How often does a cleat snap?

[sakemoment]

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.

[thinwater]

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:
http://www.boatus.org/findings/16/
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.

[four winds]

These of course are chocks, leading lines to inboard cleats.

Original aluminum on starboard side and a replacement steel chock on port. Couldn't find original.

Wakes from the ICW constantly entered my old marina but it took two years for conditions severe enough to snap the original aluminum port chock in half. Right down the middle.

[GordMay]

Greetings and welcome aboard the CF, Sakemoment.

IME, cleats seldom break; but more often separate from the deck, due to inadequate backing plates..

[DeepFrz]

Do a google custom search of the site on "broken cleats". Surprising number of threads come up and many of them are due to deck structural failure, but not all.

[barnakiel]

Poor backing or laminate deterioration under the cleat will cause a fail too. GRP deterioration under cleats is quite common due to water ingress.

On a sound boat with good equipment cleats hardly ever snap.

b.

[noelex 77]

Welcome to the forum.

This is something that should never happen. It is not hard to engineer a strong cleat. Sadly, under strength cleats are quite common.

Unfortunately the loss of the line often results in significant other damage so take heart that the result was not worse, for example a bashed in stern.

The most common problem is usually inadequate backing plates and laminate strength. So the cleat does not break, but pulls out. It is easier to reinforce the cleat before damage occurs. Have a close look at the other cleats, especially those under high load such as attachment points used for anchoring, drogues or being dragged off a sandbar for example. They are usually not expensive or difficult to make significantly stronger and it is a pity this is not done at the build stage.

[jheldatksuedu]

All materials are different, some fail by fatigue, some fail due to corrosion, some fail by bending, some just take the load until they snap. Most objects are designed to withstand 2-3 times the design load and last a long time in normal service but eventually may fail sue to combination of all the above factors. This is what mechanical engineering is all about, making trade off decisions on application, cost and life expectancy.

[hamburking]

I have seen this several times at my marina...always the same cause...short dock lines.

Dock lines must be LONG LINES.

A long dock line allows the boat to travel up and down on waves (or wakes) without pulling on the line. Also, a long line is a good "spring", it can absorb and release energy smoothly, without damage.

I recall the most recent time when a power boat had broken both its bow and stern cleats and was somewhat adrift. I helped the owner get the boat back to the dock, where he asked..."now what do I tie my dock line to on the boat?" I suggested he turn the boat around and use the cleats on the other side, to which he replied "Those broke off last time".

A quick walk around my marina and I can find lots of boats with docklines which are almost cleat to bollard, less than 2' of line. This creates huge stresses, totally unecessarily.

[msrcal36]

I agree regarding backing plates, a MUST to spread the potentially huge load. Deck cleats (oversized) of bronze or stainless steel are my answer. On our Cal 36 (12,000 lbs) I installed 10 inch ss Herrshoff by Bosun Supplies: Stainless Steel Blue Water Cleat | Bosun Supplies. Our Moody 42 PH ketch (25,000 lbs) was equipped with 12 inch bronze. I look at deck cleats and ask what is the worst it can take then go one size bigger. Dock line should fail before my cleat does. $0.02

[msrcal36]

12" bronze cleat

[msrcal36]

G 10 fiberglass is the best choice for backing plates. No dry rot, 0% compression and very easy to work with. G10 Fiberglass Board

[Rapanui]

Itvis extremely difficult to break a cleat if the load is parallel to the deck. However, more and more and especially on cats the cleats are fitted on an incline so the load is inclined vertically to the long axis of the cleat which imposes bending loads on the cleat and reports of failures. Similarly, even if the cleat is fitted horizontally, if there is a lot of rope on the cleat and the load is applied obliquely in the horizontal plane then the cleat can twist and break. Thats what fairleads are designed to obviate

[meirriba]

Snubbers on the lines between bollard and cleat will dampen the shock loads.
Check backing underneath for soft GRP (water ingress -> delamination/osmosis).

[four winds]

To add to my post #3.

It was a 15 foot spring line secured to a piling alongside amidship that snapped my chock.

A parade of tournament sportfishers (50-70 footers) blasted past the docks about 50' off that wrecked havoc on the docks and boats. Probably more than a dozen boats suffered damage. Plus a few pilings snapped or were pulled free.

As far as I know, not a single captain took responsibility for their wake damage.