What does haven's dumb mean?

Answer 1

This is a line from a poem:
Heaven-Haven
by Gerard Manley Hopkins

I have desired to go
Where springs not fail,
To fields where flies no sharp and sided hail,
And a few lilies blow.

And I have asked to be
Where no storms come,
Where the green swell is in the havens dumb,
And out of the swing of the sea.

The line to which you are referring says that the author wishes to go to a haven or sanctuary where the green swell of the ocean is dumb, or silent - in other words, he wants to go to a nice port somewhere without great storm waves beating down.