right of the speed pitot which is over the bunk?

I feel like the black star would be too high up although it would be 15" from motor.

Any advice is appreciated. Thanks.

 

[ondarvr]

Since we don't have any pics of the transducer position when mounted, there's no way to tell exactly, but...

The transducer needs to be in the water at all times, the erratic readings are from air and turbulence in the water. Without knowing more the answer would to lower it down so it it's in the water at all times. The directions should indicate the correct angle for it.

 

[fhhuber]

Sometimes a very fine line between working correctly and getting a rooster tail off the transducer that splashes into the boat over the transom.

 

[jbcurt00]

Erock
Merged topics

Really continuation of previous topic about location.

Good luck setting it up.

 

[ERock82]

I'm not satisfied with the results over 10mph at the green or purple stars so I really have one other option. The orange star.

I can't mount to the right of the pitot because there is a bunk sticking out.

Do you think the orange star is too close to the motor?

I could always place the pitot where the purple star is and put the trans where the pitot is. Seems like that wouldn't make much difference from just mounting at the orange star?.

 

[ERock82]

Testing completed on transducer locations

Ok, so I have finished testing all locations on my transom. Nothing was perfect or even great but the best result seemed to come from orange star (directly left of speed pitot). At all of the other stars it would work great until I went over 10mph and then I would lose my readings. If I tried to adjust it to sit lower on the bracket I would get a rooster tail.

On the orange star I went up to 35mph for an entire minute without losing reading. I lost it for a few seconds then got it back, then got random readings of ridiculous depths. When I would slow down I would usually get it back and it would hold for awhile at speed. It's not great by any means but better than the other locations. I think I will just settle there.

Now, I was unable to test directly to the right of the speed pitot because of placement constraints on my board I clamped. There is a bunk there but I took measurements and it shouldn't be a problem to mount there?..I think. There is about a 1 inch space before the transducer would hit the bunk when boat hits bow stop on trailer. Please let me know if I'm missing something here.

My only concerns about the orange star is that it is right next to the motor. I think it worked best though because it is at the lowest point on transom. The bunk would be about an inch higher but much lower than the purple and green star locations.

Do you think I should just mount it directly to the right of pitot over the bunk or just go with orange star?

Either way, I'm done testing and am going to mount this thing now.

 

[roffey]

I had the same type problems and it was the transducer was lose and was moving. The faster I went the more it moved up. I was on a river and getting hundreds of feet. I screwed it down, then it had a roster tail so I moved it up a little. Not saying that is your problem but might be worth checking?

 

[jbcurt00]

Erock
Merged topics

Really continuation of previous topic about location.

Good luck setting it up.

Again

 

[JimS123]

On your diagram the purple star is the only possible location. If it didn't work there its not the location but the installation.

Make sure the lead end is perfectly flush with the bottom of the boat, or just a fraction below. Angle the trailing end downward ever so slightly to ensure the water is flowing smoothly across the bottom of the transducer. Fill the gap between the transducer and the hull with slicone to in effect make the hull and transducer one.

If you don't have a flat transducer (and thus my suggestions make no sense), post a pic of the transducer.

If all else fails, follow the installation instructions in the installation manual. They all have pictures on how to do it.

 

[ERock82]

roffey made a very interesting comment about the transducer moving.

I used the wood block technique and clamped a 2x4 to the transom to test the locations.

Could it be that the bottom of the 2x4 where transducer was mounted was lifting about 10 degrees upwards when at speed??

Being that it was only secured at the top of the transom by a clamp, it could have possibly lifted on the bottom. Maybe that is why I got bad readings on the purple and green stars???

Maybe it lifted too high up on purple and green, BUT orange was so low down that it didn't affect it that much when it lifted.

Just a thought?