This is the top of a Lister. Many fishing boats used them to generate electricity. Click this text to see the Lister Wikipedia page which describes their uses Many fishermen use the term Lister for any brand generator. Interestingly enough the head quaters and Manufacturing facility for Lister are in Dursley, Gloucestershire in the UK.
Beautiful Industry- Essex Shipbuilding Museum Lister, originally uploaded by captjoe06.
Good Morning Gloucester 