More on the endlessly fascinating topic of propeller nuts. This mystery got lost in all the traveling and haul out bustle and I forgot about it until I ran across the nut while cleaning up the boat yesterday.
When the boat was hauled, the propeller lock nut was found to be cracked. It was put on (wrong way around, of course) by a diver and thus under less than optimum working conditions.
This is what it looks like:
Ah Ha! You say, that's why the big nut should go on last. However, the nut was tight even with a crack just as wide as seen in the photo. The big nut was tight and the prop was firmly seated. There was nothing to indicate that anything had moved.
The diver was a big guy but over torquing usually results in stripped threads, not nut cracking. I thought perhaps the pipe wrench (Why is it that prop nuts never seem to fit standard wrenches?) pulled it apart but the wrench indentations are on the wrong side of the break.
H & H Propeller said that they have never seen or heard of anything like this. It just went on at the end of April and there were no signs of corrosion.
The best theory I can come up with is that the nut was tapped improperly to a sup standard hole size (tapered tap not run fully through?) and popped when forced on. There are lots of holes in that theory though. The threads on both the nut and shaft look perfect. The measurements inside the threads in line with the crack and perpendicular to it are the same. The crack doesn't appear to have spread the nut.
Anybody got a better theory?
When the boat was hauled, the propeller lock nut was found to be cracked. It was put on (wrong way around, of course) by a diver and thus under less than optimum working conditions.
This is what it looks like:
Ah Ha! You say, that's why the big nut should go on last. However, the nut was tight even with a crack just as wide as seen in the photo. The big nut was tight and the prop was firmly seated. There was nothing to indicate that anything had moved.
The diver was a big guy but over torquing usually results in stripped threads, not nut cracking. I thought perhaps the pipe wrench (Why is it that prop nuts never seem to fit standard wrenches?) pulled it apart but the wrench indentations are on the wrong side of the break.
H & H Propeller said that they have never seen or heard of anything like this. It just went on at the end of April and there were no signs of corrosion.
The best theory I can come up with is that the nut was tapped improperly to a sup standard hole size (tapered tap not run fully through?) and popped when forced on. There are lots of holes in that theory though. The threads on both the nut and shaft look perfect. The measurements inside the threads in line with the crack and perpendicular to it are the same. The crack doesn't appear to have spread the nut.
Anybody got a better theory?
