Alternative material for rod rigging

[JoBone]

I have learnt a lot from reading the posts already made. Thanks for an interesting forum. I have questions I couldn't find an answer for.

My boat is due for replacement rod rigging and I would like to know if anyone has ever tried using rod and fittings made from a material that has higher corrosion resistance than Nitronic 50 as used by Navtec. I want to improve the installation and to make the rig safer, maybe lighter and hopefully longer lasting without increasing windage. Titanium or duplex stainless or Nickel Chrome alloys should all in theory be possible choices as alternative materials having superior corrosion resistance and meeting the other goals.

I imagine it will be necessary to use a cold reduced bar to give it the necessary strength and such material may be hard to find, but I expect it should be available at least in 2205 stainless as that is pretty commonplace now.

I imagine if titanium were to be used then matching materials would be needed for the tip cups, turbuckles etc and would that be a problem?

Would there be difficulty in cold heading these materials? Would it be allowed under Navtec's agreements?

[Brion Toss]

Hi,
Although I have heard of some attempts at producing alternative rod alloys, including titanium, I don't know of any that have borne fruit. Some alloys -- notably that duplex stainless you mentioned -- do not take well to heading. Others are too trick to extrude, or fatigue too fast. And while I don't have data here showing relative corrosion resistance, Nitronic is near the top in this category, as well as posessing superior strength, etc. So while we can always hope that something even better will come along, I wouldn't hold your breath. If you really want something that performs better, look into extruded Kevlar and the like.
Fair leads,
Brion Toss

[JoBone]

Thanks for that information. I can't understand why no one has tried with titanium. It should give lots of advantages. The duplex steels are stronger and harder to form and need lots of power. 50% more roughly according to spec sheets. Are the heading problems of that nature or are there other problems in forming?

Thanks for the suggestion to look at Kevlar. I hadn't considered it as I heard that costs were out of orbit for various fibres alternatives. Like 4 or 5 times the price of rod and having just now read the Navtec guide it says Kevlar has a requirement to replace at 6 years and to pull test every section, presumably more frequently than 6 years? Looks unattractive. Maybe there are competitive new long lasting carbon or kevlar fibre alternatives?

[Brion Toss]

As Norseman recently discovered, duplex steels do not like being formed: cracking results. And people have, of course, considered titanium, but so far the cost/benefit, plus extrusion issues, make it not feasible.
As for the cost of Kevlar, no question that it, and just about all other forms of synthetic rigging -- other than heat-treated Spectra -- are absurdly expensive/short-lived. But I don't think that is what you asked about.
Fair leads,
Brion Toss

[Coopjammin]

Hi Brian,
Firstly many thanks for producing the rigging handbook I never leave home without it and it's saved my bacon a fews times!

Following on from the thread, I specifically am looking to replace the rod on my 1997 Reichel Pugh 1D48 having done 3 transatlantic crossing in her I am now getting her ready for coding and ultimately day chartering. As such I will need a mast out rig survey and will need some form of work or replacement - under the coding regs this will need carrying out every 5 yrs. as I am on an Atlantic Island will limited rod facilities I am interested in learning more about other options such as dyneema - which presumably could be made up and shipped to me for fitting. What are your thoughts?

Regards

Ian

[Stumble]

I couldn't really see titanium working very well for standing rigging. Well it would work find, but it would be incredibly expensive.

Titanium for all its advantages really hates being cold formed. And requires post forming heat treatment to prevent cracking. But since it will catch fire long before it gets to optimal heat treatment tempratures it has to be heat treated in a noble gass environment. So imagine cold forming the heads then having to bake the entire rod to 1800c in an oven filled with argon.

It could certainlybe done, but carbon fiber would be cheaper, and lighter, and available off the shelf.

The cost of the metal rod that you start with would be pretty cheap by comparison. Probably not much more than normal rod rigging rod.