On a recent cruise on the Crown Princess, I had issues with the outlets and I am planning a different approach for my upcoming cruise. I had brought a plug-in "outlet extender" but it covered the light switch when plugged into the outlet. The hairdryer was also plugged in so we were continuously switching out devices! I had heard "power strips" were not allowed.
{I am referring to the outlet on the desk/refrigerator/built-in hairdryer location}
Most of my devices are USB charging so I bought a multiple USB strip that will charge 7 devices at once (E-cig, cell phone, ipad etc.) and has on/off switches for the ports - It plugs into my USB/Outlet converter into one plug and it works so well I have begun using it at home. Bonus - it was only 12 bucks and is smaller than a curling iron!
NOTE: ALL USB STRIPS ARE NOT CREATED EQUAL SO BE SURE TO READ CAPACITY AND DEVICES SUPPORTED.