Problem with sonar losing signal

[MAC ATTACK]

I have a brand new Garmin GPS740 and the Airmar P66 transom mount transducer. The problem I am having is losing my sonar (and depth if using GPS) signal when getting on plane. If I recycle the power once on plane it usually comes back. I love the set up, having both GPS speed and the tranducer wheel speed, water temp etc., but the transducer is big for a transom mount.

I relocated the Xducer about 1 inch lower into the water. The only way to change the angle in the water is with a wedge that comes with it (it does not swivel like most as it is a breakaway type mount). I set it up as I have several others, just wondering if there is anything I am missing.

Normally I fish in waters that I am familiar with, but I also fish the flats with tide changes. Getting on plane to fish different spots gets hairy when it is 3 or 4 feet of water.

It will read the bottom and depth fine at speed (35 knots).

Any advice at all would be appreciated. The transducer is located on the starboard side of the transom exactly where the old one was, and there are no hull interferences in front of it.

 

[dingbat]

Re: Problem with sonar losing signal

The problem I am having is losing my sonar (and depth if using GPS) signal when getting on plane. If I recycle the power once on plane it usually comes back.

explain in more detail. Sonar and depth are one and the same. What does recycling the power mean?

The transducer is way to deep. Should extend only 1/8" below bottom of hull on short side. How far off the prop are you?

The P66 is pretty small compared to other transducers. Mine is 4" in diameter and 6" tall. The transom mount B258 is the size of a brick

 

[MAC ATTACK]

Re: Problem with sonar losing signal

You are right, the depth I was referring to was the reading in the corner when using my GPS map. Recycling the power is turning the unit off and back on again. Relocation was done due to losing the sonar at any speed on plane. When I moved it lower it got better, but still loses it when getting on plane. I have tilted the motor all the way down and still have significant bow rise during planning, but it does plane out quickly.

Wow, I thought my transducer was big! Thanks for the reply

 

[dingbat]

Re: Problem with sonar losing signal

Once you loose depth, will it come back on its own if you shut down let the boat come to a rest?

 

[MAC ATTACK]

Re: Problem with sonar losing signal

Yes, if i back down or stay on plane for a while it will come back

 

[dingbat]

Re: Problem with sonar losing signal

Dirty water. Need to move transducer to clean water. Pictures?

 

[MAC ATTACK]

Re: Problem with sonar losing signal

I will get some, basically you are saying a relocation?

 

[tazrig]

Re: Problem with sonar losing signal

The transducer can only read through water not air. If the bottom of your boat isn't smooth and or you are located too close to your prop you will create turbulence with air bubbles and your transducer won't be able to read. You need to find a turbulence free zone far enough away from your prop to allow for turbulence free water flow at all speeds.

 

[dingbat]

Re: Problem with sonar losing signal

I will get some, basically you are saying a relocation?

Most likely...you have something going on coming out of the hole. Could be something as simple as the transducer isn't "tilted" correctly.

Here is the installation instructions for the P66
http://www.airmartechnology.com/uploads/InstallGuide/17-247-03.pdf

 

[MAC ATTACK]

Re: Problem with sonar losing signal

Thanks, those are the same directions that came with it. I followed them to the "T", then I lowered the Xducer into the water a little after losing sonar at any speed above idle. I have ruled out being too close to the prop, as when I do have sonar it works fine at idle and at speed. I am only losing sonar during planing, which leads me to believe that the transducer angle might be the cause. The only way to adjust it is with a shim, and then when the boat is sitting the leading edge of the Xducer would be lower in the water.

Maybe time to upgrade to a thru-hull...........

 

[bruceb58]

Re: Problem with sonar losing signal

You need to look over the stern of the boat when you are on plane and look at the water around your transducer to see if you have good clean flow of water.

 

[MAC ATTACK]

Re: Problem with sonar losing signal

Will do that. After researching for a while I think I figured it out. The Airmar P66 apparently is not as good as other transducers in water less than 30'. According to several other boards this seems to be an issue, unless used mainly for trolling or situations where the transducer angle does not vary much. If I am in 12' of water and am using 200 kHz the cone is very small, therefore when I plane out it loses the return signal. I will test again at 50 kHz and try to keep the bow lower with power and trim.

Maybe I am grasping at straws...... I have excellent signal return both trolling and at speed which tells me I am not in dirty water either time. I have used this transducer location with other transducers and never experienced this issue (have a fiberglass mounting plate epoxied to the transom). I followed the Airmar instructions to the letter.

The only thing I can think of after researching is that my bow is rising high during plane + small cone which equals small area of return + water less than 30' sometimes less than 6'.

Am I getting anywhere? I might buy a separate transducer and switch depending on the type of fishing. Hate to do that but I also hate losing signal during low tide or lake navigating in unknown territory.

 

[jhebert]

Re: Problem with sonar losing signal

I, too, recently installed an AIRMAR P66 transducer on the transom of my outboard-powered boat, and I also have observed problems with the operation of the transducer when the boat is on-plane. The P66 seems to be quite sensitive to its mounting location and the amount of immersion in the water.

To test your present transducer position to see if the cause of the problem is related to immersion in the water, try this procedure:

--when on plane and experiencing problems with signal return from the P66, turn the boat in the direction that will tend to push the transducer deeper into the water. For example, if the transducer is mounted on the Starboard side of the transom, turn to Starboard. This will push the transducer deeper into the water.

