Sounder Probs

[drevil]

I think the transducer for my sounder is too close to the prop. It's about 30cm from the prop and whenever I start moving I get wild readings on the sounder.

What do you think the minimum distance should be between the prop & the transducer?

Has anyone ever mounded their transducer in the bottom of the hull (glass) and kept it inside the boat? I've heard this works well if it is in a fluid, like oil or something, with no airgap between the oil & hull.

[Lucky_Phill]

you should get lots of replies to this one drevil.

Probably mounting your tansducer inside is the best, but, that will deoend on the strength of the signal your unit can put out. Mounting in several ways. Inside container ( PVC Pipe ) filled with some sort of liquid, peanut oil, vegetable oil etc. You can also mount it in a great big dollop of silicone, but in ALL cases, there can be NO air between the transducer, floor and ocean.

Post the type of sounder you have, and I'm sure someone here will have the same and can help you with where to mount it on the outside. As a guide by me, half way between the centre of the keel and the side of the boat. Don't mount it behind any strakes or concave areas. The lie of the transducer should be paralell with the bottom of the boat and I believe it ( bottom edge of transducer ) should be sitting about 10 to 15mm below that line.

But others will differ, depends on the shape of the rig, transducer strength and type. Too many variables.

good luck,


Phill ;)

[clutter]

What type of sounder do you have? Just checked my transducer and it wouldn't be any further than 300mm from my motor and I don't have a problem. Do you have it powered directly from the battery?

Clutter

[Big_Kev]

Doc you will need to clean up a section inside the hull where you want to mount the transducer and make it smooth.
You will need a transducer with a flat bottom face like that of a humminbird.
If you put the transducer in place and weight it down with a brick (carefully) you will then need to fill the hull with water to cover the tranducer ie;no air bubbles between the face of the tranducer and the hull. Then take it out and see if it will work.(dont forget to put the bungs back in lol)
If it does you can mount it in that spot with a big dob of silicone but remember no air bubbles.(drain water from hull first)
If it doesn't work you will need to try a different spot.
Advice is that you can get air bubbles in between the laminates of the glass and this will affect the reading of the sounder.
Hope this helps.
Cheers Kev. #

[bungie]

Save a bit of problems, place a thin layer of bluetack about 3-4mm thick between the hull and the transponder. This removes all the air and lets you move the transponder around with out needing waders inside the boat :)

[drevil]

All good stuff...Clutter, my sounder is a Lowrance X-4 LCG Recorder. I think it's an older model.

[jaybee]

my bro built a wet box, the transducer is in a big dollop of silastic, you then fill the box with sea water. he has no problems except for water temp, takes like forever for the water in the box to heat up to the same temp under the boat. I have my transducer just outside the minimum measurement for the prop due to a bung being in the way, but you get that, however have found running around the bay in shallows, 5mtrs or less it is too damn powerful, but you get that as well, so have thought of the wet box method to solve my problem. oh also i have been told if there is air (bubbles) in the glass where you decide to put the transducer will also affect performance.
cheers.

[Lachie1]

On our old boat when we started moving at any pace (10knts+) the transducer would be out of the water due to being mounted to high on the transom and the displacement of the hull meant the sounder would be out of the water at any speed. Do you think that is the problem. We used to get readings like 368 ft with lots of noise on the screen. Sorry if you dont understand but i will try to post a drawing later.

Lachie

[jaybee]

try lowering the transducer, also make sure there is nothing that can create turbulance in front of it, strakes, bad chips etc. If you go to the web site of your sound you should be able to download mounting instructions and possibly a template.
cheers.

[Big_Kev]

Joe is on the dollar with the mounting without any form of interference in the leading edge of the transducer.
I have also found that to tilt the transducer so that the trailing edge is lower than the leading edge is a must if you wish for the sounder to read at any speed above (as Lachie said above ten knots) and that it the transducer will require an uninterupted flow of water across the face, which requires it to be mounted just beow the planing face of the hull, which eliminates turbulence and air bubbles.
I have found that it is required to make adjustments to the mounting position and angle to get it right on the water.
Cheers Kev.

[drevil]

Hey, guys, I think you might be on to something. I just had a look at the transducer and it's about 20-30mm above the bottom edgo of the hull.

It has been adjusted down as far as it can go, so I will have to move the bracket down a bit.

I know what you mean, Lachie, 'cos as soon as you start moving you would turbulance at the bottom corner of the hull.

Is bogging the old mounting holes with Sikoflex good enough, or should I get some of that 2 part compound instead?

Thanks for your help guys.

[peterbo3]

Doctor 18,
Top of the evening to you. To avoid drilling more holes in your boat, try & fit a small piece of painted marine ply
to your transom using the existing screw holes. Make this big enough to allow you to mount your transducer lower down or to the side.
I have found that the position of the transducer is as per previous posts but you may need to move it slightly several times to get the best readout.
Mark the position of the transducer on the ply with waterproof texta or similar each time you move it so you know exactly where different readouts come from. Took me ages. :-[ :'(

[drevil]

Great idea, thanks Peter. ;)