Elan 333 rudder failures

[ELAiNe333]

Meanwhile, perhaps the Elan 333 should be renamed the Rutland Reindeer.

Am I being thick or is this too obtuse? Ijust don't get the comment.
If referring to shedding antlers, the breed would soon die out if only two of a herd of 500 shed their annual growth.
Rutland?

 

[ELAiNe333]

X-rays would theoretically show up a crack in the stock without removing the surrounding GRP. It would not be an easy task but could well be worth asking a NDT specialist to advise. It would need an isotope to be taken to the boat as presumably removing the rudder would be problematic. Your Yellow Pages should have names to contact. Your profile doesn't say where you are so I cannot suggest anyone.

The next step would be to cut away some GRP and use dye-penetrant but this would probably be rather hit-or-miss. Eddy current might well work if access to each side of the crack site was possible. Ultrasonic probes really need access from a position transverse to a crack, which would be virtually impossible. Other than the dye-pen, again specialist companies are your only option.

.

Thanks for your analysis. Actually removal of the rudder is fairly easy, I did so a year or so ago to look at the bearings. The only thing to watch is that the unit is even heavier than you expect. Another pair of hands would have made the replacement easier.
We sail on the East coast if you have any recommendations for a testing house.

 

[Lucky Duck]

As an aside, I passed a shallow draft version of the Elan on the hardstanding last weekend and was a bit surprised to see that the rudder was about a foot deeper than the keel (presumably the shallow and deep draft versions share the same rudder design).

This seemed a far from ideal arrangement.

 

[JumbleDuck]

Am I being thick or is this too obtuse? Ijust don't get the comment.
If referring to shedding antlers, the breed would soon die out if only two of a herd of 500 shed their annual growth.
Rutland?

It's a metal fatigue literary reference:

http://en.wikipedia.org/wiki/No_Highway

 

[vyv_cox]

It's a metal fatigue literary reference:

http://en.wikipedia.org/wiki/No_Highway

Brilliant author: I still have all his books. His autobiography is particularly good, highlighting the differences between the R101 and R100, one built by the government and the other by private industry. Shute was the mathematician on the R100. The crash of the government one (R101) killed off the airship for ever.

 

[mjcoon]

It's a metal fatigue literary reference:

http://en.wikipedia.org/wiki/No_Highway

Thanks for that article reference. I knew about the Comet window fatigue crashes (it's been on TV often enough!) but not the fictional precursor.

Mike.

 

[ELAiNe333]

It's a metal fatigue literary reference:

http://en.wikipedia.org/wiki/No_Highway

Apologies, it was my lack of knowledge.

 

[West Coast]

Brilliant author: I still have all his books. His autobiography is particularly good, highlighting the differences between the R101 and R100, one built by the government and the other by private industry. Shute was the mathematician on the R100. The crash of the government one (R101) killed off the airship for ever.

Agreed, ' Trustee from the Toolroom' was one of my favourite books from when I first found his books way back, very cleverly written

 

[ELAiNe333]

As an aside, I passed a shallow draft version of the Elan on the hardstanding last weekend and was a bit surprised to see that the rudder was about a foot deeper than the keel (presumably the shallow and deep draft versions share the same rudder design).

This seemed a far from ideal arrangement.

Far worse than having the deep keel version, pushing your luck along a shelving East coast estuary shoreline to evade the tide is one thing with a keel, but to be caught by the rudder?

 

[Lucky Duck]

I'd be very cautious about crossing the concrete cill at Woodbridge Tidemill, its one thing scrape the barnacles off the bottom of the keel when being a bit optomistic about the depth or ones draft but doing it with the rudder could be rather expensive.

 

[ELAiNe333]

I'd very cautious about crossing the concrete cill at Woodbridge Tidemill, its one thing scrape the barnacles off the bottom of the keel when being a bit optomistic about the depth or ones draft but doing it with the rudder could be rather expensive.

The marina there always swear the tideguage is accurate but we have come to a gentle halt there when the guage says 2M and we draw 1.95M, perhaps too many beer bottles stored aboard.

 

[JumbleDuck]

Apologies, it was my lack of knowledge.

Not at all. I was being mischievously gnomic. It's a great book, are as all the author's, and a remarkable presage of the Comet disasters.

