You need some sort of fuse.
What's a fuse made out of?
Rope.
There's some rope in the hold.
Use the rope with the cannon.
Lighting the cannon requires something else, though.
Like fire.
You have to bring fire to the fuse.
If only you had a match.
But anything flammable will work.
Use Stan's business card, the cereal box, or a T-shirt with the fire in the kitchen.
Use the flaming mass on the fuse.