Pirates are one of the negative expedition outcomes. Their default event weight is 20, which equals about 17.86% with the built-in total weight of 112.
How does this expedition outcome work?
Under the default configuration, encounter intensity is roughly 30–80%. Final losses for each ship type are then clamped to approximately 10–95% of the number sent.
What are the default parameters?
Losses are calculated from the fleet that was actually sent, so a larger expedition increases not only the potential of some rewards but also the exposure to a damaging result.
What determines the result?
A pirate encounter does not automatically destroy the entire fleet. The risk is still substantial enough that you should avoid sending a composition whose partial loss would cripple further account progress.
How should you use this in practice?
Negative expedition outcomes are drawn from the same event system as rewards. Sending a larger fleet can improve the potential of some rewards, but it also puts more units at risk when a damaging event occurs.
What should you watch out for?
An expedition should therefore balance potential reward against exposure. Do not send ships whose loss would cripple your account solely to maximize one reward parameter.
Related FAQ: How does a black hole work on an expedition? · Does expedition reward use ship value or ship count?