Brian Lawson wrote:
ARE YOU T-R-Y-I-N-G TO **** ALL US SNOW SHOVELERS OFF!!!!!!!
Kidding of course, but no Key West Race Week for me this year either,
so I'm grumpy.
No metallurgist here, but do you think these are OEM? There were
certainly a lot of "stainless steel" screws used that were definitely
NOT marine grade.
OEM, probably yes. Catalina installed them - but it was 20 years ago.
I do take your point, but what is "marine grade"?
Is it anything like "aircraft quality"?
I think the wise thing for something like this is to buy known metals,
not just what's _called_ that.
While I am impressed with how well the photos came out, it's a bit
hard to tell from the pix how far below the surface the thread broke,
The break is about 1/8" above the top of the lock washer.
The deck is about 5/8" thick there.
So it broke just above the inside surface.
but heed the other poster that suggested a bolt that is not full
threaded so it has max strength, and use stainless as a backer. It
also appears that these were standard heads, and not flat-head. That
might put a bit more strain on things too, especially if the stanchion
base has countersunk holes..
The stanchion base plates are not countersunk.
More fastener options there.
Take care.
Brian Lawson,
Bothwell, Ontario.
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On Sat, 29 Jan 2011 20:59:31 -0600, 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