Backstay Cotter Pin

I think I’ve got most of the technical foundations for the website in place now, so the IT-centric blog posts should lighten up!  Thanks for your patience.

This is a post about my new (to me) 1970s Islander 21′.  My first priority, after cleaning the bilge and adding some missing cotter pins, was fixing one rusted and stuck backstay cotter pin.

It’s a pretty small project really, but it’s the first time I’ve mucked about with the stays and shrouds on a sailboat.  And I must say the image of losing control of one of the stays and having a suddenly unbalanced mast is a little nerve wracking to a beginner.  But I gathered a bit of intelligence from folks around the dock, took a deep breath and started work by loosening the turnbuckle and adding a little 3-In-One multi-purpose oil to loosen the clevis pin in its mount.

Luckily my neighbour John (who sounds like one of The Beatles) was very kind and put down his own tools to lend me a hand.  This included helping to secure the mast by attaching the mainsail halyard to one of the aft cleats on the hull.  I find it hard to believe that would be enough support if the aft stay suddenly flew free.  However I never really paid much attention in physics class, I don’t have much experience in these matters, a couple folks suggested it, and it didn’t seem like a terrible idea.  Perhaps the forestay doesn’t exert as much pull on the mast as I’m imagining 🙂

Besides the old cotter pin, I was also interested in looking at this twist at the bottom of the turnbuckle.  I had the boat surveyed by Lachlan of Meadows Marine Surveyors, which included a look at the rigging on deck level, so the plate that attaches the backstay to the hull seems structurally sound.  The only thing my neighbour John suggested was that maybe I slide a few washers into the interior gaps to help the turnbuckle lay flat and still.  But that’s a bigger project for another time.  I didn’t really fancy taking out that clevis pin on my first go!

Rear Stay with a Twist

My main priority in the short term was removing the old rusted cotter pin, because it was breaking apart when I tried to move it with pliers.  I didn’t really get a good close up with my iPad Mini 2, but you can sort of see the absence of a cotter pin in the image below (on the interior side of the bigger clevis pin towards the cockpit).

Old Rusted Rear Stay Cotter Pin

Because of that twist mentioned above, I wasn’t really sure how much the clevis pin would move when I removed the old bit of cotter pin.  I had some foolish visions of the clevis pin popping right out due to tension and the twist in the stay.  But in the end it didn’t move much at all.  I actually had to apply a sort of upward and inward pressure to the turnbuckle and rear stay (wire) to get it to lay flat, which then allowed me to knock the clevis pin in towards the interior of the hull with a rubber mallet (kindly lent to me by John).  Moving the clevis pin inwards finally exposed the cotter pin hole more clearly and let the real work begin.

It took awhile to get a small enough bit of hard metal into the cotter pin hole to clear out the old bit of cotter pin in there.  I think that 3-In-One multi-purpose oil helped a bit with that too.  After that it was a breeze getting the new cotter pin in.  Here it is, felt pretty good!

New Rear Stay Cotter Pin

One unintended consequence of twisting the backstay turnbuckle in some creative ways during the earlier work was this wire got a little frayed.  It’s a short wire of about 1.5′ that goes up from the rear of the boom and clamps onto to the rear stay.  The aft stay wire itself seems fine.

Boom Lift Wire After Twisting the Rear Stay Turnbuckle

I think this short wire provides the same service for the boom as a topping lift or boomkicker…  And I think that service is keeping the boom up when the mainsail is not hoisted…  But I’m going to have to do some more chatting with the folks at Ahoy Sailors meetups in Victoria to be certain about this.  I did see some other boats at Oak Bay Marina with this configuration, and Smithy at Hunter Sailboat Owners also mentions it, so I think it’s somewhat standard.  But when I look at the original photo of an Islander 21′ on a brochure on the sailboat data site this rear boom wire lift isn’t there.  One of my issues is that I don’t seem to have the right search query terms to find out more on the internet. Does anyone know the proper term for this short wire?

Personally I’m not sure I like this extra “noise” on my aft stay, but what do you think?  Since it was near the end of the day I just used some silicone tape (950 psi) to secure the frayed wire.  I didn’t want some gusts to grind through the remaining wire threads and leave my boom swinging around.

Boom Lift Wire Rear Stay – Secured With Silicone Tape

I’m thinking that in the short term I may be able to put a second clamp over the silicone tape and wires, and below the first clamp, and still take it out for a bit of light sailing this summer…

What do you think?

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2 thoughts on “Backstay Cotter Pin”

  1. The cotter ion fix looks great! It’s nice you have a friendly and helpful neighbour. For the frayed cable, I would think it is worrisome that you only have 1 strand of the cable still in the clamp by the looks of it so your suggestion of a second clamp below it sounds like a safe choice until you figure out if it’s needed. Who knows how long the tape will hold up, it depends on how much pressure is on that cable I guess.

  2. Thanks to the advice of Bruce Stott of Gulf Islands Cruising School Ltd. (via Ahoy Sailors on, I added the term “pennant” and “backstay” to my online search queries and got a few more results!

    Here’s one past Islander owner (PaulC19 in 2008) mulling over the same issue that I am here: At that time svHyLyte provided some similar advice to Bruce Stott.

    And Shamwari made note of a similar configuration on an Ericson with a short section of wire from the backstay with a clip on it and the boom was attached to it for support when the sail wasn’t being used

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