I'm certainly no expert, but...
We mounted our flat screen teevee on an articulating arm so we can change the viewing position as desired.
Next, I screwed a brass eye bolt (about 3/4 inch eye diameter) located a few inches above the mounting base, on the bulkhead.
When we get underway, we simply loop a short bungee cord around the top portion of the tv, which holds the unit securely against the bulkhead.
Arrrr Boy can even watch his favorite Popeye cartoons while we're plowing through waves if we position the shock cord above the screen area.
Now - the dedicated bungee simply "lives" with both hooks in the eye bolt, behind the television, always at the ready. All we have to do is loop it over the top.
AND - the eye bolt makes a primo place to help secure and organize all of the countless cables & wires leading to & from the teevee and input devices with just a bit of string.