Steel is strong until it’s not
I try to be vigilant and keep an eye on the boat and its systems. The images below illustrate why that’s so important. The first 2 pics are of the bow shackle which connects the starboard leg of our anchor bridle to the boat. Is that just a blemish on the shackle or a crack? Oh, that’s a crack!
I noticed this just moments after we deployed our anchor in Anegada. While having it part would not have been the end of the world, it would have created some unnecessary drama and stress on the windlass, especially if we had been ashore eating lobster when it happened. Good thing I had a large spare shackle which, immediately after this pic was taken, we swapped for the damaged one.
Note that I took the pics before swapping the shackle.
I do have my priorities straight. 🙂
This is NOT my photo but rather one that I had saved on my computer.
THIS definitely would have caused some drama!
This is one reason I don’t like stainless for ground tackle — too susceptible to crevice corrosion (the other being much lower strength than galvanized). After we got our boat we swapped out the last bits of stainless tackle for north-American made high-tensile galvanized items with ratings as high or higher than the chain itself.
As you point out, there is no substitute for regular inspection.
Thanks for sharing this Mike – guess what I’m going to be checking today.
Good luck. 🙂
Thanks Mike…I think. This is a good reminder to check hardware, gear, and rigging for failure and fatigue. But dang it, now I’ve got another task added to my spring launch list!
Thank me if you find something.
a. Does it need to be a bow shackle? I’ve had several crack at that same bend over the years, so I now avoid them when I can. If the load is properly aligned (can’t tesl from the pic) use a D-shackle next time.
b. Is the bridle Amsteel (ignore the rest if it is not)? That can impose terrible impact forces on the system, since chain does not stretch. It is the worst possible material, short of hemp, or chain, and might have contributed to the crack. Alternatives? 3-strand nylon is probably the best bet for fatigue endurance (nylon double braid tends to saw internally under load) and energy absorption, perhaps 1 size smaller than the suggested rode size for your boat. I’m working on some bridle research with another guy but testing will take some time. And don’t expect the bridle to last more than 1-year with daily use; even if it doesn’t break, yours is short and the stretch will go. Additionally, ropes suffer internal damage in this application and tend to fail suddenly.
c. Was the bow shackle rated the same as the chain? It could be a little less on the snubber line, I supose, but not much. The chain is 3/8″ G4 (5400# WLL) and so 3/8-5/8″ shackles–depending on quality–are needed (3500# WLL). It broke simply because it was undersized and the bridle was stiff. The holes is quite large, so I’m guessing someone down-sized it. Sneaky.
A softer bridle and stronger shackles. The forces are certainly MUCH higher on your new ride, so you’ll be building a new expereince base… but you knew that:).
This is all original stuff. I did not change anything on the bridle set up. It does not need to be a box shackle as the one on the other side is a stainless D shackle. I have no idea what they are rated for though. The bridle material looks to be the same as the 12 strand (?) anchor rode.
In general, D shackles are much stronger than bow shackles; that bend is a killer. I’m guessing it leads to metal fatuige, whereas the straight sides of a D shackle are not taking bending stress. I’ve broken several bow shackles, but never a D shackle.
If the bridle is nylon, that all you can do.
I remember you saying that about shackles before. I think I’ll look for some rated D shackles to take the place of the bow shackles.
I’m only looking at a few pictures, so I’m guessing, but….
This was a charter boat. What if the charter guests used the windlass to tension the bridle in the retrieval process, either by accident or because, to them, it seemed like a good way to prevent flopping?
a. The bow shackle has taken a terrible side force.
b. The bridle has been strained near the rupture point, probably many times. Though the windlass is not that powerful, at the moment it drew tight there would be an impact, like a climber falling. I see a popped strand on the bridle.
c. There may be tell tale dents in the aluminum in the hole, from being pulled in and aft.
d. I would check the aluminum clip for cracks.
I know of 2 other cases where attached bridles, like yours, have been destroyed by the windlass or getting crushed under the chain. The sailors were surprised when they suddenly broke under light load, but shouldn’t have been. If I’m right about this, I think you want to replace the bridle.
hmmmm
And loose pins conribute to rigging failures; they don’t spread the load and cracking is the result. A bushing helps.
Today is a big day! I finally have caught up to you and am on the current day’s blog. It took a while to read every post and comment but it has been well worth it. It was also great to be able to meet up with both you and Rebecca at the full moon party. I thought we were going to miss each other. It was quite a surprise to look over and see the two of you standing there!
Our week in the BVI was, as always, way too short. We had another fantastic time. We are looking forward to a family week down there this July.
On another great note, our new boat is due to hit the water any day now. They are actually early. It should be in the BVI sometime in January. If the timing works out right, we may be able to get down there when it arrives and take it out for a week.
Thanks again for the great blog. I have really enjoyed following along. Your journey is very inspirational and I am looking forward to following along as you blaze a new chapter. We hope to see you again in July.
Jay
Congrats, Jay, and thanks. Hope to see you again in July, or even sooner, January perhaps.
We used the same bridle for 20’years before letting it go with the last boat. 1/2″ three strand with galvanized shackles and a galvanized chain hook. Thousands of nights at anchor and no failure. We also put a nylon snubber between the windlass and bridle just in case the bridle where to break. Chances of it happening are slim but that windlass is one expensive item!
Sounds prudent.