SD and/or others,
Curious to as to what everyone believes is "heats up noticeably" when referring to a SB.
I think I'm well-positioned to take this one
When I first installed Gore GTU (or GFO, don't recall which) season before last, I was interested in getting the drip rate to as close to the once-every-20-seconds recommendation as humanly possible. It was at 1/10-secs. To make a long story short: Couldn't do it. It was either 1/10-secs. or so, or (nearly) none at all, and I'm talkin' just a slight >< change in packing gland nut tightness. In my experiments I once had a synapse lapse and, after having tightened the nut just one RCH, forgot to subsequently check the drip rate until after we'd been under way on the iron genny for quite some time. Remembered. Went down and checked. No drip at all! Felt the stuffing box. Not just warm, but HOT!
Luckily there was a public seawall marina right there, so we quickly pulled her over, tied up and I addressed the situation.
When the packing gland was dripping again, it dripped gray.
Another time, when the drip rate was really slow, after one of these adjustments, like one every minute, the stuffing box was noticeably warm to the touch, but not hot.
When it's dripping at about one every 10 sec. or so, it's not even noticeably warm to the touch.
Fast-forward to this spring, when the stuffing box coupling hose was replaced by our yard. He made it slightly longer than the old one, so the packing material would be on a different part of the shaft, but he said it hadn't been necessary as the shaft was un-scored, and, he said, the packing material looked essentially brand new, so he re-used it.
That Gore stuff is remarkable.