The sound of No Water in the Exhaust

We had chartered a 38' Athena Cat in Belize and had to motor a short distance one day due to lack of wind. While underway I heard the hollow echo of no water coming out of the port engine and asked a crew member to check the exhaust to see if there was water coming out - there was not so I shut down the engine. The engine did not overheat and no alarm sounded because we heard it and took action ahead of time. We contacted the charter company and they recommended someone at the South Water Cay to look at the engine. The culprit was a small octopus that had made it through the raw water system all of the way to the heat exchanger. We had to use needle nose pliers to remove calamari from the tubes in the exchanger. The lesson is to listen and smell for things out of the ordinary and take action quickly before it becomes a real problem.