Testing stainless steel fittings?

[dave_gibsea]

I have taken off my rudder (transom hung) along with its stainless steel fittings plus the V-bolts which attach the rigging through the deck. They all look to be in very good condition despite their age (28 years). The rudder fitting to the skeg is going to be a bespoke item as the builder (Gib'sea) is long gone also, the V bolts for the rigging seem to be an odd size (47mm). Initial thoughts were to replace everything anyway but as they look so good and this option now looks to be an expensive/bespoke option. There is no evidence of pitting/corrosion. The V-bolts are M8 stainless and look like new.

Is it possible to get these items checked/tested somehow? - would a visual check from a surveyor be worthwhile?

Thanks, Dave

 

[vyv_cox]

First establish what you are looking for. The possible failure modes are fatigue, corrosion, overload (either in bending or a straight line). Close visual inspection will find all of these.

Fatigue - cracks, particularly where there are changes of section, thread roots, wear scars and the like. Examine carefully with a glass for any sign of these.
Corrosion - mostly pits, which are also visible, even by eye. Pits can also be initiation sites for fatigue cracks, so if there are any examine carefully.
Overload - should be obvious if bent. Straight line overload would cause some necking or at least extended length. Compare all of them with each other.

Don't be confused by opinions about fatigue life. The figures quoted for rigging life, if any actually exist, are based upon statistical data and take into account all the errors that might befall rigs, like collisions, undertightening, storms, owner stupidity, etc. etc. Close visual inspection is what a professional NDT expert would do, perhaps in some cases supplemented by dye penetrant or other crack detection methods. In your case these are not relevant.

 

[William_H]

Like Viv says visual inspection would be OK. SS metal fittings often tend to be much stronger than needed so not susceptible to failure athough you should examine welding closely. SS wire failure is a different story as it is usually only just strong enough for the job and being strands is susceptible to moisture ingress and fatigue causing failure. (actually I don't know why SS wire failsbut experience shows it does) olewill

 

[dave_gibsea]

Thanks for those thoughts, most helpful. My rigging is 6mm (changed 8 years ago) the bolts are 8mm so I think we have a good set-up. Nice to have peace of mind when you find more wind than was forecast!