In an example of foreshadowing, Maurya warns Bartley not to take their family’s rope to tie up his horses for their journey to the sea:
You’d do right to leave that rope, Bartley, hanging by the boards. It will be wanting in this place, I’m telling you, if Michael is washed up to-morrow morning, or the next morning, or any morning in the week, for it’s a deep grave we’ll make him by the grace of God.
This is an example of foreshadowing in a couple different ways. First, as Maurya notes, the rope is currently sitting with the white boards, as she’s planning to use the boards to make Michael's casket and use the rope to lower it into the grave. Her statement that Bartley should leave the rope foreshadows the fact that Maurya will come to learn that her son Michael has died shortly after this scene.
This moment also foreshadows Bartley’s own death. While Maurya is stating that she wants him to leave the rope for Michael’s sake, she will actually end up using the rope to lower Bartley's coffin into his own "deep grave" after learning that Michael's remains were found on the coast of mainland Ireland and she will not need to bury him after all.
When describing the staging at the beginning of the play, Synge writes, “Cottage kitchen, with nets, oil-skins, spinning wheel, some new boards standing by the wall, etc.” It becomes clear over the course of the play that the “new boards” mentioned here are ones Maurya preemptively purchased for Michael’s coffin. In this way, the boards’ presence from the very first scene foreshadows both Michael’s and Bartley’s untimely deaths.
The meaning of the boards is established a couple pages into the play when Maurya tells Bartley the following:
It’s a hard thing they’ll be saying below if the body is washed up and there’s no man in it to make the coffin, and I after giving a big price for the finest white boards you’d find in Connemara.
It is clear from this passage that Maurya acquired the boards in order to build a casket for Michael in case he has died at sea (which she does not yet know to be the case). The boards stay up against the wall through all of her worrying over both Michael and Bartley, a looming presence that suggests she cannot avoid the fate of losing at least one of her sons. By the end of the play, upon hearing that Michael’s body was found on mainland Ireland, Maurya ultimately decides that she will use the boards to build a coffin for Bartley instead, accepting both of their fates in the process.
