No, they didn't. Columbus thought he could find a fast route to Asia because he grossly underestimated the circumference of the Earth. Spain was advised of thi

No, they didn't. Columbus thought he could find a fast route to Asia because he grossly underestimated the circumference of the Earth. Spain was advised of this (the more correct circumference derived by Eratosthenes was commonly known), and only funded Columbus on the off chance that if he might stumble across something of value, they would rather that belong to Spain than a rival power. It was a cheap gamble for Spain at the time.