 

[Leighb]

The marina there always swear the tideguage is accurate but we have come to a gentle halt there when the guage says 2M and we draw 1.95M, perhaps too many beer bottles stored aboard.

The deepest point is not in the centre, but more to the North, have a look at low water and see where it is trickling out, there may be around 0.2 difference at a guess, just enough to squeak through, or not as the case may be.

 

[PeterWright]

Nevil Shute Norway, Engineer

Shute was the mathematician on the R100.

Hi Vyv,

I too still have most of the books Shute wrote, and as a fellow engineer, I read your posts and advice here with interest. However, I can't let your description of Mr Norway's part in the R100 project pass without comment. The title of his first role on the project was Chief Calculator, but today he would more likely be called Chief Structural Engineer or Chief Stress Engineer, both of which descibe better the role he performed. By the time the project was wound up, he had been promoted to Chief Engineer, succeeding Barnes Wallis. At any rate, Nevil Shute Norway was not a mathematicin but an engineer through and through, as well as a brilliant author.

Pete

 

[Bilgediver]

The news section of the February YM includes a piece on fatigue failures of two Elan 333s, plus a photograph. A representative of the company seems to be blaming 'a machining imperfection present when the rudder stock was first supplied to Elan'. My inspection of the photograph suggests that the fracture is absolutely textbook for the design of the stock, occurring at the lower end of a change of section (which may be what Elan are saying in 'wriggle words').

I have investigated very many fatigue failures (see page 76 of the same issue of YM). Elan suggest that this particular rudder stock had accumulated an unusually high number of cycles, which may well be true. My reading of the design is that this would be categorised as a high stress, low cycle situation, the number of cycles to failure being measured in thousands, rather than tens of millions as would be the case with the more normal design brief of low stress, high cycle. Failure of a stock to the same design is thus inevitable, it is simply a matter of time. Anyone owning one of these boats would be well advised to take up the offer of a replacement at cost price, although if the boat is relatively new I would be pushing for a reduction or free replacement on the grounds that it is unfit for purpose.

+1


Yes it did seem to be a text book case

 

[vyv_cox]

The title of his first role on the project was Chief Calculator,

It's a long time since I read it. My memory, undoubtedly not fault free, said mathematician, not too far removed from calculator I guess. Undoubtedly he was an Engineer, a long way removed from those of the same name today who empty bins, fix central heating and replace electric cables blown down in storms.

 

[PeteCooper]

It's a great book, are as all the author's, and a remarkable presage of the Comet disasters.

Let's hope that not all his books where visions of the future ... he also wrote 'On The Beach'

 

[JumbleDuck]

I too still have most of the books Shute wrote, and as a fellow engineer, I read your posts and advice here with interest. However, I can't let your description of Mr Norway's part in the R100 project pass without comment. The title of his first role on the project was Chief Calculator, but today he would more likely be called Chief Structural Engineer or Chief Stress Engineer, both of which descibe better the role he performed. By the time the project was wound up, he had been promoted to Chief Engineer, succeeding Barnes Wallis. At any rate, Nevil Shute Norway was not a mathematicin but an engineer through and through, as well as a brilliant author.

He was also an aircraft designer and was mainly responsible for the Airspeed Tern, one of the very first British gliders.

As a mathematician and an engineer, by the way, I see no conflict between the two job descriptions!

 

[JumbleDuck]

Let's hope that not all his books where visions of the future ... he also wrote 'On The Beach'

A truly horrible book, and by that I don't mean bad. It's been a while since I read it, but the memories send shivers down my spine. The image of parents killing their children to save them from a worse death is particularly nasty, and reminds me of the scene in Untergang/Downfall where Magda Goebbels is shown killing all her children, one by one, in pitiless detail.

 

[Sailfree]

It's a long time since I read it. My memory, undoubtedly not fault free, said mathematician, not too far removed from calculator I guess. Undoubtedly he was an Engineer, a long way removed from those of the same name today who empty bins, fix central heating and replace electric cables blown down in storms.

IIRC Nevil Shute also wrote in the front of one of his books "An Engineer is a person that can do what any other idiot can do but in half the time and at half the cost".

It was reading "Trustee from the Toolroom" as a 14yr old trainee for a Borstal residence in an inner London council estate that made me consider that there might be wider horizons and it would be nice to own a sailing boat. The book never mentioned the marina costs!!