The tale of two buckets - part one.
I am lucky. Well, at least I think I am.
My current vocation intermingles with my other. Surveying and my 'daytime job' as the operations manager within the charter industry.
From this standpoint, I present to you the tale of two buckets.
I could not think of another title that would be as catchy as this. However, the story's facts revolve around what a surveyor can not see and what an operations manager can. With these tools at my disposal, I am often confronted by the question of 'how do you know that without knowing' during a survey.
Here we have two buckets. What you are looking at is the contents drained from a sail drive. The milky white transmission oil is appropriately in the white bucket, and what it should look like is in the blue bucket. Sail drives are almost commonplace on catamarans and within the market and production of monohull sailboats. Gone are the stern gland, shaft, and fixed propellor, substituted with the space-saving sail drive.
The unit has to be maintained out of the water, and should a wayward line get wrapped around the propellor; this can accelerate, if not almost guarantee what you see above.
Here is an example. You approach a mooring ball. The pace is a little too quick. You back down on the engine, there is a noise, and suddenly the low oil pressure alarm sounds; the engine has stopped, and there is confusion. The dinghy is much closer to the stern, and slowly, the penny drops. The dinghy painter has been sucked beneath the hull and found the propellor.
This, in turn, from the above action, is what you may find.
The propellor has some slightly noticeable movement around the hub; it can be rocked back and forth. The only safe bet is to remove the propellor to see if the sacrificial propellor hub has moved, and low and behold, fibers are present from a line, or the collar has been so tightly constricted it has been ripped away, allowing the prop to sit onto the leg causing metal to metal contact and wear, the ever-increasing evidence can mount from just viewing the prop. There are other tells as if left undisclosed or untold, the unbalanced prop will feed back a wobble to the engine, amplified by the engine mount, and the paint will start to flake from the edges of the blades as the flat circle is now elongated of the revolution.
What must be factored in is what can happen next.
The oil seals are most definitely compromised; if not, their life span has been greatly shortened. It can get worse. Fibers, especially fishing lines, can penetrate the seals and migrate further; in the worst case, (I have seen) fibers have gone into the bearings.
Now we have a scenario of no lubrication and bearings bound by foreign material.
If we scale the scenario up, the engine will have one at least damaged engine mount, which requires two to be changed. The damper plate will or may develop a rattle, must be inspected, and is likely to require replacement.
On the very far end of this is the most dramatic of all, the full-tilt boogie of wraps that can rip the entire leg away from the skirt and the vessel. Ingress of water is rapid. The heart rate and repair bill will also keep the blood pressure high.
The photo above - shows fibers within the bearing race. The bearing race has worn, and the shaft scored.
All the parts are fixable, and the yard will be happy to see you as the vessel must lift out for repairs.
In my scenario in the charter industry, the customers are unhappy each time I explain cause and effect, which equals a dented deposit. Sometimes it's not all self-evident, and a period is required for the transmission to produce cream cheese, but it does eventually.
From a surveyor's point of view, should I find evidence of a wobbly propellor, it is always noted with some vigor in my report, once to the cry of the broker saying, 'it's fine, they are all like that.' To which end, he was proven very wrong.
So, dear reader, the next time someone mentions, 'oh, it was OK; it was only a light wrap,' remember my words above of the tale of two buckets.
In the photo above - the fishing wire was the culprit for this prop wrap.
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