Chart Plotter: physical installation
There are many mounting options for chart plotters, some of which have fancy swiveling armatures which allow the device to be swung out of the way when not in use. My diminutive cockpit is not well suited to such solutions, and in any case they are expensive options.
Two possibilities seem suitable. One is to mount the device on a companionway board that slides into the companionway, but this makes access to the cabin problematic. I also have a compass so mounted, and while I use it only rarely, a long trip in unfamiliar waters mitigates in favor of its use.
The second option is to take advantage of the port-light in the cabin bulkhead. I fashioned a wooden plug, (4 7/8" diameter x 1 5/8" depth) that is sandwiched between two discs slightly larger than plug and the rim of the portlight. The plug is thus captured securely in the port-light housing (hanger-bolts and wingnuts), and the swivel base of the chart plotter attaches to the plug. The cabling will pass through the plug as well, and the chart plotter will be easily removable to secure it inside when not in use. My reservation about this configuration is that the chart plotter will be somewhat vulnerable to being stepped on, being in a relatively high traffic area for boarding. The installation is fully reversible, however, so if it seems not to be working out, I can remove it without trace.
I used the same idea to make a foam water-proof pass through for the shore power cord that fits snugly into any of the portlights so that rain can be kept out with the power cord deployed.