Wet again

The dinghy engine is acting up again. Not to big a surprise. It has been raining on and off the last couple of days. My guess is that moisture has been getting into the fuel tank as the air vent does not screw down tightly. So its putt putt and occasionally buzz buzz. I stopped in the Yacht Haven Grand marine store to get some SeaFoam. They have every cleaning product imaginable, wine starting at $90 per bottle, and cases of water at $19.99. Do they have SeaFoam? Or any other useful product? Of course not!