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Cotter Pins

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.

1.)  Responding to your request:

Yard 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.

During 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.

I 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 money.  Enjoy!

2.)  "In Praise of Cotter Pins"

Before 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 sailors.

The 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.

“Dear Ham:

“With 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:

“Fundamentally, 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 following:

“1. 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.

“2. Cotter pins should be brass, as stainless steel cotter pins are undesirably stiff, therefore difficult to remove and reinstall.

“3. 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.

“4. 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.

“5. 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."

Stephens goes on (if you can believe it) for another three paragraphs, but the above is the meat of his letter on cotter pins.

The 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 than this.

If 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.

Peter