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Join Date: Sep 2005
Location: New Westminster, BC
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Definitely a plug for a Signet speed/knotmeter transducer. The red cap should turn out 1/4 turn or so and the plug lifts straight out. (it's O-ring sealed). Be sure to be ready to put it or a replacement back in in a hurry, you'll be amazed how much water tries to come up that little 1" hole!
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)