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Old 11-08-2015, 15:01   #31
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Re: How often does a cleat snap?

Quote:
Originally Posted by micah719 View Post
Which loading would be worse: surge at a dock or a tow in rough water?
For towing I wrap around the Mast, never a cleat.
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Old 11-08-2015, 17:49   #32
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Re: How often does a cleat snap?

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Originally Posted by thinwater View Post
I would add to the OP's question, is anyone aware of any strength testing data? It seems every other bit of rigging hardware is rated, but not cleats, as though they were unimportant. Always seemed odd.

I did find this:
Foundation Findings #16 [Cleats]
Though it only lists very small cleats. The suggestion, of course, is that the mooring cleats on a good sized cat should be ridiculously strong.

The other questions, of course...
* What was the material of the cleat?
* Design of cleat?
* How was it cleated?
*What was the material of the line?
* How long was the line?
* Were the bow lines from the dock side or the seaward side?

The forces on mooring lines can be many tons when the boat starts dancing; I've seen a lot of failures on boats tied up along side during even short squalls, and not due to chafe, just extreme stress. It all depends on wind direction, leverage, waves, and where the fenders are placed.
One other question to consider: was the line diameter too large so that a very large bending force may have been applied forcing the ear of the cleat up? Most boat cleats are aluminum and way stronger than the bolts normally used to secure them.
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Old 11-08-2015, 18:16   #33
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Re: How often does a cleat snap?

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Originally Posted by adlib2 View Post
For towing I wrap around the Mast, never a cleat.
You must be kidding right?

I had one snap the bolts due to me tying it at an improper but necessary angle at the time. Lots of people use sailing lines instead of mooring lines which cause too much stress.
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Old 11-08-2015, 18:31   #34
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Re: How often does a cleat snap?

A couple of years ago I was hacking off an old bow sprit. Wacking it pretty good with a hammer. I nicked a nearby cast cleat and DINK it split in two. One horn flying across the deck. It was only a glancing blow, I was shocked to see it fail so easily.

I'm not sure of the material, some kind of cast that had been welded to the deck.

I replaced it and its twin with a SS cleat, again welded to the deck.
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Old 11-08-2015, 18:32   #35
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Re: How often does a cleat snap?

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Originally Posted by sakemoment View Post
Hello fellow CF community. I have enjoyed perusing the forums for quite some time however this is my first post.

Bit of background: We purchased a 2010 ex-charter 38' Leopard Sailing Catamaran in Croatia back in December of 2014 and moved aboard with a just-turned 4-year-old and a shiny new 3-month-old to begin our sailing adventure.

Last night we were caught by surprise as a strong bora came through (even though there was no such wind in the forecast) - we are protected from N and E winds but S and W winds can make things uncomfortable and push us up against the dock.

Long story short, we were docked on our port side, with spring lines, bow and mid-ship lines all cleated off. Without warning the port stern cleat snapped in half and dislodged from the boat causing some damage to the fiberglass and gel coat. My question for this very knowledgeable and experienced group is - how common is it for a cleat to literally snap in two? The boat is only 5 years old, has been impeccably maintained and we're now wondering if we ought to have the rest of the cleats checked and/or replaced or whether this was just a bit of a freak occurrence?

Thanks for your input.
There are several failure mechanisms.

Brittle fracture either through overloading, a latent defect or a combination. Inspection of the broken pieces under low power magnification will often be detectable.

High cycle fatigue is rarely a failure mode a cleat will experience. Think many millions of alternating load cycles.

Low cycle fatigue is a more feasible failure mode. As little as 1000 cycles at a sufficiently high alternating load could lead to failure.

Material quality is likely the root cause in the causal chain if loads have been sufficiently low. A lack of toughness, less than the design minimum, is common. Toughness is the ability to absorb energy and is the key design and quality control characteristic you want in a cleat.

The fatigue failure load is likely to be much less than the ultimate tensile strength.

If the cleat is deformed then overloading above the yield strength is likely. This will be visible.

Long spring lines should carry most of the load. Short bow and stern lines can induce much higher load acceleration leading to a high strain, not stress, loading. Low cycle fatigue failures are usually strain related.

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Old 11-08-2015, 18:47   #36
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Re: How often does a cleat snap?

I used to own a 38' spray replica on the Bohemia river in md. We were on the bulkhead and boat wakes ran into the marina bounced off the seawall and hit her from both Directtions almost at the same time.

Springs took the front back motion but side to side was also an issue. Dock layout prevented stern lines more than 8' long.

At 12 tons the forces were pretty strong and the stress started making the bolt holes oval shaped so the cleats would move around. Not good.

After fixing the bolt holes we put rubber snubbers in the short dock lines. They worked great. When a hurrican storm surge raised the water 5' over normal hightide the snubbers broke releasing the extra line and saved our cleats.

Reccomend them without reservation.

Jfyiii
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Old 11-08-2015, 19:11   #37
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Re: How often does a cleat snap?

Quote:
Originally Posted by sakemoment View Post
Long story short, we were docked on our port side, with spring lines, bow and mid-ship lines all cleated off. Without warning the port stern cleat snapped in half and dislodged from the boat causing some damage to the fiberglass and gel coat. My question for this very knowledgeable and experienced group is - how common is it for a cleat to literally snap in two? The boat is only 5 years old, has been impeccably maintained and we're now wondering if we ought to have the rest of the cleats checked and/or replaced or whether this was just a bit of a freak occurrence?
It is not common for a cleat to snap in two. More so, it's not at all normal. When stressed, cleats should deform.

This small thing is to be taken seriously, thus: Take the cleat to a metallurgist and ask him why it failed. Maybe he'll say it's a "cold shut", meaning the molten metal was cool and did not fuse when it came around in the mold. Certainly he can tell you what to look for to check your other cleats.
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Old 11-08-2015, 21:41   #38
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Re: How often does a cleat snap?

