Having a couple of tugs in my fleet. I always considered building a dumb barge to play with. However i was always concerned about the weight required for ballast, etc.
However june 2019 model boats mag has come to the rescue.
The hull design allows has a flooding ballast compartment. Thus reducing the need for lots of ballast.
Construction is straight forward. I used scrap packing case plywood and any wood i had lying around.
Another feature was an exchangeable cargo section allowing cargoes to be changed with ease.