In 2019 various challenges will be set for boats built on a hull to the shape and size of the standard Springer tug models (18 x 8 inches). There is no restriction on the power or number of motors.
There will be several events and different challenges so the only guidance is to build a robust boat that is reasonably powerful. It will be wise to fit the two pusher uprights at the front.
There will also be a prize for the most imaginative / inventive appearance.......
There are plans available on the net, but be aware that you might need to rescale them to get them printed at the right size. Alternatively, the dimensions below can be used to get the shape.