Sunset and evening star,
And one clear call for me!
And may there be no moaning of the bar,
When I put out to sea,
But such a tide as moving seems asleep,
Too full for sound and foam,
When that which drew from out the boundless deep
Turns again home.
Twilight and evening bell,
And after that the dark!
And may there be no sadness of farewell,
When I embark;
For tho’ from out our bourne of Time and Place
The flood may bear me far,
I hope to see my Pilot face to face
When I have crost the bar.
By Alfred Lord Alfred Tennyson
The bar referred to is a sandspit or similar promontory at the mouth of a river or harbour where tides have deposited sand over time. To hear the wind and waves moaning off the bar usually means that there is insufficient water to sail over the bar without grounding. Hence the second verse and its reference to a “full tide” or “high water”
Reproduced from here