Towing Barge
I see you live in or near E.Port so I suggest you visit the Boat Museum as they have a host of barges on display which should give you inspiration for your model. I have three, two based on the Mobile Marine F/glass hulls and one built from a MMI plan from ply. Look realistic when towed with a tug and used to see similar on the Mersey many years ago. For ballast I use milk bottles that I fill with water at the pondside and place in the model at the lakeside. Much easier than carrying heavy lead in the model.
dave976