Can you help me Identify these transducers

Olysan

Member
Mar 17, 2018
113
Boat Info
1994 400 Express Cruiser
Engines
7.4 MPI
Hey guys. I'm a newbie. i just bought a "94 Sea Ray 400 EC. From what i can tell it's had a couple of different electronics packages installed over the years. I have a manual for a Lowrance LMS-350A and a B&G LCD Chart but I don't have either device. I do have a Garmin 421s that came with the boat. I took pictures today of what I believe are 2 or possibly 3 transducers and I was hoping someone could help me identify exactly what they are, if they are thru-hull and if they will work with the Garmin412s. Thanks in advance for your help.
Old transducer.jpg

Port Transducer.jpg
Starboard transducer 2.jpg
 
It looks to me like a Airmar Bronze P120 housing. The transducer is a 800 series. For example a ST800 is a Speed and Temp 800 transducer. DT800 is depth and temp. Airmar makes diferent types with same housing. There is a Mercruiser version, a NMEA 2000 under diferent brands, ets. It all depends on your electronics set up. Another thing you have to look is the angle.
Check for more info:
http://www.airmar.com/productdescription.html?id=104
 
The only electronics that came with the boat was a Garmin 421s. I was able to get it connected and powered on yesterday. I was also able to get it connected to the transducer shown in the 3rd picture above. The garmin new a transducer was connected but would not give me a depth reading.
 
I'm not familiar with the Garmin 421. You have Airmar 800 series transducers. They've manucfatured any number of 800 transducer that fit the P120 housing. When the boat came out of the factory in 1994 came with the P120 housing with a 1994 technology transducer. Since 1994 a lot have changed and several new transducers that fit the same P120 have been in the market. Garmin, Lawrance, B&G, Raymarine, etc don't build any transducer. They buy them from third parties like Airmar. Transducers that work under a network my fit different brands of GPS or MFDs.
You have to figurate out if they are NMEA 183 or NMEA 2000 or another technology. If the transducer that you have installed are NMEA can be used with any GPS multifunction display in a network regardless of the brand.
First make sure what type of transducer you have. If you take a pic of the other end of the cable I might be able to help you. Second if they are NMEA you have to make sure you have the network set up correctly.
 
If there is one xducer that looks like there was part of the hull made for it (probably on the centerline) that was is an oem depth finder and not for the Garmin.

Garmins of that era will have a unique pin out / plug for the xducer and likely only one on the boat will fit your plug. When testing, consider that if the xducer is not in water it will provide no reading. It has to be in water to test it. Also, if the xducer is turned on when dry it can overheat and be damaged.
 
Thanks guys. That info is very helpful. One of the sensors does have the correct connector for the Garmin, but It doesn't seem to be working. Next question...can i remove and replace those without hauling the boat? I looked at Airmars website a bit and it seems to indicate that I can. I also think that there is a "blanking plug" hanging in the bilge.
 
Yes, if it has the blanking plug. It's is designed for that. Just be prepared for the trasducer sized jet of water when you take out the transducer. The prospect is a bit scary to me, and I think I'd want to practice on land first if I could.

Here's a video of someone doing it with a paddle wheel sensor.
 

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