OP-204 patrol boat 1:100

[Michael Mash]

Card modeling is nothing like plastic.
Many modelers build “waterline” projects before attempting a full hull.
From personal experience: my first two ships were full hull, but I built the lower hulls with balsa, and sanded them to shape. I didn’t build a successful full hull till my third ship.
If you enjoy experimentation, keep trying techniques until you are happy with the appearance.