#Put the numbers down and walk away with your hands up
Put the numbers down and walk away with your hands up
You've gone too far down the rabbit hole, none of this will really help you.
What's going to help is knowing that they're using magic wood on their hull. With normal wood the cannon become effective when you can make out the uniforms of the officers on board with the naked eye. With magic wood the cannon only become effective when you can also see their ranks.
Don't give fixed numbers, especially not muzzle velocity and material strengths. These require a significant technological base to measure and understand. Give human values, distances at which you can see something, like the whites of their eyes (accurate musket range). Your cannon will work, you define them as working, all you have to do is give the range at which they become effective in an emotive way.