Lewmar Syncro block failures, a potential major hazzard

[Pegasus SVYC]

Just a quick heads up about a lewmar syncro 90 block SWL 2000KG which we were using as part of our running rigging, This block basically pulled the Lewmar schackle through the end SS pin. We only had minimal pressure on this block at the time and it has never been super loaded to the design specs or even 1/3 of it. Clearly there was some manufacturing fault in the stainless steel. After much to and fro about this through the lewmar agent, Lewmar's response was

"the head pin has been worn through by possible vibration of the rigging or some other means"

so beware....They clearly don't care about their clients and if you have Lewmar blocks you may want to inspect them on a regular basis. This is an accident waiting to happen and I am amazed that Lewmar are not interested.

Photos of the failure can be found here.

https://picasaweb.google.com/103419419518034555314/BrokenLewmarBlockPegasusDec2012?authuser=0&authkey =Gv1sRgCIiC4OrOpN3tOw&feat=directlink

[Matt Johnson]

Yikes! I have 6 of the syncro blocks for my three sets of reefs (they were cheap). Scary to think what would happen if that failed when I was using the third reef. Guess this is way we should always tie in the reef once we get it down.

I'll be getting Garhauer blocks to replace these soon.

[44'cruisingcat]

Made me check mine. They all look perfect. There must have been some flaw in the steel, I've loaded some of mine pretty highly - broken a 12mm double braid headsail sheet a couple of times.

Dissapointing response from Lewmar.

[Stumble]

Pegasus,

It doesn't look like a defect to me. The damage I am seeing looks like pretty standard corrosion on stainless steel exposed to salt water. Unless the parts are less than a year old I don't see anything that lewmar is responsible for. This is just a good example of why stainless steel is being replaced by titanium.

[Jim Cate]

Originally Posted by Stumble

Pegasus,

It doesn't look like a defect to me. The damage I am seeing looks like pretty standard corrosion on stainless steel exposed to salt water. Unless the parts are less than a year old I don't see anything that lewmar is responsible for. This is just a good example of why stainless steel is being replaced by titanium.

G'Day Pegasus,

I gotta agree with Greg here: that looks like a classic case of crevice corrosion to me. Brown stains, other propagating cracks, no sign of wear.

I do not know what alloy they use (or claim to use) but many mfg's use the more machinable s/s alloys in such applications, and these don't have very good corrosion resistance.

I'm always leery when I see brown stains around such s/s fittings. It always means something bad is going on chemically.

As it happens, I have a similar fiddle block in my backstay tensioner. I'm about to step out into the cockpit and have a look at mine. Thanks for the heads up!

Cheers,

Jim

[Stumble]

I could be wrong, but I seem to remember that lewmar uses 304 stainless for strength on the pins. Even at low loads those shoulders and pin holes carry pretty serious compression loads on a psi basis. Sadly this results in a slightly higher rate of corrosion than in 316, but since 316 isn't strong enough to handle the loads at the required size there aren't many options.