Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_name_47 ( year_built INTEGER, last_refurbished INTEGER )

### Question ###
What is the earliest year built for the ship refurbished earlier than 2013?

### Accurate SQL ###

SELECT MIN(year_built) FROM table_name_47 WHERE last_refurbished < 2013