Maybe have the exhaust shooting out from an external sourced rocket engine or even an engine from a fighter jet. Perhaps you could mask off the boat's engine to resemble one. Also the windows of the cockpit are blue and the sky is black in your Chop. That's an easy fix. Just "mask out" the blue parts of the windows. Then in your "Mask Properties", lower the "Density" a bit to allow some of the winnow to show through. You may or may not have to mess with a Hue/Sat adjustment to darken the Blue color of the windows. This way it will look like there is some glass in the cockpit, but it will be see-through and you will see the black sky behind it. The bottom of the boat is white. You may want to color it orange so the rocket color looks more consistent.

Thank you for fixing this

Author, please link all sources to the page that shows the copyright and usage information, not the download pages.

As I thought, source 3 is a render, and not useable. When using DA for source material, always use this link, which will take you to the stock section. http://www.deviantart.com/browse/all/resources/stockart/ Even then, some images will be renders or premade backgrounds, which are not valid sources. You have plenty of time to find a useable background and revise your entry.

Please fix links 2 and 3. They don't lead to images. The background looks like an illustration and wouldn't be useable in any case.