What are these things?

[Bigjim]

Attached are a few photos of some instrument sensors attached to the hull below the water line. The one with the orange wire is a speed log. One of the others is a depth sounder. I removed the gauges for each sensor last year because none of them worked.

I have Raymarine sensors to replace them with but I was wondering if the sensors themselves still worked. I have a Raymarine analog to digital converter and wondered if it could be used. But it doesn't look good. The wires are not standard.

Anyone have a clue or suggestion?

[tkeithlu]

My bet is that in the third photo the nearest sensor is the original depth sounder and the middle one is a later addition depth sounder. It may have been simpler to leave the old one rather than removing it and then plugging the hole because the newer one is smaller.

If I were faced with this and already had paid for a new depth sounder sensor, I wouldn't mess with it - I'd replace the sensor and move on to the next project.

[BenBowSirocco]

tkeithlu makes a great point. If you own it, see if you can put it in one of the existing holes.

But just for the sake of conversation. I had great luck hooking my "old" depth sensor to a new unit by cutting the wires and properly solder splicing them to an ebay purchased "sensor cable extension" for a new "Sounder" display. So if you have not purchased a new sensor yet- this may work for you as well.
Depth sensors have a frequency they use to ping the earth with and the "Depth Sounder" display has to be able to interpret/use this frequency. There is a year were the commonly used frequency changed and is still used today. I have forgotten all of the numbers that went with that information. But if you remember what you removed from the boat last year- you may be able to track down the frequency used by that unit- and then check what frequency your new unit requires.

Last 2-cents: properly glassing over a hole in the hull takes a bit of care, but is a very simple process. I personally repair every hole below the water that I am not in need of for piece of mind. The plastic ones are especially concerning to me as I feel their wall thickness of the threaded end is always rather thin looking. Although Im sure smarter men than I made the decision what was "safe" for their money..

[tkeithlu]

I think that all the common transducers are 200 KHz, but more recent models have 200KHz for shallow water and 50 KZ for deeper, usually down to 600 ft/180 m. My limited experience has been that most sensors work across models, so Ben makes a good point.

[Bigjim]

I read several documents that recommended using a thru-hull setup for a depth sounder. The plan is to affix a PVC pipe to the interior of the hull fill it with mineral oil and then install the depth sounder inside the boat without drilling a hole.

Has anyone tried that type of configuration?