Blackout is when complete failure of electrical power brings the ship to a standstill. If the crew is not prepared to act quickly and efficiently, the consequences can be fatal.
In most cases loss of electrical power also leads to a loss of propulsion which can cause contact, collision or grounding. The further consequences of this can be injuries or fatalities, pollution, or disruption to cargo schedules.
As a result, there can be substantial claims and further costs. These can be anything from hundreds to thousands of dollars.
With a fully prepared crew, it is more likely that the consequences will be greatly reduced.