Depth finder

[Mhiggi]

I have a piranha max 153 depth finder reads fine while idling, when pick up speed depth goes to zero

 

[Jeep Man]

Possibly a break in the transducer cable, but more likely due to poor location of the transducer. If it is located in the turbulent water from the prop wash,it will not read properly. Temporarily relocate to a piece of 2x2 and clamp it to the transom and locate it deeper. this will prove the solution.

 

[Texasmark]

Water has to be in contact with the bottom of the transducer to get a reading. You are transmitting sound waves and air is too thin to adequately transmit them. I installed mine inside the boat just in front of the transom. Use epoxy as it gets hard, helps in the transmission vs something soft like RTV. Bubbles attenuate the signal so minimum bubbles in the adhesive.

This cuts down on interference and reduces the opportunity for damage from people or logs/stumps etc. You probably can go faster too and still get a good reading of the bottom. I've done it on several boats and works for me.

If you have a temp setup in your system, my last systems had that option. I had one connected to a transducer on the bottom of my trolling motor and the other inboard mounted as stated. The difference in temps between the one in the water and the one in the boat was usually about 2 degrees. So there is some error involved in the inboard mounted one but 2 degrees out of 80ish.....doesn't bother me.

One last thing is ensure that you have a solid medium between the ducer and the water. If you have a foam filled glass hull or balsa wood it attenuates the signal. Find a spot where you have solid glass or alum.

Mark

 

[Jeep Man]

Possibly a break in the transducer cable, but more likely due to poor location of the transducer. If it is located in the turbulent water from the prop wash,it will not read properly. Temporarily relocate to a piece of 2x2 and clamp it to the transom and locate it deeper. this will prove the solution.

 

[lakegeorge]

You might try adjusting your sensitivity setting, a lot of depth sounders just don't read when you are going fast, I don't think the sonar can pick up the sound waves fast enough.

 

[airshot]

While I am not familiar with your particular model I have had that issue with other models. Normally this is caused by the transducer loosing the bottom at speed.
This is usually caused by air bubbles crossing the face of the transducer and of course they need a solid water column to read properly. I have an aluminum boat so getting the transducer between rows of rivets was critical as these rows cause a disturbance and air bubbles. Depending on your transducer type it needs to be slightly below the bottom point where it is mounted, by slightly I mean anywhere from 1/16" to mabey 1/4" max. This will require some experimenting on your part.
Many times the transducer needs to be angled slightly forward so the water coming off the hull creates a solid wall of water crossing its face, by tilting it back ward air bubbles will be created and you will loose the bottom. Be sure you have a high speed transducer, most newer models are but some are designed for low speed operation only. Also be sure the transducer is not inline with a rib on the bottom or anything else that would cause a disturbance in the water flow streaming from the hull across the face of the transducer. In some rare instances I have had to add some epoxy resin (bondo) to smooth the transition from the hull to the transducer face to prevent air bubbles. Start with a straight edge running from the hull where the transducer is mounted across the transducer face, it needs to be slightly lower and tilted slightly toward the bow to catch a smooth stream of water coming off that hull. Hope this helps.........

 

[airshot]

This is a double post, unfortunately I have responded to the other post, hopefully the moderator can add my post to this post and delete the other so as not to confuse others. Thanks

 

[GA_Boater]

This is a double post, unfortunately I have responded to the other post, hopefully the moderator can add my post to this post and delete the other so as not to confuse others. Thanks

Done

 

[edthearcher]

as airshot mentioned my directions say fiber glass boat put transducer level and even with the bottom plane of the boat, on a metal boat should be mounted 1/4 to 3/8 below the boat. as said than if a problem arises from bubbles adjust up or down slightly, on my 22 foot sea ray it reads clear at 50 mph

 

[Texasmark]

On speed, the two transmitter "carrier" frequencies in use today, of which I am aware, are 50 and 200 kHz and transmitted by a percussive instrument (the pizoelectric crystal in your transducer), meaning sound waves. Electrical waves make it vibrate sending out sound vibrations and the received sound vibrations (coming back) make electrical signals. That's also the reason you can mount your transducer inside a metal boat that would block the signal if it were radio waves like you get over the air (TV, Internet, Satellite).

The reason for the different frequencies is probably so that you can use two different instruments on one boat without interference, or reduce the interference that might be experienced in a fleet of boats, since one is tuned to receive echos from one freq. and the other the other. Also in deep water applications, the lower frequency may provide better results due to electronic characteristics of the wave, or just do better in recognizing certain sized/density objects. Just a guess....never researched the reason. However sound travels at about 600 mph or 880 ft/sec, (your car travels at 88 ft/sec at 60 mph) regardless of the electrical carrier frequency. Just a tad faster than your boat. So the better responses we get today are just due to technology improvements and boy those things are happening so fast you can't keep up with them.

Didn't have anything else to do this morning so I thought I would exercise my jaw.

Mark

 

[drrpm]

If it worked well in the past then the positioning is alright and its likely due to a loose transducer. The speed of sound in water is significantly faster than in air.

 

[Texasmark]

If it worked well in the past then the positioning is alright and its likely due to a loose transducer. The speed of sound in water is significantly faster than in air.

Well I looked it up since I was just shooting from the hip to make the point that his boat was in no way outrunning the sonic reply. So air is not 600 mph but 767 in dry air at 20 degr. C and in pure water is 4.3 x faster according to Wikipedia which just makes my point that much more valid.

Thanks,
Mark