Choosing A Transducer

[ken52]

Looking at getting a new gps/sounder. Garmin seems to be the only one that has two types, one includes speed,temp & depth at a higher price the other is depth & temp. Am I wrong but I thought the gps part gave you speed even if you didn't have a transduce installed? any help on this is appreciated.

Kenny

 

[j_martin]

Re: Choosing A Transducer

Back in the good old days, about 3 years ago, some transducers had a paddle wheel to determine speed, and relay it to the depth finder for charting control.

If you get a modern combo unit, you don't need the speed wheel. Temp is very helpful, and if you're going to be in deep water and have a dual frequency sounder, a dual frequency transducer is needed. With Lowrance, anyway, the regular depth/temp transducer works well in 100' water. If the Bass I go for are any deeper than that, I quit.

 

[ken52]

Re: Choosing A Transducer

Thanks J_M. I'm looking at modern combo's. I have another post about help choosing one of three unit I'm lookig at.

 

[sschefer]

Re: Choosing A Transducer

There are two speed measurments that are available. Speed over ground (GPS) and speed over water. The paddle wheel style speed indicators are intended for trolling speeds over water while the pitot tube styles are intended for speeds above 5mph. Most paddle wheel units also include a temp sensor. None of these will give you depth. In order to get depth you must use some form of sonar. Some sonar transducers also include surface temperature reading abilities. Some are single frequency and some are dual. If your head unit is capable of reading dual frequencies then you would be wasting your money if you didn't get a dual frequency transducer.

My Lowrance HDS-8 has all the bells and whistles but I suspect you are just looking at the gauge style units. Is that true? If so, then check with the manufacturer and buy the correct transducer and gauge that corresponds with the type of boating you do most. Most boaters that use these types of gauges don't care if the water is 200ft deep but they get really concerned when it's less than 4. If you fall into that category then a single frequency 200mhz transducer will probably be fine. You may or may not need a GPS antenna for your gauge. Some have them built in and others don't.

 

[ken52]

Re: Choosing A Transducer

Thanks Steve. Actually one of the units I'm looking at to replace my gps/sounder is the HDS-7 w/50-200Khz transducer. for some reason Garmin offers a transducer with speed,temp, depth and then another one with temp & depth.

 

[dingbat]

Re: Choosing A Transducer

Thanks Steve. Actually one of the units I'm looking at to replace my gps/sounder is the HDS-7 w/50-200Khz transducer. for some reason Garmin offers a transducer with speed,temp, depth and then another one with temp & depth.

Two issues, need and cost.
Speed over water is only an issue if in tidal water or on a river. They become redundant on a lake or pond.

The transducer w/ speed costs 40% more than w/o. Why make the mfg. pocket fatter if you don?t need?

 

[ken52]

Re: Choosing A Transducer

Good point Dingbat. I will be in tidal water in and around the Gulf(West Central FL). It only appears that Garmin offers it in both variety.

 

[dingbat]

Re: Choosing A Transducer

A sounder is only as good as the transducer attached to it.

There is no need to buy an OEM transducer other than the one-stop shop convenience. There are a lot better transducers to be had.

 

[ken52]

Re: Choosing A Transducer

Dingbat, what type of frequency should I look for, again I'll be fishing in water 25' max more than likely? It seems the OEM are 50-200KHz. I'm aware of Airman transducers, how do these rate?

 

[dingbat]

Re: Choosing A Transducer

Airmar makes a lot of the OEM transducers. The Airmar P66 is the "tri-ducer" being offered by Garmin with TMP, SPD. Airmar builds a range of products ranging from OEM to State of the Art. The only limitation is your pocket book.


To me, the depth of the water is irreverent when selecting a transducer. I want every trick in the box at my disposal if I need to use them.

I use 50 kHz a lot. Even in ?shallow? water. With its wide field of view (4 times larger than 200 kHz.) it makes a great tool for covering a lot of area in search mode or while trolling. Yes, the sensitivity is reduced but to what end? A 200 kHz produces a resolution of 0.29? (1/4?) while 50 kHz produces a resolution of 1.15?. I could see the resolution being a issue if you were looking for minnows, but hardly an issue if your fishing for anything worth catching.

 

[ken52]

Re: Choosing A Transducer

Thank you for the explaination. I didn't fully understand that whole frequency thing to be honest. It's nice to know others are willing to teach and help others that are trying to learn more. Thanks again Dingbat.

 

[dingbat]

Re: Choosing A Transducer

This will tell you everything you need.
http://www.airmartechnology.com/uploads/installguide/Theory_of_ Operations.pdf

 

[ken52]

Re: Choosing A Transducer

Thanks Dingbat, great piece of information.