The 33 meter long tug Skuld collided with a rig in the port of Esbjerg, Denmark.   The Skuld was towing the drilling rig along side two other tugs when tug suffered engine failure.   The Skuld continued forward until it struck the rig.   The Skuld suffered severe water ingress as the hull was holed below the waterline.   The other two tugs came to the aid of the Skuld and towed it back to port.   The Skuld was berthed at a quay where the local fire brigade had pumps waiting.  No reports of injuries.   Authorities have placed booms around the Skuld as some diesel fuel pollution was released in the port.