Surprisingly non-catastrophic rig failure

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Tim_M
Posts:14
Joined:Sat Nov 28, 2015 10:06 pm
Surprisingly non-catastrophic rig failure

Post by Tim_M » Tue Oct 24, 2017 4:21 am

My whole mast came down while it on a mooring last month, and I thought some people here may be interested in what went wrong. (Spoiler - it's quite easily fixable and there is no damage to mast or hull.)

First of all, I had a very bent turnbuckle because it got twisted as I was raising the mast earlier this year. I was going to get a new part over the winter and replace it in the spring. The other aggravating factor was that my shrouds were a little on the loose side.

The boat was on a mooring at a nearby lake and we had a few windy days - nothing too dramatic - maybe 25-30 knots or so. I went out with the trailer the following week to bring it in for the winter and saw that the mast was down.

So what happened? The bent turnbuckle on the outer shroud broke. Then the spreaders pulled out, letting the inner shrouds go. I'm not entirely sure what failed. The bolt that holds the shroud connector was a little bent, the nut had come off, one of the metal sleeves inside the spreader was missing and the small screw that holds the spreader in place was loose. Neither shroud was connected to the mast. I can't tell in which order these things failed, but the spreaders came apart and the inner shrouds were only held on by the spreaders. The inner shroud tangs were not riveted to the mast.

So then the mast fell over. The mast base plate was badly bent, the pin jammed and the mast base casting was torn like cardboard.

So the good news is that the deck and the mast are both good as new. The mast base, mast step and spreader base can be replaced at reasonable cost. The inner shroud has a few loose wires from it's trauma, so I'll replace that. And I'll replace all 4 shroud turnbuckles - the lower toggle part at least. Oh, and I lost the Windex as well. I might replace that with a no-name version.

So the moral of the story: don't neglect a bent turnbuckle. Not even on small boat on a small lake with no danger of extreme winds.

BadgerJuan
Posts:29
Joined:Thu Sep 20, 2012 3:07 am
Location:Madison Wisconsin

Re: Surprisingly non-catastrophic rig failure

Post by BadgerJuan » Sun Oct 29, 2017 5:19 pm

Interesting story. I moor my boat on Lake Mendoza over the summer and we get some pretty stiff winds that really make the boat bob around. In fact, I was down at the marina several years ago to check on the boat during a wind storm and witnessed another slightly larger boat break it's mooring line and float free!

Still, I would never of imagined that there would be that much force on the shrouds with the sail down, even with the bent turnbuckle.

When I took my boat out a couple of weeks ago, I had a different problem. Everything was going smoothly until I tried to put the boat on the trailer. I found out the keel was not all the way into the hull, even though I couldn't crank it up any further. Turns out that zebra mussels had grown to such an extent within the slot, that the keel wouldn't go up any further. After trying a bunch of tactics, we managed to get it up a bit further. That allowed us to at least balance the boat on the trailer and pull it out of the water. The keel was on the roller, but still not all the way in. Getting in the boat and bouncing worked to fee the keel and allow the boat to settle on the trailer. We could hear the crunch of the shells when that happened.

This is the second year we've had zebra mussels in The lake. They don't stick to bottom paint, so I'm going to try to paint the inside of the keel well before launching in the spring.
Jim Moravec
1979 San Juan 21 MK 2 SN 2270
Madison WI

Condre
Posts:16
Joined:Fri Aug 05, 2016 2:16 am

Re: Surprisingly non-catastrophic rig failure

Post by Condre » Mon Nov 06, 2017 6:08 am

Scary. My mast fell some distance in the fall of 2016 but it wasn't until I started rebedding the deck hardware last summer that I noticed that two chain plates had bent sternward about 45 degrees. Nothing that I was't able to straighten with a big pair of visegrips. Now I think maybe I'll just replace them before I take my boat out again.

cguthrie
Posts:26
Joined:Thu Dec 23, 2010 3:18 pm

Re: Surprisingly non-catastrophic rig failure

Post by cguthrie » Thu Nov 09, 2017 2:28 pm

One other thing to consider is the old brass turn buckles have a lifetime and many of our old boats are reaching it. I had a 45 year old turn buckle fail allowing the mast to fall. It happened to be the forestay turn buckle and happened just as I was putting the boat on the trailer. I had put my hand on the turn buckle to have some place to steady myself as I cranked the boat up onto the trailer the last couple of inches. All of a sudden the mast starts falling backwards and I've still got the turn buckle in my hand. No damage to the mast or step other than the mast head fly. Once I pulled the boat out of the water and could look at what happen, I found the threaded stainless end of the forestay had all the brass threads from the turn buckle still in the threads. This boat had been sailed in salt water during the early part of it's life so that may have contributed.

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