diff --git a/data/config.ini b/data/config.ini
index 6fd5983..b9b2d50 100644
--- a/data/config.ini
+++ b/data/config.ini
@@ -8,6 +8,7 @@ psize=Psize.dat
 hires_step=0.5
 
 [out]
+margin=0.005
 #no_breakwater=True
 root=out
 sub=bathy_sub.npy
diff --git a/data/processing/subdomain.py b/data/processing/subdomain.py
index 06e3c16..8ccc6a4 100644
--- a/data/processing/subdomain.py
+++ b/data/processing/subdomain.py
@@ -26,8 +26,9 @@ domain = np.stack((artha, buoy))
 domain.sort(axis=0)
 log.debug(f"domain: {domain}")
 
-domain[0] -= 0.002
-domain[1] += 0.002
+margin = config.getfloat("out", "margin", default=0.002)
+domain[0] -= margin
+domain[1] += margin
 log.debug(f"domain: {domain}")
 
 inp_root = pathlib.Path(config.get("inp", "root"))