Windlass Failure

[migs]

Recently, our electric windlass failed whilst we were anchoring; the clutch suddenly let go and the chain ran out uncontrollably. The attached photo shows the broken part compared with a new one; it's the bit where you insert a winch handle to operate the windlasses’ clutch, and it screws into the end of the gypsy’s shaft to tighten the clutch plates.

Has anyone else experienced a failure like this, and does the photo give any clue as to why the part failed?

 

[Boathook]

What make of windlass ?

The broken part looks like a poorly cast item that has been machined.

 

[migs]

It's a Quick Hector HC1012 1000W.

 

[vyv_cox]

I looked at the photo but resolution is so poor that no detail can be seen. It is in the wrong location for fatigue and does not look right for stress corrosion (material not known). My first thought agreed with Boathook's post.

 

[sailorbenji]

It's stainless 316 from memory of dissecting one of these in the past. I much prefer the ones where the whole gypsy cap acts as the clutch tensioner/brake for this very reason, it does look like an obvious weak spot, and an area water will naturally sit.

 

[davidej]

What make of windlass ?

The broken part looks like a poorly cast item that has been machined.

A blow-hole in thr casting - at the natural point of weakness??

 

[KompetentKrew]

I looked at the photo but resolution is so poor

Is this any clearer?

 

[vyv_cox]

Is this any clearer?

Yes, much better. Is there supposed to be a hole in the centre?

 

[Boathook]

Yes, much better. Is there supposed to be a hole in the centre?

The original picture of a new one shows a hole in the centre, but the busted one seems to be to one side, unless it is due to the angle that the picture was taken at.

 

[thinwater]

How is the rode secured when setting, at anchor, and when breaking out? Samson post? Snubber?Chain lock? Or is the rode belayed to the windlass?

 

[migs]

The hole in the threaded part of new one is just a small pocket in the top, and only a few mm deep (maybe for machining the part?)

Perhaps the hole in the broken piece was created during the failure, or maybe it's a void in the casting. If so, it was an accident waiting to happen...

The failure occurred soon after we had dropped the anchor as were laying out the chain i.e before any pull tests, or attaching the snubber. Because we were getting a bit close to a moored boat, we decided to shorten the chain; however, when I pressed the windlasses' 'up' button, there was a loud bang, and the chain immediately ran out. At first I thought that the clutch was slipping, and put the winch handle back in the windlass to tighten the clutch; at this point the bush (the broken part) simply fell out of the end of the windlass.

Here are some close-up photos of the fracture.

 

[KompetentKrew]

Yes, much better. Is there supposed to be a hole in the centre?

I've edited post #7 to include the image of the replacement too.

 

[thinwater]

The hole in the threaded part of new one is just a small pocket in the top, and only a few mm deep (maybe for machining the part?)

Perhaps the hole in the broken piece was created during the failure, or maybe it's a void in the casting. If so, it was an accident waiting to happen...

The failure occurred soon after we had dropped the anchor as were laying out the chain i.e before any pull tests, or attaching the snubber. Because we were getting a bit close to a moored boat, we decided to shorten the chain; however, when I pressed the windlasses' 'up' button, there was a loud bang, and the chain immediately ran out. At first I thought that the clutch was slipping, and put the winch handle back in the windlass to tighten the clutch; at this point the bush (the broken part) simply fell out of the end of the windlass.

Here are some close-up photos of the fracture.

So this time it sounds like the weight of the boat may have come on the windlass, or may not.

What is the usual practice for securing the chain?

• If that was a void in the casting, yup, that is bad.
• If you are using the windlass to stop the boat, for example, that is more than some of them can bear. The rode should be cleated or stopped by some other means.

 

[migs]

Thanks everyone for your inputs.

We always use a snubber (secured to a boat cleat) when anchored - see photo. When the windlass failure occurred the boat was stopped, and so the situation was exactly the same as pulling the anchor up as normal.

On other points raised in the thread, we would expect a windlass to survive breaking out an anchor, as fitting a snubber every time you did this would be impractical. To break out our anchor, we move the boat forwards when the chain is up-and-down, so for us, a windlass wouldn't be much use if it couldn't hold the chain whist doing this. And what if the anchor snagged on a rock; surely it shouldn't be destroyed every time this happens? Inevitably, at some point an anchor chain will catch on something, and at a cost of some £2k5, a windlass shouldn't simply fall apart at this point.

The reason for my original post is that I have a suspicion that the failure was caused by a manufacturing defect and was interested in other people's opinions.

 

[Neeves]

Thanks everyone for your inputs.

