Sensor on Transom?


New member
I'm looking at buying this 2005 Nitro. I'm not a big fan of drilling on boat hulls and transoms if at all possible. (I know..outboard, and other bolted items from the factory which is apart of it) So the owner sends a pic of the "transducer" (attached) when I asked about it. He said it came from the factory like this. When I first saw it I thought, I've never seen a transducer like that, but thats not always saying much. To me it looks more like a temp sensor maybe for a thru-the-hull transducer? Anyway, the whole point of the picture was to see, as much as possible, what the condition of the mount/screws were in. Again, I've never been entirely comfortable with drilling into a hull/transom. I immediately start thinking of filling/glassing/gel coating. But its not easy, apparently, to find a used boat without a transom mounted transducer. But this doesnt look bad. I'm just not sure what it is, if its not a transducer. The depthfinder is a lowrance. Thanks for any feedback!


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Active member
I say you are right identifying it as temp sensor. If you are concerned about the holes in the hull, back out the screws, and fill the hole with 3M 4200 sealant. Dab some around the screw head before tightening down. After the 4200 sets, about 24 hrs., you are good. I never had an issue with water intrusion using sealant. Did the boat owner say whether or not the transducer was shoot through the hull ?


New member
Thanks for the info. Good to know. He mentioned this was the transducer and this was all there was. I asked him that specifically. So I'm thinking it has to be through the hull. I'll know more after the weekend. I did, however, do some searching and found a lowrance temp sensor that looked identical online. So that helped me. Thats why I'm also thinking its through the hull since without a sensor below the waterline, you're not going to get temp readings. He's had the boat for 3 years and has only taken out 4 times he said. So he apparently hasnt modified anything that I know of. I guess that can be what makes me a little nervous is you dont know how appropriately this was installed if not by the factory. But it looks like there is epoxy or a sealant of sorts around the screw. I've seen others that looked like it was a rotten transom waiting to happen. Thanks again!!
That is the water temp sensor for the thru hull transducer. My boat came with factory installed lowrance 7 inch units. The unit at the console used only a thru hull transducer, and thus had the water temp sensor like the one pictured. If the units were factory installed, I wouldn’t worry about it or touch it. Just leave as is and when you upgrade units you can always install a SI/DI transducer on your jackplate.

I would be more concerned about that place in the fiberglass near the top of where your jackplate is bolted to the boat (second pic). Hard to tell from the picture but looks like fiberglass flacking off to me.


New member
Thanks for the information. I was wondering about that. Not having seen it in person (cpl hours away) yet I've had to rely on pics. I'm planning to go tomorrow. Nevertheless, I'm going to ask about it before going. I was hoping it was epoxy or some type of adhesive that is stained. But it was a red flag. Thanks for mentioning it...AND thanks for the mentioning about the factory installation. That does put me at ease. I would rather just leave it in place.

Speaking of the temp sensor, would it make sense to add a sealant around the bolted area? Just cover it up with epoxy or a sealant of sorts? Maybe overkill? Just thinking.

Thanks again!