The shading around the secondary guns seems too dark, and it looks like you've used two-toned shading on the bridge.
The blue shade you've used on the anchor seems a bit odd. Not wrong per ce, I've just never seen anyone with blue anchors, not even ships with a blue camo pattern.
I'm not familiar with when the design is from, but since it's a pre-dread, some gold filigree around the bow and stern probably wouldn't be out of place.
The fighting tops are in all probability full platforms, so you shouldn't be able to see the mast were it passes through them.
about the shading you are right, it will be removed, but as this is still a WIP and I'm experimenting with the colours.... that's also where the blue anchor comes from
and thanks for the tip on the gold on the bow and stern.