Waiting for the ferry

Text 1: Crossing the estuary, by Louisa Penhallow

An original letter written in a nineteenth-century voice; a period simulation, not an archival document.

Dearest Kate, the ferry across the estuary runs only when the tide allows, and so we sat two hours in the parlour of the inn before the boatman would take us. He explained that at low water the far landing stands above a broad bank of mud, and that no passenger can step ashore there without sinking to the knee. Two gentlemen from the coach offered him double the fare to go at once; he refused them both and went on mending his net. When at last the water crept up the slipway he called us down, and we crossed so smoothly that Mamma declared the wait had been worth every minute.

Explain why the boatman would not take the passengers across earlier.