i too am working on my first ship,but what i did was took one drop of testors brownand one drop of rust mixed with about 15 drops of thinner mix that and put it on with a brush,then take a dry brush and tap it,this makes the rust effect.then i took a pencil and rubbed some lead on different spaces then took my finger and pulled the lead downwards to make the muck,i think it turned out alright you can see the pics if you scrool down to enterprise weathering begun,i hope this helps
Actually, the best armor modeler I know woke me up early one Saturday morning after he had finished painting and weathering a ship model for a group project. “Weathering a ship is just like weathering a tank, except you leave off the mud”, he said.
Think of it like a tank. Everything is painted gray. Apply an overall wash of darker gray to settle into the recesses and make shadows. Then go over with a drybrushing of base color (perhaps lightened just a hair) to pop the details.
I use Paynes Gray oils to make my gray washes. I’ve also used a deep purple on some of the USN purple-blue based schemes. Then a drybrushing of the original color.
Unless you are going a craft which received a lot of wear and didn’t get a lot of hull upkeep (i.e. a Flower corvette or similar) - go lightly on the running rust on the hull. Superstructures were maintainable underway - so they didn’t show rust. Some light rust-colored Prismacolor touches along scuppers and logical flow lines on the hull as well as some on the hawse hole are usually more than sufficient.
Oh, for all of you who are doing a PT boat. They were made of wood and wood doesn’t rust. It may be right to show a bit of rust along steel fittings but if you see a PT with running rust on the hull that modeler needs to be taken aside and have a good talking to!