The rhyme is chu/ch’u/ku/ru/su; tones match, and there is parallel expression in the second and third couplets.
There are some problems of interpretation. Many of the commentators seem to think that the cowherd and fisherman are wearing the rainhat.
The tousle-headed cowherd, lightly rainhat clad, tends his calf;
the old fisherman shows his true self when rainhatted he follows the gulls on the sand.
It is hard to see that the characters warrant this interpretation. To think of the boy and the old man as typical of those who do not worry about formal dress seems the preferable interpretation. The final phrase in the third couplet could also be translated as “I climb Moon View Terrace.”
My airy rainhat is an empty boat;
worn once it’s mine for forty autumns.
The tousle-headed cowherd, lightly clad, tends his calf;
the old fisherman shows his true self when he follows
the gulls on the sand.
Drunk, I doff my hat and admire the flower trees.
When the mood comes, hat in hand, I climb the terrace
to view the moon.
For worldlings, formal dress is a matter of looking right.
Me? I haven’t a worry, not even when wind and rain fill the sky.