Like a blind person you develop whatever senses you have left.
In the 70's I got to know many of the old BC captains thru my friendship with the Dolmage family
They told me that in the days of steam tugs they would feel thier way up Coal Harbour in the fog
by listening to the changes in the echoes.
As you know that is a deep harbour so depth
soundings did not work so well, but they could slowly head
right up into Indian Arm by DR and steam whistle sound.
Also taught me the Fog
trick of slowing down to a drift in the narrows and let the main stream carry you safely thru the pass.