Cute little thing.
A few points:
I would drop the dark grey out from the deck-edge, or lower it by two pixel (leaving one "white" between the black edge)
The funnel is currently Pitch black, Color it rather with really dark grey instead (and use a notch ligther shade to give it the round affect on shading)
There are some odd darg-grey pixels (proparly a file-transfer errors) in the rudder
The war-ensign is propably bit out of place despite the "war like" name
I would make the portholes in the bow two four pixel wide but retain the three pixel heigth, that way they actually look little bit better as round objects
Also, i would draw the Lines in the hull with two pixels so that place one line with one notch ligther than the hull color above and another line bit darker bellow.
In the deckhouse, It could look better when the railing color abrest the brown surfaces would be also brown (make them two notch darker than the brown you use on the walls). Also, a bit of shaddowing bellow the roof would crown the thing, there I suggest simple two lines of the one notch darker shade from the brown used on the walls (and perhaps make similar adjustment from the window color to add with the shaddow)