--if the signal improves when making a turn that puts the transducer deeper in the water, the transducer is probably not immersed enough in the water in its present position. Move its position down and test again.

--also try a turn in the other direction, to reduce immersion. If the signal improves then, the transducer is too deeply immersed. Try raising the transducer slightly and test again.

Using this procedure with my AIRMAR P66 I have found that its present mounting was not deep enough. It worked better in a turn to starboard which caused it to be immersed deeper than it did when going ahead. Turning to port caused a decrease in the return signals, indicating the transducer was not immersed properly.

 

[agallant80]

Re: Problem with sonar losing signal

I have the same problem with my Lowrance. I wish I could move it but I don't want to leave holes in the transom where it was mounted before.

 

[MAC ATTACK]

Re: Problem with sonar losing signal

I, too, recently installed an AIRMAR P66 transducer on the transom of my outboard-powered boat, and I also have observed problems with the operation of the transducer when the boat is on-plane. The P66 seems to be quite sensitive to its mounting location and the amount of immersion in the water.

To test your present transducer position to see if the cause of the problem is related to immersion in the water, try this procedure:

--when on plane and experiencing problems with signal return from the P66, turn the boat in the direction that will tend to push the transducer deeper into the water. For example, if the transducer is mounted on the Starboard side of the transom, turn to Starboard. This will push the transducer deeper into the water.

--if the signal improves when making a turn that puts the transducer deeper in the water, the transducer is probably not immersed enough in the water in its present position. Move its position down and test again.

--also try a turn in the other direction, to reduce immersion. If the signal improves then, the transducer is too deeply immersed. Try raising the transducer slightly and test again.

Using this procedure with my AIRMAR P66 I have found that its present mounting was not deep enough. It worked better in a turn to starboard which caused it to be immersed deeper than it did when going ahead. Turning to port caused a decrease in the return signals, indicating the transducer was not immersed properly.

Thanks, excellent advice but have done that. That is what led me to lowering the transducer already. My signal improved on plane when turning starboard, so I lowered it. Now I have excellent signal both trolling and on plane, but it loses signal when planning out. It will regain signal after a while, but sometimes it takes way too long for my comfort level.

I appreciate all of the advice/tips.

 

[dingbat]

Re: Problem with sonar losing signal

After researching for a while I think I figured it out. The Airmar P66 apparently is not as good as other transducers in water less than 30'.

Actually, the opposite is true. The P66 is 3-5 times more sensitive than your typical "stock" transducer. It's like buying a super sensitive microphone then saying it doesn't perform well because it picks up too much background noise. Get rid of the background noise and the performance will be impressive.

If I am in 12' of water and am using 200 kHz the cone is very small, therefore when I plane out it loses the return signal.

Do the math...speed travels thru water at almost 5,000 ft. per second. In 12' of water, the signal would take 0.0024 seconds to complete the round trip. At 60 miles per hour (88' per second), your boat would have traveled 2-1/2". At 30 mph, you've moved 1-1/4". How big is that cone angle again? :facepalm:

The only thing I can think of after researching is that my bow is rising high during plane + small cone which equals small area of return + water less than 30' sometimes less than 6'. Am I getting anywhere?

Not really. The math doesn't work (see above) but to test your theory, run 50KHz (45 cone angle) and see if the problems goes away. I'm betting it doesn't

Still waiting for a picture of your location. A screen shot showing the problem would be even better.

Are you running the unit in manual or auto mode? Most machines perform miserably in auto mode.

 

[MAC ATTACK]

Re: Problem with sonar losing signal

Actually, the opposite is true. The P66 is 3-5 times more sensitive than your typical "stock" transducer. It's like buying a super sensitive microphone then saying it doesn't perform well because it picks up too much background noise. Get rid of the background noise and the performance will be impressive.

Just going by what other boaters are saying on other boards

Do the math...speed travels thru water at almost 5,000 ft. per second. In 12' of water, the signal would take 0.0024 seconds to complete the round trip. At 60 miles per hour (88' per second), your boat would have traveled 2-1/2". At 30 mph, you've moved 1-1/4". How big is that cone angle again? :facepalm:

Not referring to speed and out running a sonar signal. I was referring to cone size at 200 kHz, angle of my boat during planning and shallow water. I may be from Georgia but I don't think my boat is that fast.

Not really. The math doesn't work (see above) but to test your theory, run 50KHz (45 cone angle) and see if the problems goes away. I'm betting it doesn't

I will test it. In shallow water a 45 degree cone size has to reduce the chance of losing signal over an 11 degree cone size with these factors- Shallow water, angle of boat during plane, size of cone for return.

Still waiting for a picture of your location. A screen shot showing the problem would be even better.

Are you running the unit in manual or auto mode? Most machines perform miserably in auto mode.

I will test both, thank you so much for the replies!

 

[Fed]

Re: Problem with sonar losing signal

I think you need half a shim.
When I installed mine I was in the same situation, no shim too much angle, with shim the leading edge would be too deep.
I went with too much angle and was lucky enough to get away with it but I bet it's very close to suffering the same problem that you're having.

If you take some pictures make them meaningful.

 

[MAC ATTACK]

Re: Problem with sonar losing signal

Thanks, I will take photo's when I can get home before dark. Looks almost exactly as yours except not quite as steep of an angle. I might try to go out and shoot one tonight with a flashlight. Maybe I will try to grind the shim and try that. Thanks for the input, never thought of "half" of a shim!

 

[MAC ATTACK]

Re: Problem with sonar losing signal

Best I could do for tonight.