P-18 Backstay Lower Split Failure

[Chickenhawk]

Hello All,

I recently returned from a sail on my new-to-me '89 P-18. I happened to notice that my backstay lower split was just about to fail completely. Naturally I lowered the mast and pulled her for the season. I have the replacement part in hand.

When I bought the boat last November the standing rigging was new.

Has anybody else had this problem? Any advice to prevent it?

[tjspiel]

I'm guessing you're talking about the bridle that's attached to the triangular shaped piece of stainless steel that connects to the back stay and the main sheet.

Yes, last Summer I noticed that there was a broken wire on it and within an hour there were several more broken ones.

I think there's just a lot of stress put on the wires next to the thimble from the twisting caused by pulling on the main sheet.

Maybe your new one one wasn't done well and that accelerated the wear or maybe they replaced all the standing rigging except that bridle.

I had a new one made up but I'm going to replace the bridle with an adjustable back stay. It's on my list of winter projects. Something else I've seen people do is use Dyneema instead of wire for the bridle.

[Chickenhawk]

This is excellent information. Thank you!

[Brian S]

This is a known issue in the Precision boats. If you think about how the bridle attaches to the triangle plate for mainsheet, and then the backstay, sheeting action from mainsheet twists the swaged loop of the bridle and will lead to failure.

This is identified in Tom Scott's "The New Trailer Sailor's
Guide to the Precision 18" book available here: https://www.precisionowners.com/ScottBook.htm This is highly recommended for all Precision owners, and other small boats too.

As I recall, Tom created 2 separate bridles for his P-18, one a very long one incorporating a backstay adjuster attached to the backstay, to bend the mast and depower the main, and a separate one for the mainsheet attachment, which may have been done with rope such as Dyneema? The problem with this is that the mainsheet bridle will tend to fall when not tensioned by the main, and I believe this was solved with a length of bungee connecting the backstay to the mainsheet bridle.

[Chickenhawk]

Wow, Brian. That's REALLY helpful! I'm going to look into an adjustable backstay, and as you suggest, Tom Scott's book will be an excellent reference.

Thanks for taking the time to help a noob!

[talbot]

I vote for the adjustable backstay. I use 3/16 Dyneema that terminates in a block. A Dyneema cascade runs from one of the original deck fittings through the block and is tensioned with a Harken triple block attached to the other deck fitting. As someone else mentioned, the main sheet is separate from the backstay on its own traveler, and yes, it uses a short bungee to hold it off  the deck.
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[Chickenhawk]

Really helpful, I picture is just what I needed!

[Riggerdood]

So talbot, am I correct in thinking that the bungee only needs to stretch as far as the traveler goes to each side?

[talbot]

That's correct. My traveller blocks attach to the aft pulpit with soft shackles,so the effective traveller distance is less than the cockpit width. Seems adequate to help with light air sail shape. Otherwise I keep the main sheet amidship. The bungee is just tight enough to keep the main block from hitting the tiller when the sheet is slack.

[Brian S]

So talbot, am I correct in thinking that the bungee only needs to stretch as far as the traveler goes to each side?

You could do this without making it an adjustable traveler, for those who aren't string pullers. In which case the bungee just prevents the mainsheet tackle from falling down into the cockpit.

[Riggerdood]

So talbot, am I correct in thinking that the bungee only needs to stretch as far as the traveler goes to each side?

You could do this without making it an adjustable traveler, for those who aren't string pullers. In which case the bungee just prevents the mainsheet tackle from falling down into the cockpit.

Brian, I don't currently have a traveler on my RS22, but the mainsheet block connection is far enough above the tiller that it doesn't fall down and hit it. As you say though, still a good idea on boats that have that issue, traveler or not.