It was a beautiful weekend at the marina.
The intense heat of the Houston summer had finally abated, and we slept in the V-berth sans air-conditioner for the first time since April.
Although I'd seen tiny, ethereal jellies from time to time, this was the first time I'd ever seen large cabbagehead jellyfish undulating along the bulkheads. I assume it's because the normally brackish water of Clear Lake has gotten saltier and saltier as the Texas drought has continued.
Due to various combinations of high winds, low tides and busy schedules, we hadn't been sailing in over a month, so I was excited to get out on the water Sunday morning. Unfortunately, as we started motoring out of the marina, the raw water flow disappeared and white steam started rising from the exhaust.
I watched the temperature rising past 180 degrees f as we made our way to the channel, so I turned the boat around and made it back to the dock just as it was passing 200.
The troubleshooting began with the raw water strainer. The basket did have an assortment of barnacles and other strange looking clams or whatnot inside, but not enough to be restricting water flow, so I dumped it and proceeded to check the impeller. The impeller, which is less than two years old, still looked like new. However, opening the pump housing did cause a 30-minute delay while I came up with some paper and a razor blade to cut a new paper gasket.
I blew back through the raw water line with no trouble and could hear the bubbles flowing out from under the boat. I ran a test, but there was no improvement.
Next I pulled the mixing elbow off the exhaust. It did have some carbon build-up but nothing extreme enough that I thought it would have hindered exhaust pressure or caused a hot spot that could be steaming the water. Even so, I spent another half an hour chipping and scrubbing out the carbon before putting it back together. No improvement.
The heat exchanger itself never cooled down enough for me to drain it, and I wasn't in the mood to wait around, so I left that for next weekend.
Either I have some very clogged tubing in the heat exchanger or as several people suggested on cruisersforum.com, the metal center of the impeller has become separated from the rubber, so under high RPMs, the metal is just spinning and the rubber is not.
Guess I'll continue my troubleshooting next weekend, but such is the life of a boat owner.