New holes were cut in the boat to place the thruster at the very bottom and front of the original hull. I happened upon a 22mm hole cutter in my tools so used this to cut the new holes, but with its coarse teeth and the rake of the plating it caused some damage to the outer plates I'd added by pulling them away from the structure a bit. Nothing serious, but a bit more remedial work was needed.

Then, with a bit of wiggling and filing the thruster was fitted into its new position and thoroughly sealed and fixed with epoxy. The old holes were rough blanked inside.