Jean and I had spent the evening in Vergennes, Vermont tied up on the community dock after a cruise up from Whitehall, New York. We departed just before 6 a.m. for a seven-mile trek out the Otter Creek River before joining Lake Champlain. The water was like a mirror, and gentle wisps of steam stood sentinel along the bank. If you leave early enough sometimes, you will see wildlife on the shore, and we were fortunate enough to see deer this time. About 25 minutes into our idle out the river I notice a harmonic change in the engine sounds and checked my gauges and saw that the port engine was beginning to overheat. I asked Jean to take over and continue to idle out the river on the starboard engine while I went below to see what could be the cause of the overheat. The port engine has been the most dependable thus far the entire trip, and I was not sure what I was going to find. I checked the valves on the water feed to ensure that the engine was receiving water from the outside and then made sure the engine had not sprung a leak in the heat exchanger. After finding no leaks and no pools of water anywhere, the next check would be to see if the impeller was operating correctly. I had all the impellers replaced before we left on the loop and thought that it was odd that they would be in need of replacing so soon. I had not changed an impeller before and was not sure on procedures but forged ahead anyway since there were no services available in Vergennes. Jean was doing a great job of keeping us in deep enough water on one engine, and we had time before we entered Lake Champlain again.
The impeller housing on the Ford Lehman engine is a straightforward affair with several small screws on a face plate, so I started there. All of the screws came out without any problems, and I was able (this time) not to drop any of them down into the bilge. The faceplate was removed, and I was amazed at the condition of the rubber impeller. Only the hub was left.
None of the fins were on the hub but laying in the chamber. The hub was removed without any difficulty, the chamber cleaned of debri, and then replaced with a spare impeller I brought along. A gasket was installed, and the faceplate screwed back on, and with an engine restart, the temperature dropped immediately back to normal. A few lessons learned from this experience were: always to have spares onboard, to take your time and assess the problem and then begin with the apparent culprits first working towards the solutions. Trust your co-captain to take care of their part, and to carry on.