feat: AR-Shipdesign initial commit

arshipdesign/parametric/series60.py

@@ -22,6 +22,19 @@ from arshipdesign.core.hull import Hull
 from arshipdesign.core.offsets import OffsetsTable
 
 
+def _standard_sheer_z(
+    x_sta: np.ndarray, lpp: float, depth: float,
+    fwd_rise_frac: float = 0.04, aft_rise_frac: float = 0.020,
+) -> np.ndarray:
+    """Línea de cubierta parabólica: mínimo en cuaderna maestra, sube hacia proa/popa."""
+    xi = x_sta / lpp   # 0=AP, 1=FP, 0.5=midship
+    return np.where(
+        xi >= 0.5,
+        depth * (1.0 + fwd_rise_frac * ((xi - 0.5) / 0.5) ** 2),
+        depth * (1.0 + aft_rise_frac  * ((0.5 - xi) / 0.5) ** 2),
+    )
+
+
 def make_merchant_hull(
     name: str = "Buque Mercante / Supply",
     lpp: float = 20.0,
@@ -49,9 +62,10 @@ def make_merchant_hull(
     flat_bottom_frac : float
         Ancho del fondo plano / manga (0.85–0.94).
     """
-    x_sta = np.linspace(0.0, lpp, n_stations)
-    z_wl  = np.linspace(0.0, draft, n_waterlines)
-    xi    = (x_sta / lpp - 0.5) * 2.0
+    x_sta   = np.linspace(0.0, lpp, n_stations)
+    sheer_z = _standard_sheer_z(x_sta, lpp, depth, fwd_rise_frac=0.04, aft_rise_frac=0.020)
+    z_wl    = np.linspace(0.0, float(sheer_z.max()), n_waterlines)
+    xi      = (x_sta / lpp - 0.5) * 2.0
 
     lcb_shift = 2.0 * (lcb_frac - 0.5)
     f_plan = _merchant_plan_form(xi, cb, lcb_shift)
@@ -91,7 +105,8 @@ def make_merchant_hull(
         lpp=lpp, beam=beam, draft=draft,
     )
     return Hull(
-        name=name, lpp=lpp, beam=beam, depth=depth, draft=draft, offsets=offsets
+        name=name, lpp=lpp, beam=beam, depth=depth, draft=draft,
+        offsets=offsets, sheer_z=sheer_z,
     )