Warning - ruleset change.
Friendly fire for pirates was initially allowed to provide the opportunity for group vs group fights. OW was always pulling all the pirates to one side in the instance (even reinforcements) and as a result 6 v 6 were always 11 v 1 in the instance.
Many pirates started to use this mechanic always joining the friendly side to sink the opponent. No group fights were happening.. only abuse. We have to change the rules as a result.
Consensual green on green damage, especially to deny a resource to the enemy, or, for example, asking a friendly to ram between you and an enemy locked in boarding action to prevent you from losing, is ok. Nonconsensual green on green is not ok.
Bear in mind that consensual or not, doing too much green damage will cause you to run afoul of the automated systems, so use consensual green on green damage frugally.