I painted the entire boat with brass first after priming with a black primer. To weather the boat I went about then airbrushing the model with RUST(Model Master), Then I mixed a brown/green combination using Tamiya...And sprayed,drybrushed and sprayed it again. I didn't pre shade the model because it looks like...preshading.
I then went about weathering it more Drybrushing and Air brushing. Using a light green, I went about the boat to create the Patina. It's easy to go over the top on this so you need to discipline yourself to stop when it's there. Don't over do it...