Electronics - corrosion protection

Tried to find answers to my questions on previous posts but can't seem to find one.
I have a Lowrance Elite 4 and have the following questions:
1. What product would you advise to spray into the transducer/power plug to protect against corrosion. I have found a dielectric grease but think that could get messy plugging and unplugging often.
2. Do you treat the Navionics card in the same manner? Spray for corrosion protection?
Thanks in advance.

I keep a can of WD40 in my front hatch. I spray the connectors when I unplug it to displace any water that might have gotten in it. There might be a better product, this is just what I use. I have a Lowrance also. I noticed they get rust and corrosion easily in salt if you dont take care of them.

Dielectric grease is highly recommended on any type of connection that you use for your electronics except for those that are protected by a gasket-lined cover, such as a memory card.  So don't use it on the memory card, but use it on any other piece of exposed connector metal.

+1 on the dielectric grease. I have Elite-4s on both my boats. I also grease and cap the unused port on the back of the unit and run a thin bead of silicone RTV around the micro SD card access flapper door. I've completely submerged these units on several Hulis and have had zero issues. 

Thanks for the helpful info guys!
Just returned from Ace with a can of dialectric grease. Having difficulty finding a vacuum nipple cap of the right size. I'll keep trying.
Thanks again