Dave Howell, Nellie D. 37VT63
We have a good head of stream on when, all of a sudden, there's a loud bang and Nellie emits a big cloud of black smoke from the exhaust. Bicki and I exchange a brief anxious look before Bicki throttles down and I dive into the engine room. I look at the engine's raw water seacock. It's closed. Oops.
When doing engine room checks I rely on the mnemonic WOBBS--water, oil, belt, bilge, strainer. This mental checklist worked great until today, and then it failed miserably. In retrospect it wasn't the routine that failed, it was its application.
The duckweed (pictured below in Lock 16) in was so thick in Muscatine, Iowa that the Mississippi looked more like a lawn than a river. When doing the WOBBS check, and knowing how thick the duckweed was, I decided to open and clean the strainer rather than do just the normal, external, visual inspection. And, this leads us to the crux of the problem. WOBBS is really a preflight inspection--the last thing that should be done before starting the engine. If the inspection leads to some maintenance actions, like adding oil or coolant, then the entire WOBBS inspection should be performed again.
Since this incident we've added a raw water flow alarm. There are some good ones on the market like Borel's. Nellie's is simply a 140°F sensor/switch that's nylon tied to the 3" exhaust hose just downstream of the exhaust elbow. There are only two wires to connect: one goes to ground; the other to the alarm trigger used by the oil pressure sending unit. For $1 in parts and a little labor, the alarm is a lot of bang for the buck.
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