Scrapping is like a freight boat

When I was around 12 I was at sea gate beach Brooklyn NY (my grand dad lived there)
I was with my Brother in Law and we saw a freight boat , He said probably on it's way to China , I said but how fast can they go
he said 20 Knots

Knots I asked ?? around 22 to 23 mph I said thats slow
He said not really see 24 hours a day the boat travels and they take routs that are direct .

Lately I see scrapping is like a freight boat not so fast but constant day in day out it's a power house way to earn
and acquire money .