What is griefing
I see a lot of posts here that are just bad experiences with other players, usually getting sunk or shot without them seeing any reason for it or beating a skull fort and then getting your loot stolen. While I do symphatize with people that had that back luck, this is in not griefing but just PvP.
Griefing is continuous spawnkilling, brig abuse and other acts that deliberately ruin the gameplay of players which they usually cannot resolve themselves. Everyone probably experienced at least some of it and stories about your sad PvP expierences give some form of relief, but that won't really solve the issue.
Prevent splitting up PvE and PvP
Let me start by saying that I think seperation of groups on special servers is something I'm against because there are better and easier way to solve this without spending time breaking out game mechanics and turning the game into something completely different. The time spent on breaking up the game would be much better spent invested in the game as a whole on new features everyone could enjoy.
Here are some suggestions against griefing and general PvP frustration. These are not all my ideas, I've seen several around the forums as there are enough people that think in non game breaking solutions that would benefit the entire community instead of just a specific group.
Suggestion 1: Improved matchmaking / searching the seas (PvE/PvP balance improvement and get griefers to annoy eachother)
Instead of creating seperate servers that require complete rework of the game's core mechanics, I think it would be a better idea to try and make sure that people that kill a lot of others and sink a lot of ships end up dealing with people that are into the same.
To do this I think Rare should calculate a number to each player based on the amount of player kills / ship sinking / deaths / voyages completed and when matchmaking take the average of everyone on the ship to add them into a server that has around the same number. It doesn't have to be the exact same but I think they could create several steps or leagues of server slots. This doesn't have to be surfaced to the players.
The result would be that everyone on the server is about as experienced as the others and usually have a somewhat similar way of playing. This way pure PvE players would be matched with more like minded players, but at the same time it would put all the griefers and kill on sight people together with others that enjoy that type of gameplay and most importantly away from the rest. This also at the same time allows PvE players dip their toes into a more fair PvP setting with equally experiences people.
I think this solution would benefit the entire community without changing the game's core mechanics to cater to specific people. It will allow everyone to play the way they want without removing the 'danger' of other pirates.
Suggestion 2: Private crew / invite only crew (Rare is already working on this one)
This one has been suggested a lot and Rare is already working on it as far as I know. Having a invite only crew will definitely reduce the amount of brig abuse, the sooner this can be implemented the better.
Suggestion 3: Don't move victims, move the guilty
I would like to see the people commiting the 'crime' to be punished, not the people being victim to it. Keep a counter that counts up each time someone gets killed on his or her ship within a minute of spawning by a certain crew. Once the counter hits 5 the griefers ship and crew get transferred to another server and make sure to show them the reason why they get moved: "Ruin other pirates experiences as you please and you will be surprised by different seas".
This could even result in a auto ban after being moved a certain number of times.
Suggestion 4: Name and shame, but keep it ingame
Whenever someone has multiple offenses of griefing they'll probably be removed from the community with a ban or something. Before that however we could basically show everyone that certain people have spent time griefing other players. Make them walk around with a title of shame, a unchangeble goofy outfit or pink dress, a sign around their neck, something that punishes them for not respecting honor among thieves and showing others that it might not be someone you want to play with. Hopefully making them change their ways, but also warning others.
Suggestion 5: Removing players from your crew
While private crews will prevent brig abuse, playing with random people is still a great way to meet new people. If you encounter someone who does spent time acting like an a*s to your crew or (to pull it into this topic) seems to enjoy the act of griefing others, it should be able to remove this person from your crew.
Suggestion 6: Have Rare report back about what's being done with griefers/cheaters
I understand that Rare can't give full details on all their internal actions, but maybe as a comfort to some and a warning to others Rare could give an update every now and then about their actions against griefers and/or cheaters.
A general message that for example something along the lines of:
"We've heard your concerns and received a lot of reports about griefers, hacks or cheats. As said before we have a zero tolerance policy on these matters and want everyone to be able to enjoy the game without encountering these kinds of behaviours. So since the release of the game we issued 12,457 warnings to players about griefing, gave 7521 players a temporary ban for repeated griefing offenses and banned 2501 accounts for cheating/hacking. We will continue the fight against behavior that only has the intent of ruining other peoples experience. Thank you for your patience and understanding, we hope to see you all on the seas!
Other PvP suggestions
There were some other suggestions to improve PvP aspects like flags to indicate your intention or a bounty system to reward players for going after the ones that murder/sink a lot of others but that's not really related to griefing, so I'll skip that for now.
That's all folks
That's all suggestions against griefing I could think of, let me know what you think or share some other suggestions that help us grow this community into something greater.