try http://www.isle-of-man.com/manxnotebook/famhist/genealgy/emig.htm for some background; Smuggling was a major manx industry from c. 1680 to 1765 (and possibly later) but directed against English + Scottish customs.
The 'white slaves' may have been the indentured labour scheme on early 18th century.

Costain name comes from South of Island.