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Originally Posted by nelsmay View Post
I sharted running my docking lines through the chock, across my bow to opposite side cleats. Less of a turn for the spring line back to the midship cleat on the dock. I believe it helps reduce the load on the chock somewhat.
Be very careful with this. The extra distance between the chock and cleat will cause more chafe at the chock - learned the hard way. Assuming your line has a reasonable amount of (desirable) stretch, if the distance from cleat to chock is increased from 6" to 6' the movement of the line in the chock will increase twelve-fold. It can tear up a line in short order.

The old rule of thumb for the length of a cleat is 2" for every 1/8" of rope diameter. So a 10" cleat is for 5/8" line. Many production boats use undersize cleats.

Greg
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Old 11-08-2015, 22:12   #39
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Re: How often does a cleat snap?

Hi folks
Also a mooring rope should specific reference.
The rope should be proper thickness and elastic to absorb the load softly.
Ilan
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Old 11-08-2015, 23:55   #40
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Re: How often does a cleat snap?

According to Snopes.com, on December 24, 1998, a rope used to secure the sailing ship Columbia as it docked tore loose the metal cleat to which it was attached. The cleat sailed through the air and struck the heads of two guests who were waiting to board the ship. One died. This was the first Disneyland guest death not attributable to any negligence on the part of the guest. It was attributed to a combination of insufficiently rigorous ride maintenance and an insufficiently experienced supervisor's assuming an attraction operator's role.
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Old 12-08-2015, 00:20   #41
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Re: How often does a cleat snap?

So, I'm learning here.

Thinwater asked why not midship cleat for my spring line? Yes, better for sure I think. Wish I had thought of that. Should spring lines generally cleat amidships? From an aft piling to a midship cleat in this case. And I agree about the greater force at the dock vs anchor.

nelsmay mentions the 180 turn around the chock acting as a pulley and increasing the force. I thought about this at the time some, but couldn't muster enough conscious brain cells to decide anything.

Crossings lines to opposite side cleats causes an upward angle. My cleats are on an angled surface that runs from the bow a few feet.

Beausoeil, some people got names of the waking boats, dockmaster was no help though not sure he is supposed to be. Never heard much after except people complaining. A dockmate stands at the outside dock and blasts an air horn often.
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Old 12-08-2015, 00:33   #42
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Re: How often does a cleat snap?

Quote:
Originally Posted by micah719 View Post
Which loading would be worse: surge at a dock or a tow in rough water?
I certainly wouldn't want tow your boat with mine in rough water.

Two equal weight boats could snatch harder than a piling/boat combo maybe? Because wave action could accelerate them in opposite directions. Maybe so.
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Old 12-08-2015, 08:15   #43
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Re: How often does a cleat snap?

GordMay and noelex 77 - Thank-you for the warm welcome to the forum and thanks to all who responded to my post.

After reading all posts we decided that the reason the cleat snapped was very much in line with comments posted here by GrahamHo, hamburking and deblen.

We have 15 and 20 meter docking/mooring lines (not sail lines - see pics) however we agree that the angle to which we had the lines running from the cleat to the dock did not allow sufficient "give" for the lines to run and let the boat "dance" in the rough weather, the constant jolting eventually was just too much pressure for the stern cleat to handle. I will say that I don't believe it was the backing plate that failed. I'm sure you'll agree when you see the pictures.

Having small children to get on and off the boat we didn't run the lines too far down the dock to avoid too having them get in the way of getting on and off the boat, so they were attached to a closer dock cleat which rendered the angle at which the line ran from cleat to dock at close to 90 degrees (though there was a good amount of slack in the line (to the point where we had to pull on the lines to bring the boat closer to dock to assist kiddos getting on and off). Obviously the wind/wave force strained the line excessively.

thinwater - to answer some of your questions:
* What was the material of the cleat? Looks to be a combination of aluminum and other elements.
* Design of cleat? open-base cleat.
* How was it cleated? figure-eight on cleat, looped around dock cleat and cleated off back at the stern cleat again.
*What was the material of the line? nylon lines
* How long was the line? 20 meters.
* Were the bow lines from the dock side or the seaward side? Bow line was from the dock side, and we had a spring on both bow and stern also.

Nicholson58 - thank-you for your insight - we're definitely keen to get the cleat checked out so we can see whether or not it is a universal issue that will affect all of the others.

We are young sailors, learning new things each day, and we've learned a good lesson here. One of the marineros who was assisting us with the boat was whacked in the face when the line whipped up from the snapped cleat so we owe those guys a few beers. Otherwise (fortunately) no real harm done.
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Old 12-08-2015, 15:34   #44
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Re: How often does a cleat snap?

Now this appeals to me....though a car tyre might also work.

Shock absorber / for mooring / for docks - M2/M3 - INMARE - Videos

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Old 14-08-2015, 05:36   #45
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Re: How often does a cleat snap?

………………………………………………………...Some years back, ,a boat ran aground on a jetty wall that submerges at high tide here in Kingston. A fellow boater tried to pull him off…..cleat pulled out from deck( of towing boat) and stored energy in the nylon towing line fired the loose cleat back into the brain of the captain killing him instantly.
Somewhat off topic,but it is easy to underestimate many of the forces involved when any system is under strain.
Lest any here consider the above tragedy an anomaly,there have been many cases of community tug of wars at church picnics etc. where many in the large participating crowd
were seriously injured when the nylon rope parted . One case in the midwest , a number of young children lost some fingers while participating in an adult tug of war.
Hard to believe, but just take a large elastic band and pull to breaking and you will be painfully convinced. .

……………………………………luv you all………………….mike…………………………………………………………………………………………… .
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