We always use a snubber (secured to a boat cleat) when anchored - see photo. When the windlass failure occurred the boat was stopped, and so the situation was exactly the same as pulling the anchor up as normal.

On other points raised in the thread, we would expect a windlass to survive breaking out an anchor, as fitting a snubber every time you did this would be impractical. To break out our anchor, we move the boat forwards when the chain is up-and-down, so for us, a windlass wouldn't be much use if it couldn't hold the chain whist doing this. And what if the anchor snagged on a rock; surely it shouldn't be destroyed every time this happens? Inevitably, at some point an anchor chain will catch on something, and at a cost of some £2k5, a windlass shouldn't simply fall apart at this point.

The reason for my original post is that I have a suspicion that the failure was caused by a manufacturing defect and was interested in other people's opinions.

Slight drift, I'm not so keen on how you route your snubber, can it not pass through a dedicated gap, a fair lead, in the toe rail. Another option is to run it over the bow roller, on top of the chain, but thread the snubber through hose pipe and then the hose pipe protects the snubber at the point it is under tension and in contact with the chain. Your snubber seems to be simply a device to take the tension off the windlass and stop the chain rattling - which is good - but its far too short to offer any 'snubbing' (elasticity) ability. To offer elasticity it really needs to be about deck length.

You are correct - it would be unreasonable for a windlass not to be designed to take snatch loads - if you are retrieving and a MoBo goes past creating chop then the chop will create a snatch - and the windlass should not fail under those or similar conditions.

Another piece of thread drift. Maxwell supply a handle, looks like a winch handle, to retrieve the rode by hand on their, or some of their. windlass The device fits into the top of the windlass and you grind away - simple stuff. But its actually not a winch handle and a winch handle does not replace the Maxwell supplied object. The Maxwell handle has a recess in the centre of the 3/4" square part that fits into the the hole in the female portion in the windlass and there is a protrusion at the bottom of the female receptor. So a real winch handle does not seat correctly, it stand proud - sitting on the protrusion.

Why its designed not to take a winch handle is a mystery.

I recall maybe incorrectly Maxwell have an extender - so that you can winch by hand more comfortably - its just a rod, like a socket set extender, and maybe your hole serves some sort of similar purpose

I wonder if the hole in your failed portion is to take a dedicated device as part of hand retrieval.

Jonathan

 

[thinwater]

Thanks everyone for your inputs.

We always use a snubber (secured to a boat cleat) when anchored - see photo. When the windlass failure occurred the boat was stopped, and so the situation was exactly the same as pulling the anchor up as normal.

On other points raised in the thread, we would expect a windlass to survive breaking out an anchor, as fitting a snubber every time you did this would be impractical. To break out our anchor, we move the boat forwards when the chain is up-and-down, so for us, a windlass wouldn't be much use if it couldn't hold the chain whist doing this. And what if the anchor snagged on a rock; surely it shouldn't be destroyed every time this happens? Inevitably, at some point an anchor chain will catch on something, and at a cost of some £2k5, a windlass shouldn't simply fall apart at this point.

The reason for my original post is that I have a suspicion that the failure was caused by a manufacturing defect and was interested in other people's opinions.

I agree with you on this. But it also would not be a the first time equipment was designed without the real world in mind. Even without the casting flaw, that part looked pretty spindly for the load.

 

[vyv_cox]

Your photo in post #7 shows a good deal of clashing/polishing, which is characteristic of a progressive crack, common in fatigue failures. I see in your later photo that the fracture is coincident with the start of the threaded portion, again a likely initiation point for fatigue. I cannot see any beach marks but there is so much subsequent surface damage that this is not unexpected. It does seem that the part is very 'spindly' as suggested by Thinwater, which again supports the suggestion that this may be a high stress, low cycle fatigue failure.

Of course, if there is more porosity this would be a strong contributor.

 

[migs]

Vyv, many thanks for your expert analysis. Let's hope we have better luck with the replacement part. A week before the windlass failed, we were anchored in La Grande Greve off Sark (see pic); at least it didn't let go whilst we setting the anchor here...

So to summarise your comments:

* The design of the clutch mechanism is far from perfect
* The 'bush' that does the tightening is undersized for it's intended use
* The bush may well have had a manufacturing defect such as a void in the casting

So, essentially it is not fit for purpose.

 

[migs]

I've now extracted the broken thread part of the bush from the windlass (above)
And here is a photo of the thread in situ (below)

Again, surely there shouldn't be a hole in the casting at the weakest point?

 

[vyv_cox]

Yes, poor design. It has failed exactly where you might expect it to.