On Jan 29, 7:59*pm, CaveLamb wrote:
I snapped a stanchion bolt the other day!
1/4" stainless steel machine screw actually.

Starboard stanchion by the cockpit. Forward inboard bolt.
The stanchions get abused sometimes, people grabbing them or the lifelines
while docking. *This one was leaning forward an inch off of vertical, but seemed
sturdy enough.

I had the lifelines loose and was pulling on it (aft) - not all that hard!
to straighten it up - And something went POP! Pretty loud too

Inspecting it, it was pretty obvious what had happened, so I
dug the bolt out and replaced it.

This bolt (machine screw actually) had some serious corrosion issues.
(See the attached photos)

There is quite a bit of old damage on the mating surfaces.
That's the dull gray part.
And quite a bit of sealant over the old damage!

The bright metal tab seems to be the place where it broke.
There was NOT A LOT of metal there!

I have recently learned that there is an aluminum plate buried in the
deck lay-up where the stanchions are attached.

What say ye? *Was this 20 years of dissimilar metal corrosion?
(4 photos)http://www.home.earthlink.net/~capri26/bolt.htm

As soon as possible, ALL of the stanchions are going to be pulled and
re-bedded.

--

Richard Lamb
email me:
web site: *http://www.home.earthlink.net/~cavelamb

The aluminum would be the loser if it was electrolytic corrosion.
Probably chloride corrosion. Stainless steel -isn't-, at least when
it comes to sea water. You get inter-granular corrosion, basically
chunks fall out, how big depends on the alloy's grain structure. And
checking bolts would probably be a good idea, I'm told a beeswax-
pitch mixture makes a good goop for threaded hardware exposed to
seawater. Hope the stub wasn't hard to get out.

Stan