Tuesday, November 6, 2018

The story of my inner forestay failure and repair


Short version the fitting between the threaded Norsemen and the overcenter lever failed and I got a similar fitting and adapted it to fit

Long version.

We were sailing up to Guadeloupe from the Saintes on a fairly boisterous day. Just off the Southern tip of the high island the wind speed increased which I was expecting because of the compression and the seas got a bit higher and definitely more confused. I was bot worried as I had been in similar conditions before and had had the rigging professionally inspected by a rigger 3 months ago. There was a big bang, the boat lurched and the staysail luff developed a large belly. We were a 100 yards from getting into the lee of Guadeloupe so I just kept going but let out the staysail sheet a bit. In the lee I dropped the sail and rolled some genoa.

We dropped the hook at Anse La Barque and had a look. The forestay terminates at the bottom in a male thread Norseman. With a female threaded eye which attached the forestay to the overcenter lever.
It was obvious that the head of the eye fitting had come off the stem. There was clear evidence of corrosion at the break with only a little ring of bright metal near the surface. So it looks like it has corroded from the inside out. My inspection also came up with three cracks in the head. All of this should have been spotted by me and certainly I feel the expensive 'expert' should have found them

Anyway I need a new one. Calipers and thread gauges establish that it is a 7/16th UNF thread and the eye diameter is 9/16ths.

A search on the internet comes up empty. I post some forum queries with pics and go to bed thinking that someone somewhere will know where I can get a new one.

On the internet no one has come up with a definitive answer but a couple of people suggest that it might be a swage end. We drive over tp Pointe a Pitre and visit the rigger and other machine shops. Now they talk metric here and I am somewhat sanguine about my chances of getting an oddbal Imperial fitting but it is a nice day for a drive and we will stop off and do the tourist rain forest things on the way back.
We come away with this fitting The hole in the stem is too large but it should swage down to the correct ID for tapping 7/16 UNF the eye is very close to 9/16th. None of the fittings that could have been tapped 7/16th had a large enough eye. He could not swage it down for me as his machine was broken and no one else had one.

So no worries Antigua is the next island and they have a good rigging shop there.

We sail up to Antigua and go visit the rigging shop. Now I have been cruising the Caribbean for 15 years now and always found the engineering shops to be very knowledgeable resourceful and willing to help out in any way possible to get you back sailing. I was surprised to find disinterested staff who did not see how to help me and told me to wait and see the boss. When I eventually got to speak with the boss he said that he had not seen an overcenter lever like mine for 25 years had nothing that would fit and he would not use his machine to swage down my new fitting.

No big deal I thought as I was due to fly out to Salt Lake City for my annual holiday off the boat to go skiing. Someone in Salt Lake City will sort me out. On arrival I got the Yellow pages out and went looking for an engineering shop with a metric swaging machine or at least an imperial one that might do the job. Nope nobody could swage that size.

It was time for some lateral thinking. I had grown up with blacksmiths shoeing my sisters horses and had recently seen how a blacksmith using just a hammer anvil and forge could turn a piece of flat bar into a gunbarrel [seen on youtube]

https://youtu.be/qTy3uQFsirk

so as my new eye had to be malleable perhaps a smith could reduce it down to the point I could get it tapped to the size I needed.

The first two I spoke to only did decorative scrolls but then I found a real blacksmith Matt Danielson at Wasatch Forge Initially he was somewhat reluctant as he said stainless was often brittle and would crack when forged. I said I thought this piece would be malleable as it had to flow when swaged He agreed to have a look at it and maybe give a go and we arranged a time. He looks like a smith and must be around 6' 6”. He decided it did not look brittle and when I said if it breaks or cracks so be it I would not hold him responsible in any way. So he got the forge up to forging heat and started.
The blacksmith's motto is “ Get it hot. Hit it hard “
I was expecting him to use a blacksmiths swaging block but he worked just on the anvil. Over and over he bought it up to a bright cherry red took it to the anvil and pounded on it. It took 40 minutes but when he was done the 3/8th mandrel would slide in and the exterior was round and showed almost kn evidence of hammer marks. It was black from the forge but he soon polished it up on a sander. He said that while he could hand tap it at the forge I should take it to a machine shop he used as they could machine tap it with a much smaller risk of breaking the tap and scrapping the piece.

The machine shop did a good job with a nice clean thread and I set it aside and went skiing.
Back on the boat I tried it on the thread and it ran on smoothly. It needed a little filing to fit the overcenter lever but we are back in business.

1 comment:

  1. So pleased that you were able to have it fixed! I really enjoy the blog....the next best thing to being there.
    Gaye

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