Replace rigging screws or not?

[Kukri]

I've not seen bronze wire. Or other parts much. Have you?

Yes, long ago. It used to be specified for centreplate hoisting cables. But I have not seen any for years. A most interesting thread, btw.

 

[JumbleDuck]

Out of interest, who maintained your glider? As I understand it, in civil leisure aviation on powered craft, arent some inspections ans servicing mandated by qualified pros?

It has largely changed since I was flying as most gliders are now fully registered civil aircraft and subject to much more stringent rules. When I had mine it was all supervised by the British Gliding Association. After I bought it I did almost all the work needed myself. checked and signed off by BGA inspectors when necessary. Annual Certificate of Airworthiness inspections were done by BGA inspectors - mostclubs had at least one and I would act as assistant. Glider aren't particularly complicated, but if you get it wrong things can be very awkward.

 

[JumbleDuck]

I’ve got a simpler solution. Titanium. Grade 5. Bullet proof and nowadays not terribly expensive.

By odd coincidence, I yesterday found a 1/4" diameter titanium specimen from my tensile testing days. Amazing stuff.

 

[zoidberg]

Has to be the ultimate solution with the only problem being no one as yet are mass producing fittings for boats

Ahem!

Now all I need is a suitable boat.....

 

[capnsensible]

Russia's Alfa-Class: The Titanium Submarine that Stumped NATO

They would have been an interesting opponent.....

 

[JumbleDuck]

Russia's Alfa-Class: The Titanium Submarine that Stumped NATO

They would have been an interesting opponent.....

As I recall, the hull of each Alfa class contained more titanium than the West produced in a year. Remarkable things.

 

[capnsensible]

As I recall, the hull of each Alfa class contained more titanium than the West produced in a year. Remarkable things.

It was interesting being involved in finding them, tracking them and developing the tactics to defeat them. My small part in their downfall.

Fortunately for us, it didnt turn out too well for the 'Reds'.

 

[john_morris_uk]

It was interesting being involved in finding them, tracking them and developing the tactics to defeat them. My small part in their downfall.

Fortunately for us, it didnt turn out too well for the 'Reds'.

Quite! I spent three very happy years in SM2. I think it was probably well after your time though.

SM2. 'Second to none'

 

[Kukri]

As I recall, the hull of each Alfa class contained more titanium than the West produced in a year. Remarkable things.

A fine example of the utter perversity of the Soviet system. Nothing in the shops, but titanium submarines.

 

[Frank Holden]

Where does it end? If you're going to renew the rigging screws, what about the chain plates, their attachment to the hull, the hull itself? It may not be a completely full proof test, but your eyes can determine if there is wear on the threads of the turnbuckles, although I really can't see how the threads would be "jiggling about".

Well, yes...
On the Sealord - which I pretty sure is what John sails - there are what are often called 'staples... a U-bolt arrangement ... difficult to explain.

Some 10% of all the Sealords built are known to have had them fail... and others probably just aren't saying....

Crevise corrosion within the deck.... I replaced mine in BA when the boat was 24 years old.... one of them failed only 4 years later... I suspect poor quality argentine metal.... and I was very lucky not to lose the rig.
Replaced them all again in NZ... increased the diameter of all of them by 2 mm...

So yes.... watch out for your chain plates....

 

[john_morris_uk]

Well, yes...
On the Sealord - which I pretty sure is what John sails - there are what are often called 'staples... a U-bolt arrangement ... difficult to explain.

Some 10% of all the Sealords built are known to have had them fail... and others probably just aren't saying....

Crevise corrosion within the deck.... I replaced mine in BA when the boat was 24 years old.... one of them failed only 4 years later... I suspect poor quality argentine metal.... and I was very lucky not to lose the rig.
Replaced them all again in NZ... increased the diameter of all of them by 2 mm...

So yes.... watch out for your chain plates....

The chain plates are on the list...

I met up with a couple on another Sealord a year of two ago when they were just completing a circumnavigation and they’d had chain plate failure.

I’ve got details of a S/S fabricator in Fareham who has made the beefed up versions in the past.

