It looks good so far Serhan, but I think you need more shading and highlighting. The shadow under the rolled edge of the conning tower implies a more-or-less zenithal lighting, but there are no shadows cast by the crew members' bodies on themselves or the deck. Look at the original photo to get an idea. The sea and sky seem monochromatic and could use some enhancement - light blue at the bottom of the sky going darker as the eye goes to the top, while the sea could use some variation in the blue tones to denote wave action and some 'sparkle' caused by the sun glinting off the surface.
Cheers,
Glen