s/v Nordic Song
Thanks to Peter for this good information on the correct use of cotter pins. Peter sent me this after a discussion on the Pearson message board. For more information on cotter pins follow this link.
to your request:
crews love to take new, long cotter pins and wrap them back over the
fitting (clevis) pin, or even around turnbuckle bodies, rendering the
cotter pins difficult to remove and useless for later refitting.
the refit of Canto I took all our clevis pins and lightly
countersunk their cotter pin hole ends on a drill press. I also bought a
supply of (alas) stainless cotter pins and trimmed them as suggested,
rounding the ends of their legs. During the stepping of the mast I
worked with the yard crew and got them to open the legs of the cotter
pins only about 15o each. It was pretty funny to watch, as
they clearly felt very uncomfortable doing this rather than wrapping the
long legs of the cotter pins back around the turnbuckles. I then
used a section of PVC pipe as a turnbuckle boot.
have no problem buying new cotter pins, if need be, each time the mast
is to be stepped. But the possibility of being able to quickly remove
cotter pins should be attractive to every commercial yard, as time is
Praise of Cotter Pins "
its publishers discovered the rarified air of the super mega yacht and
the emergence of the many specialized sailing magazines, “Yachting”
magazine was a real haven for the sailor and was staffed with many fine
following is a letter submitted to “Yachting” over 40 (maybe over
50) years ago by Rod Stephens, Jr. Rod was the “quiet” brother and
partner of Olin Stephens, of Sparkman and Stephens fame. Rod was
responsible for the design of the rigging of the boats that came out of
that famous shop, as well as guiding the construction of the shop’s
custom and production yacht designs.
regard to the much-maligned cotter pin, perhaps it would be of interest
and of service to your readers to make note of the following points:
the cotter pin, when properly used, is the best and safest method of
locking pitting pins, turnbuckles, etc. in a yacht’s rigging. However
they are often misused, making them unpleasant and causing people to try
hard to find other ways of doing the job. Rather than doing this, I
would suggest that they use the cotter pins properly, taking note of the
Each end of each cotter pin must be carefully filed so that it is
absolutely smooth so that a magnifying glass would show a more-or-less
hemispherical end. This makes the cotter pin less apt to cause damage,
easier to open, and easier to tape or otherwise protect.
Cotter pins should be brass, as stainless steel cotter pins are
undesirably stiff, therefore difficult to remove and reinstall.
Cotter pin holes in the fitting pins they are intended to secure must
have a bit of clearance, including a slight countersink at each end.
Otherwise, a hole that is a close fit, and without a countersink, makes
it difficult to remove a cotter pin and almost impossible to reinstall
it. On the other hand, a hole that is too sloppy makes the cotter pin
less certain to do its important job.
The length of each cotter pin should be carefully controlled. It should
protrude not less than 50% nor more than 60% of the diameter of the
fitting pin in which it is installed. The only exception is where pins
are in and out frequently, in which case they should properly extend
100% of the shaft diameter.
Cotter pins must be opened carefully, each leg approximately 15o
making a total spread of 30 o between the two legs. With this
opening, the cotter pin is not weakened by sharp bending and can easily
be removed, as when adjusting turnbuckles. There are, however, two
exceptions – in the case of high velocity machinery certainly the
normal practice of opening the pin right back would be accepted but this
would generally be with steel pins."
goes on (if you can believe it) for another three paragraphs, but the
above is the meat of his letter on cotter pins.
attached computer file is a copy of the complete article, together with
the chart and a couple of illustrations. If you can open this file you
should be able to print the whole article on one page. Sorry, I'm not
good at manipulating computer files to the point were I can do better
you cannot open the attached file, please get back to me. By that time I
will have transcribed the rest of the article and the table into a
text file. But work on it a little, as the whole article is better. Or
maybe one of you can post the whole article on a web site where everyone
can benefit from the fine artwork of Ham deFontaine.