“The gorge is narrow, only broad enough for three ships to pass abreast, so it is not possible to directly fire upon the Sea Gate with cannon. However, we have devised a scheme to fire a bomb from the prior stretch of the gorge, over the intervening rock wall and into the top of the gate.

“Once past the gate, there is a harbour pool capacious enough to host a dozen vessels of a similar size to your Sea-Cat, with three timber wharves built out from a paved quay. The treasure- and store-houses of the Scholar-Pirates are built on an inclined crescent above the quay, along with residences and other buildings of no great note.”

“You are an unusual puppet,” said Fury. She took the wineskin and poured another long stream down her throat. “Go on.”

Fitz nodded, and returned to his first sketch, his finger tracing a winding path between the islands.

“To get to the Cror Holt entry in the first place, we must pick our way through the so-called Secret Channels. There are close to two hundred islands and reefs arrayed around the central isle, and the only passage through is twisty indeed. Adding complication to difficulty, we must pass these channels at night, a night with a clear sky, for we have only the dark rutter to guide us through the channels, and the path contained therein is detailed by star sights and soundings.

“We will also have to contend with most difficult tides. This is particularly so in the final approach to the Sea-Gate, where the shape of the reefs and islands—and I suspect some sorcerous tinkering—funnel two opposing tidewashes into each other. The resultant eagre, or bore as some call it, enters the mouth of the gorge an hour before high water and the backwash returns some fifteen minutes later. The initial wave is taller than your top-masts and very swift, and will destroy any craft caught in the gorge.

“Furthermore, we must also be in the Cror Holt gorge just before the turn of the tide, in order to secure the bomb vessel ready for firing during the slack water. With only one shot, He . . . Martin, that is, will need the most stable platform possible. I have observed the slack water as lasting twenty-three minutes and we must have the bomb vessel ready to fire.