I found using technique angle connectors with technique bricks gives a nice round shape and the ability to increase/decrease the width with little problems. Small 1 stud or 2 stud wide plates over the top with tiles on top give a nice finished look. I'm having very good success using this for my Schnellboot as well.
This is a posting of the well known Custeau exploration vessel the Calypso, made by Henrik Hoexbroe.
A wonderful example of how these two techniques can work together to make a very convincing hull structure. Permalink