The biggest problem with a sailboat is its motor

Today we went up to Freeport ME with my mother in law and took the sailboat out for a spin. It worked well. After the repair of the exhaust riser the engine seemed to smoke too much but the motor seemed to work well. It didn’t show any problems except the smoke during our week long cruise over the 4th of July. A friend said that the smoke could be due to a blocked exhaust and the cutoff valve at the transom was a potential culprit. I played with the valve and managed to shut it off completely with no hope of re-opening as it was very corroded. The marina fixed it but when I went to start the motor the next weekend there was no cooling water in the exhaust. Back to the shop and this time they cleaned the heat exchanger which they had previously taken apart and removed the scale that was plugging the nozzle that injects water into the exhaust. I guess that they never flushed it. Today there was plenty of water in the exhaust and very little smoke. I was correct about the problem. However, trying to leave the dock after leaving off my mother in law the motor would not start. I banged the starter and the connection to the battery with a hammer and it took. I guess that the starter is the next problem. I hope that the connection to the starter is the problem as it has been before rather than the need for a new starter.