Hi there Hitman
I painted it all over again , and it looks better now , I gonna take picture of it when I'm finished with it
Regarding airbrushing , it's really easy I'll explain it to you .
What I did , I airbrushed the lightest colour first all over the sub , and when the paint is dry , I mask a line hull/waterline and airbrushed with very low airpressure in all the corners and used the paint as fillers in crack and so on , and I airbrushed many coats on the darkest colour
And at last I airbrushed " Testors Dullcoat "
all over the sub ( three coats ) so no I am gonna weathering the sub , remember it's a very old kit from 1976
So I build it straight from the box
The deck I hand brushed with a mixture of 60% 112 Humbrol + 40% 160 Humbrol with a little of grey and rust , and finally I airbrushed the waterline as you suggested (The tanks ) with nr 67 humbrol . So the sub looks really different from the picture above