Re: Replacing Sonic Speed Log



I have done almost exactly what you ask about.  I put a CS4500 in the old depth transducer hole (the hole will need to be enlarged a little), and used a P79 to supply depth data.

I did not connect the CS4500 to the Hydra, but rather it feeds data into my NMEA2000 network. 

I have nothing bad to say about the CS4500.  It works as well as the sonic speed sensor, and is much less susceptible to electrical interference.  Our sonic speed goes bonkers if we turn on the inverter, for example.  The only time I had any inaccuracy with the CS4500, was because there was some growth on the hull just in front of it which diverted the water flow from the sensor.  If you put some transducer paint on it, it requires minimal routine cleaning--unlike a paddlewheel.  You can find many negative comments about the CS4500 online, but few of those commenters actually have used one, they are just repeating boatyard scuttlebutt.

The P79 works well for navigation depth data, I got good readings down to 150 to 200 feet.  On my old boat I got much better results from a P79.  A different hull thickness/composition probably.  I do a lot of fishing, so I have found the performance of the P79 as a fishfinder to be marginal on the Amel, but it works fine to keep me off the rocks.

Paddlewheels, the CS4500, and the sonic speed sensor all use the same standard protocol to transmit speed and distance data.  They send so many "pulses per mile", (like a spinning paddle wheel) the exact number I have forgotten, but you can find it in Airmar technical literature if you want to know.  (40,000 sticks in my mind, but don't count on it!)

Bill Kinney
SM160, Harmonie
Bar Harbor, Maine.

---In amelyachtowners@..., <coastalseas@...> wrote :


I have a SM2000 with a faulty (read dead) B&G sonic speed sensor.

I am looking to replace it with another sonic speed sensor, my questions for the forum are:

1. Has anyone used a CS4500 airmar transducer in the 2001 vintage B&G through hull depth fitting? 

2. Any negative experiences with the CS4500? 

3. Will the original B&G Hydra 2000 accept the signal from the CS4500 without additional interface parts etc. 

To avoid drilling another hole in the hull, I am looking into using a second in hull depth transducer "P79" to provide basic depth data.  

Many of you are using a Tri sensor (speed/depth/temp) in the original depth fitting, but these have a paddle. There is a new DX900 sonic tri sensor being promoted but it's not cheap.  Hence my interest in the CS4500.



Lady Annabelle Hull #339

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