This is if you encounter a an alpha raptor near the shore. The best option I've found is to use a longneck rifle with a scope. Dump all your things into a raft with a chest, once you're stripped attract the alpha raptor to the edge of the shore and let it kill you.Respawn on or near your raft with all your things and take it out to the raptor but maintain a far enough distance that it doesn't chase after you. from there croutch so you get a steady shot and use the longneck and scope to shoot at it. It depends on the level but I managed to take out a level 10 with this strategy. Make SURE YOU HAVE LOTS OF AMMO. Good luck friends.
If One is following you and you are not prepaired hide behind a larhe herbivore like a trike. The raptor will accidently hit it and they will fight to the death. Run while the battle is still hapening. Hope this helped. Up for noobs who have never seen a raptor