When we bought Serendipity 15 years ago, I removed all the chain plates to check them and re-bed them as they all leaked.... The slightly cranked u-bolts were in good condition, cleaned up perfectly and showed no signs of corrosion. I’ve had to re-bed two since because I made the mistake of nipping them up too tight the first time and squeezing all the Sikaflex out of the joint. I’m drifting my own thread now...

 

[vyv_cox]

Before any comparison is made it is important to explain that not all Bronze is of Naval Engineering
Standard (NES 747). This standard refers to heat treated, cast nickel aluminium bronze, which is the
preferred bronze for sea water conditions. Many bronze marine products on the market today are either
aluminium bronze or silicone bronze, these do not perform at the same level as the above. Cast bronze
can have many impurities which affect the ability to resist corrosion in a sea water environment.
Manufacturers of bronze marine fittings often neglect to clarify the type of bronze used. This should
always be checked as performance does vary.
Similarly, there are various stainless steels. The 300 series stainless steels are generally considered to
resist rust, however 304 is inadequate for marine applications, where 316 is the accepted marine grade
stainless steel. 316 shows good general resistance to corrosion and is widely used, however in certain
applications (specifically where there is no oxygen present) 316 will be susceptible to corrosion. To
increase resistance to corrosion a surface treatment such as electro polishing will provide extra
protection. Alternatively there are superior grades of stainless steel which offer almost twice the
resistance to corrosion that ordinary 316 or 316L offers. These include duplex stainless steel (2205),
super duplex SS (2507).
Research conducted in the UK comparing nickel aluminium bronze (NES 747) with various stainless
steels in an offshore sea water environment, revealed some interesting findings.
A composite ranking for resistance to corrosion was established, positioning the NiAl bronze below the
duplex stainless steels and above 316 SS.
Given that most bronze fittings are made from less noble bronzes such as silicone bronze and aluminium
bronze, which are affected more severely by galvanic corrosion, the ranking of these becomes similar to
316 stainless steel.
Research also recommended that the bronze products not be used in polluted waters.
The use of duplex and super duplex stainless steels in the marine environment is recommended as these
metals with higher levels of molybdenum and chromium, apart from being far stronger than bronze,
provide superior resistance to intergranular, pitting, crevice, galvanic and chloride stress corrosion.
Before any comparison is made it is important to explain that not all Bronze is of Naval Engineering
Standard (NES 747). This standard refers to heat treated, cast nickel aluminium bronze, which is the
preferred bronze for sea water conditions. Many bronze marine products on the market today are either
aluminium bronze or silicone bronze, these do not perform at the same level as the above. Cast bronze
can have many impurities which affect the ability to resist corrosion in a sea water environment.
Manufacturers of bronze marine fittings often neglect to clarify the type of bronze used. This should
always be checked as performance does vary.
Similarly, there are various stainless steels. The 300 series stainless steels are generally considered to
resist rust, however 304 is inadequate for marine applications, where 316 is the accepted marine grade
stainless steel. 316 shows good general resistance to corrosion and is widely used, however in certain
applications (specifically where there is no oxygen present) 316 will be susceptible to corrosion. To
increase resistance to corrosion a surface treatment such as electro polishing will provide extra
protection. Alternatively there are superior grades of stainless steel which offer almost twice the
resistance to corrosion that ordinary 316 or 316L offers. These include duplex stainless steel (2205),
super duplex SS (2507).
Research conducted in the UK comparing nickel aluminium bronze (NES 747) with various stainless
steels in an offshore sea water environment, revealed some interesting findings.
A composite ranking for resistance to corrosion was established, positioning the NiAl bronze below the
duplex stainless steels and above 316 SS.
Given that most bronze fittings are made from less noble bronzes such as silicone bronze and aluminium
bronze, which are affected more severely by galvanic corrosion, the ranking of these becomes similar to
316 stainless steel.
Research also recommended that the bronze products not be used in polluted waters.
The use of duplex and super duplex stainless steels in the marine environment is recommended as these
metals with higher levels of molybdenum and chromium, apart from being far stronger than bronze,
provide superior resistance to intergranular, pitting, crevice, galvanic and chloride stress corrosion.

