.. I recommend a chart-plotter. They are weather proof and pretty hardened for sailing....
Sailing solo and coming to a unknown shore, try to plot a course to a nearby marina, while struggling with the boat on bad seas and high winds, with water flying all around.
That's when you are going to need it most.
No way, a PC is a back up tool unless you have a crew with a guy inside doing the navigation and even so you should have a back up Pc because they tend to be very fragile machines on muscular and humid conditions.