Forestay Cotter Pin Maintenance

[theway]

I climbed the mast for an inspection and found this! Clevis pin pulling out the cotter pin which connects the forestay to the masthead.




I'm not sure how old it is but it looks like it would eventually give out. So I figure I'd post this to worry everyone else and see what you think. I'd like to see some kind of back up, like a lock nut on the end of the clevis pin.

I did replace the cotter pin, and will keep a closer eye on it. (I think it's a bit thicker)

[GordMay]

The clevis pin looks to be too long for the tang forks. Install penny washers outside of forks (or replace pin).

[theway]

Originally Posted by GordMay

The clevis pin looks to be too long for the tang forks. Install penny washers outside of forks (or replace pin).

Thanks for the tip, but how does a shorter pin or washers prevent this from happening over time?

[Pauls]

A shorter pin will not change the dynamics of the situation. If there is significant clearance between the pin and the hole it is fitted in then installing a washer which is a close fit on the pin diameter will help. A thicker, stronger cotter pin is definitely an improvement. If necessary, drill out the existing pin hole to enable using a larger diameter cotter.

[Cheechako]

I'd put the cotter pin on the outside away from the lines.
Those are some good pictures to save showing why not to paint your mast for those who enquire here on the forum. That's way up top, which is often better than the lower 8 ft or so!

[model 10]

Also the tails of a cotter pin on a sailboat should be bent only 30deg (Olin Stephens maybe).

[um saudade]

If you were to pull the stay and inspect the mast tang you would find it worn in an elongated and angled hole. That, combined with wear on the pin, is the reason the pin is pulling sideways, it’s transferring some of the downward force outward and in the process trying to pull the cotter key through the hole with it as it goes.

You may get a better angle on the rigging pin ( a new pin) by reversing it in the hole ( pin head to port rather than starboard) so the head wants to pull inward rather than outboard. If the tang is really worn (and I suspect it is) I would feel better with a bolt and double nuts (or aircraft nut) rather than a pin and key.

The cotter key is not meant to take any appreciable stress. And it won’t. They are very soft steel made to be easily bent and is already weak because it is a split pin, not nearly as strong as a comparable solid pin of the same metal.

[barnakiel]

Originally Posted by Guy

Also the tails of a cotter pin on a sailboat should be bent only 30deg (Olin Stephens maybe).

Why?

barnakiel

[Suijin]

Originally Posted by Pauls

A shorter pin will not change the dynamics of the situation. If there is significant clearance between the pin and the hole it is fitted in then installing a washer which is a close fit on the pin diameter will help.

If a washer will help, then a shorter pin will help. It amounts to the same thing.

Clevis pins that are too long will "walk" and cause wear over time and eventually try and walk out, like this one is doing. If they are properly sized they are more secure and subject to less wear and failure.

I would start with a properly sized clevis pin. If this is an area that you inspect once a season you can see how it fares and whether you need to pursue a different solution.

[barnakiel]

I have seen reversing the pin changing the situation. I have also seen using a new pin change the situation. I am not sure why.

In our boat I tape it round. Seems to work.

b.

[theway]

Originally Posted by Guy

Also the tails of a cotter pin on a sailboat should be bent only 30deg (Olin Stephens maybe).

Yeah, I've read that article that gets circulated about how much to bend them, but I couldn't get the pin in the other way (head on top) so I felt much better having the tails bent more than 30deg

[Sailmonkey]

Hell, I bend the ends of the pin into a loop so they can't snag anything!

[theway]

Originally Posted by um saudade

If you were to pull the stay and inspect the mast tang you would find it worn in an elongated and angled hole. That, combined with wear on the pin, is the reason the pin is pulling sideways, it’s transferring some of the downward force outward and in the process trying to pull the cotter key through the hole with it as it goes.



You may get a better angle on the rigging pin ( a new pin) by reversing it in the hole ( pin head to port rather than starboard) so the head wants to pull inward rather than outboard. If the tang is really worn (and I suspect it is) I would feel better with a bolt and double nuts (or aircraft nut) rather than a pin and key.



The cotter key is not meant to take any appreciable stress. And it won’t. They are very soft steel made to be easily bent and is already weak because it is a split pin, not nearly as strong as a comparable solid pin of the same metal.

Thanks for the info, I'll install a solid pin the next time I'm up there. And when I get to Australia I'll find something with double nuts.

[theway]

Originally Posted by barnakiel

I have seen reversing the pin changing the situation. I have also seen using a new pin change the situation. I am not sure why.

In our boat I tape it round. Seems to work.

b.

I'll definitely add tape the next time. But hopefully I'll have a bolt with locking nuts to install.

[theway]

For future reference... What would be the process for replacing the clevis pin so that the forestay or mast doesn't fall to the ground? Spare Halyard to a strong point forward, or would a crane be needed?

(Pearson 323 is keel stepped)