Genevieve's eye analyzes the stick, then she nods.
Champing on the fuse, she spits the extra onto the deck. Then she lights the stick from her lantern's flame. It sputters, and she watches it closely, making sure the fuse timing is right...
"Jon. 12 Seconds! No more!"
She hurls it into the hold, then quick-draws her cockatrice gun, waiting...
SpoilerI cut the fuse to 3 rounds. It'll take at least one round for Jon to get clear.