Complex sentence: The fleet also includes a barge, used for dredging at Gills in the summer and an extension to The Hope pier in the winter, a former fishing boat, to tow the barge and a tug/workboat for general duties.
Split into simpler sentences: The fleet also includes a barge used for dredging at Gills in the summer and an extension to the pier at The Hope in the winter. Also an ex fishing boat to tow the barge and a tug/workboat for general duties.