You will probably get the sail soon after getting your purifier and grill. The sail can take a bit of waiting and hooking barrels in order to get the 3 scrap required to craft it but it shouldn't take too long. Along with 3 scrap, the sail also requires 20 leaves and 10 planks. Once you have the sail placed you can start controlling your raft to be in favor with the wind in order to move more quickly and steer towards islands.
The stationary anchor will take longer because it requires 3 metal ingots and 1 hinge. You could find these from crates on abandoned rafts or underwater at islands but it is more likely that you will have to mine metal ore at small islands and smelt the metal in a smelter. Once you have placed both a sail and a stationary anchor on the same raft, you will get the achievement.