Time for action — giving the hull a hull shape
You've got the top view of the hull in good shape. Now it's time to work on the shape as seen from the side:
Press Numpad 1 to get the Front view.
Notice that the hull is still oval shaped, as seen in the following screenshot on the left. Check that all the control points are level vertically. If any control points are higher or lower than they should be, you can select them and scale them in Z, or move the vertices in Z.
Press Ctrl+R to activate the Loop Cut tool. Select the horizontal magenta line.
Move the orange line until it is almost all the way up to the top of the control object as seen in the following screenshot on the right. This will control how tall and curved the deck is. There is an Edge Slide readout in the 3D View header. Move it till the Edge Slide is about -0.85. Use the Shift and Ctrl keys to give you better control when sliding.
Press Numpad 3 to get the Side view and you can see the effect these new control points have all...