T Shirt design

I need a drawing for a t-shirt. I have a concept, but need to turn it into a printable design. One photo attached here shows a mermaid in the water looking at a sailboat departing. That is basically what I want, except that I want the boat to be a ferry (it's in the other picture attached here). And the whole thing should be suitable for a t-shirt, so doesn't have to be completely detail oriented