new System.disconnectLineEnd method does like it says

moorpy/Catenary.py

@@ -1428,7 +1428,8 @@ def step_func_cat(X, args, Y, info, Ytarget, err, tols, iter, maxIter):
 
 
     # Tricky case for sloped seabed (prone to overestimating LBot unless trapped corrected in the solve)      
-    (fAH1, fAV1, fBH1, fBV1, info1) = catenary(121.5, 17.5, 138.5, 1232572089, 2456.8, CB=0.0, alpha=-2.6, HF0=428113, VF0=396408, Tol=0.0005, nNodes=41, plots=1)
+    #(fAH1, fAV1, fBH1, fBV1, info1) = catenary(121.5, 17.5, 138.5, 1232572089, 2456.8, CB=0.0, alpha=-2.6, HF0=428113, VF0=396408, Tol=0.0005, nNodes=41, plots=1)
+    (fAH1, fAV1, fBH1, fBV1, info1) = catenary(121.09772794232714, -1.8384100597014594, 101.50770310432262, 1232572089.6, 2456.820077481978, CB=0.0, alpha=-0.8659609923714943, HF0=20534.12538249187, VF0=53055.020668169294, Tol=0.0005, nNodes=41, plots=1)
 
     """
     Tol =2e-05

moorpy/body.py

@@ -105,11 +105,6 @@ def attachPoint(self, pointID, rAttach):
             The identifier ID number of a point
         rAttach : array
             The position of the point relative to the body's frame [m]
-
-        Returns
-        -------
-        None.
-
         '''
 
         self.attachedP.append(pointID)
@@ -118,6 +113,23 @@ def attachPoint(self, pointID, rAttach):
         if self.sys.display > 1:
             print("attached Point "+str(pointID)+" to Body "+str(self.number))
 
+    """
+    def dettachPoint(self, pointID):
+        '''Removes a Point from the Body.
+        
+        Parameters
+        ----------
+        pointID : int
+            The identifier ID number of a point
+        rAttach : array
+            The position of the point relative to the body's frame [m]
+        '''
+    
+        find pointID index in self.attachedP
+        delete entry from self.attachedP and rPointRel
+        
+        set point type to free
+    """
 
     def attachRod(self, rodID, endCoords):
         '''Adds a Point to the Body, at the specified relative position on the body.

moorpy/point.py

@@ -88,11 +88,6 @@ def attachLine(self, lineID, endB):
             The identifier ID number of a line
         endB : boolean
             Determines which end of the line is attached to the point
-
-        Returns
-        -------
-        None.
-
         '''
 
         self.attached.append(lineID)  
@@ -108,15 +103,16 @@ def detachLine(self, lineID, endB):
             The identifier ID number of a line
         endB : boolean
             Determines which end of the line is to be detached from the point
-
-        Returns
-        -------
-        None.
-
         '''
 
-        self.attached.pop(self.attached.index(lineID))
-        self.attachedEndB.pop(self.attachedEndB.index(endB))
+        # get attachment index
+        i1 = self.attached.index(lineID)
+        i2 = self.attachedEndB.index(endB)
+        if not i1==i2:
+            raise Exception("issue with the right end of the line to detach...")
+
+        self.attached.pop(i1)
+        self.attachedEndB.pop(i1)
         print("detached Line "+str(lineID)+" from Point "+str(self.number))
 
 

moorpy/system.py

@@ -339,7 +339,36 @@ def removeLine(self, lineID):
             raise Exception("Invalid line number")
             
     """    
+
+    def disconnectLineEnd(self, lineID, endB):
+        '''Disconnects the specified end of a Line object from whatever point
+        it's attached to, and instead attaches it to a new free point.
+        '''
+
+        # for now assume the line is at the expected index
+        line = self.lineList[lineID-1]
+
+        if not line.number == lineID:
+            raise Exception(f"Error lineID {lineID} isn't at the corresponding lineList index.")
 
+        # detach line from whatever point it's attached to
+        for point in self.pointList:
+            if lineID in point.attached:
+                if point.attachedEndB[point.attached.index(lineID)] == endB:
+                    point.detachLine(lineID, endB)
+                    break
+
+        # create new free point to attach the line end to
+        if endB:
+            r = line.rB
+        else:
+            r = line.rA
+
+        self.addPoint(0, r)
+
+        self.pointList[-1].attachLine(lineID, endB)
+
+
     def addLineType(self, type_string, d, mass, EA, name=""):
         '''Convenience function to add a LineType to a mooring system or adjust
         the values of an existing line type if it has the same name/key.