When your electronics are connected, there’s usually no issue. The screw connections on the back of the depthfinder or GPS are designed to be watertight. But what about the times you leave the powered gear home and go it by instinct alone? The solution is simple: dielectric grease, and rubber caps that are designed to protect the protruding end of a nut and bolt.
The result is a water-tight protected cable plug. You should still be careful to keep it from getting into sand or other debris. The grease is sticky, and adding grit can make a pretty big mess.
You can find these screw protectors at your local hardware store. They come in different sizes, so measure the cable end you would like to protect prior to purchasing.
Adding a small dab of dielectric grease on the contacts of the female plug, then placing the cap over it, adds even more protection. This tip should prevent corrosion and extend the life of your electronics cables.