Not bad at all.
I can't comment on the accuracy of the drawings, but there are a few formal points that can be improved:
- The shading of the stacks and other cylindrical parts is too photographic for the SB style, and clash with the rest of the drawing. The accepted standard is three levels of brightness around a half-cylinder for the same base hue.
- The shading of the bottom hull around the rudder is a nice effort for a fairly complex shape, but is also on the rich side and doesn't match the rest of the hull.
- In the original version, the top of the foremast should have no 2-pixel black segments. Stick either to 1 black line or 3 with a filler color.
- Some of the cables in the rigging of the original version don't fit together very well.
- The foot of the bow mast has disappeared behind the railing, in all versions.
- All versions except the first have leftover pixels from the original foremast hanging in the air.
If that's all there is to correct on your drawing, then good job!
I'll try to fix some points. They are not final designs. Thank you for the remarks.