Day after day, day after day,
We suck, nor breath, nor motion,
As idle as a painted ship,
Upon a painted Ocean.
I think this is a metaphor that is trying to say the sea and the ship are still. In a painting there are still waves, but the author who wrote this stanza -Taylor Coleridge- is trying to say that the water of which they were sailing on was still like a painting but still had a few waves.