Just a thought about batteries; If you can, arrange your electronics (flashlight, radio, cell phone emergency charger, etc.) so they all run off of the same 1 or 2 sizes of batteries. It cuts down on the cost and bulk of the spares since you're not buying different types for each device.

Also, consider water purification tablets. Though they're more suited to airtravel and utilities problems then cruise ships.
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Hope for the best and prepare for the worst.

The object in life is not to be on the side of the majority, but to escape finding oneself in the ranks of the insane