Not sure where you have copied this from but it is not appropriate to the discussion. The bronze used for bottlescrews and other deck hardware is tin bronze, probably leaded. LG2 or LG4 most likely. See http://coxeng.co.uk/metallurgy/brasses-and-bronzes/ for a lot more information.

 

[cherod]

When I renewed our standing rigging fifteen years ago, I bought high quality bronze rigging screws thinking that the next time I change the standing rigging I can just replace the wire rigging.

A rigger (who comes highly recommended) has just been bending my ear telling me that I really ought to renew the rigging screws when I change the standing rigging again. I admit I've kicked the backside out of the normal change after ten years with not changing the wire earlier, but I have inspected it and until now the insurance company hasn't;t batted an eyelid. However, we've just been surveyed and the change is in the survey report so I've no choice.

With six rigging screws coming to £680 it's not peanuts, but I suppose I ought to bite the bullet. The real niggle is that the rigger kept saying, "How much do you value your life...?" I am REALLY allergic to hard sell and emotional selling which puts me right off. The total bill is over £3k which is rather more than I anticipated...

maybe the real question that the rigger is asking is how much will you pay him !!

 

[cherod]

In my industry we use bolts to hold together flanges with 15000 psi of pressure. The bolts are all specified but we have to dimensionally inspect them and perform NDT examination, with MPI and dye penetrant. Quite often the bolts are acceptable from a crack point and an overall dimension point but that the threads have started to wear down, thin out by flattening. The pressure at 15k cycles over the life of the bolt from atmospheric to 15k, so not a steady state.

I think there comes a time when our turnbuckles experience the same usage wear. In my bolt case, it is safety critical and could result in the drilling rig burning down and multiple deaths, so low cost assurance just to change them out; sort of the same logic I would apply in your case JM.

yes if there is obvious visual or NDT damage , but bronze fittings are not stainless .

 

[Mudisox]

A slight query ... what happens to the old discarded bottlescrews? I inspect mine every year along with the stays, and nothing seems to be wrong with them. Mind you they are hefty in the first place.

 

[JumbleDuck]

A fine example of the utter perversity of the Soviet system. Nothing in the shops, but titanium submarines.

And there's the US, spending more on its military than the next ten biggest spenders jointly but no proper health care system. Lunacy everywhere.

 

[Kukri]

And there's the US, spending more on its military than the next ten biggest spenders jointly but no proper health care system. Lunacy everywhere.

And we know how to disable an American nuclear powered aircraft carrier: Covid19

 

[john_morris_uk]

A slight query ... what happens to the old discarded bottlescrews? I inspect mine every year along with the stays, and nothing seems to be wrong with them. Mind you they are hefty in the first place.

I don’t know what happens usually but I’m keeping a few as emergency repairs.

 

[Rappey]

Not sure where you have copied this from but it is not appropriate to the discussion. The bronze used for bottlescrews and other deck hardware is tin bronze, probably leaded. LG2 or LG4 most likely

An article from a company that specialise in amongst other things manufacturing 2205 grade stainless valve and strainers for military, commercial and leisure I would have thought knows what they are talking about when explaining differences between various bronzes and stainless.
Since a lot of this discussion is about bronze and stainless rigging screws then why do you say my copy/paste is not appropriate?
Your saying bronze bottle screws are tin bronze?
Here is a copy /paste from your link which states -
. ‘Bronze’ rigging screws may be made from either silicon or aluminium bronze.
Hmm.
So surely your link must also not be appropriate to the discussion ?
Maybe your an expert in the manufacturing of rigging screws in which case I'm all ears.
You could have just stated that rigging screws are also made from tin bronze but you chose to state that my contribution to this thread is not appropriate .
Glad I don't have to deal with you in professional life.

 

[dgadee]

And we know how to disable an American nuclear powered aircraft carrier: Covid19

US colleague who has lived in London for years was telling me about his early days as an engineer. He went on a first trip for a new US submarine as non naval and was a bit shocked. The crew stole all the tools and sold them ashore so that there was barely a hammer left. He also said that the officers would not go ashore in case any of the crew attacked and murdered them. I presume this was the 1970s.