<|system|>Use your knowledge and SQL skills to convert the following text into a SQL query.
Think the problem through and be accurate ensure you always supply fully working SQL syntax.

SQL Statments should be wrapped in <codestart type="sql"> and </codeend> tags.

Example output:
<codestart type="sql">SELECT * FROM table_name;</codeend>
<codestart type="sql">SELECT column_name FROM table_name WHERE column_name = 'value';</codeend><|end|><|user|>what is the sum of tonnage when the type of ship is twin screw ro-ro motorship and the date entered service is 11 february 1983?

SQL Table Create Statement:
CREATE TABLE table_name_73 (tonnage INTEGER, type_of_ship VARCHAR, date_entered_service VARCHAR)<|end|><|assistant|><codestart type="sql">SELECT SUM(tonnage) FROM table_name_73 WHERE type_of_ship = "twin screw ro-ro motorship" AND date_entered_service = "11 february 1983"</codeend><|end|>