If these are indeed your first SB drawings, then it's an outstanding job, well done.
Now I believe you should work on the shading of the underwaterhull, and minor things like lining up the name and credits on the right top corner.
Been here lurking for years until i decided to create my own account and designs. Uhm any tips on how to improve underwater shading, I have troubles on that. Thanks for helping i really appreciate it!