When the Pilgrims left England on August 5th, 1620, there were 90 passengers on the Mayflower, and 30 on the Speedwell.
The intention was that the Speedwell would permanently stay with the Pilgrims in the new colony, so that they could use it to explore the area, for fishing voyages, transportation, etc. The Mayflower was not going to stay in America.
Very early in the voyage the Speedwell began to leak and they realized it was not properly suited for open ocean travel. It's captain (Reynolds) was worried that the ship would not make it to the New World.
This led to a delay in travel, over a month, and would lead to arriving in the New World at a difficult time (winter). Also, without the Speedwell, the Mayflower will be way overcrowded. Here is Captain Reynolds' perspective:
DECISION: You are a passenger on the Mayflower. You have been told that the Speedwell is going back to England. You can go back with it, or you can go it solo with the Mayflower. But if you go on the Mayflower, you will be stranded in America after it drops you off. What do you do and why?
Click Here after you made your decision to see what the pilgrims chose.