Water temp. Sensor

[Elemental]

I'd like to built a sea water temp monitor (largely because I can and my plotter will accept a NMEA temp sentence, rather than any real need). I have worked out how I'll do everything except for mounting the temp sensor (LM35). I don't want to go drilling holes in the hull, nor do I really want a wire clipped to the transom/bathing platform (although I guess I could tolerate that). I was wondering whether I could bond a sensor to the hull interior or a skin fitting in some way - or would the sensor just show air temperature...?

 

[Even Chance]

I have a Garmin 140 sonar, and it shows water temp with the transducer bonded to the inside of the hull. It is reasonably accurate, cos I checked it with a Fluke temp unit that was calibrated. Its a whopping 9 deg C up here at the moment!!