Humminbird PiranhaMax 150 temperature connection

I apologize in advance if this is a bit off topic... it probably belongs on a fishfinder forum, but I can't find one with smart people like on this forum, so...

I'm installing a Humminbird PiranhaMax 150 on my Revo 11, and I bought a In-Hull Puck transducer, which I will epoxy to the inside of the hull, probably somewhere just behind the seat, accessible through the rear hatch.

Conveniently, the puck transducer comes with a separate temperature sensor which can safely wire out through a small hole in the back of kayak and into the water for accurate temp measurement. Both transducer and temp sensor connect to the head unit with the same 7-pin connector. The temp connector wire comes out of the transducer (it's not a separate connection).

The head unit has 3 rear connections. Power. Transducer (+ temp). And Temp alone.

My question is, why is there a separate temp input in the head unit? And since I won't be plugging anything into it, will that compromise the waterproofness of the unit? Since I'm mounting it in the sail mast post, it will get splashed on from time to time.

Thanks for any input!

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2011 Oasis - Lunalilo Express
2012 Revo 11 - Lunalilo

Not all transducers have a temperature sensor. In case a person wished to have it Hummingbird sells just the temperature sensors alone rather than forcing a person to buy a different transducer just for the temperature sensor.
The unit is still waterproof if you don't have all the plugs connected. Though I recommend putting some dielectric grease on all the connections to keep any corrosion to a minimum on the pins as a precaution.

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MrGreen

Ah, makes sense.

Dielectric grease? Hmmm, I'll have to look into that. Sounds like a good idea.

Thanks!

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2011 Oasis - Lunalilo Express
2012 Revo 11 - Lunalilo