Water ballasting is the feature Macgregor owners keep coming back to. It's what lets the boat be trailed by road one day, then sailed or used as a river or canal boat the next.
The Macgregor Owners Association of UK will be showing boats on Marina Walkway 3, giving visitors a chance to see how the system works.
The association describes itself as friendly, and says it supports members to get the most out of their boats.
Details on the association and its boats are at macgregorowners.org.uk.
