Cleats : BoatUS Foundation

Feet Don’t Fail Me Now!

Foundation Findings #16 – Circa 1990

You’ve heard the expression, “solely as robust as the weakest hyperlink.” And so it is with cleats. Whether you’re utilizing a cleat for docking, mooring, towing a dinghy, or securing a halyard, it’s essential to consider the cleat as only a single a part of an entire system (and never necessarily an important a part of the system).

The whole system consists of the cleat, the fasteners-including nuts, bolts and washers, the deck or other mounting platform, backing plates-and the road. You depend on that system to keep your boat secure, even in situations like storms or towing that topic the system to great stress and marine cleat parts shock masses.

On this test, the BoatUS Foundation needed to examine one of many most critical hyperlinks within the system: cleats. Working in conjunction with the University of Virginia School of Engineering, we arrange laboratory testing apparatus to simulate the masses placed on cleats of different design configurations and materials. Our objective was to find out the path and magnitude of the smallest drive required to deform or break a cleat fastened to a inflexible floor with mounting hardware specified by the manufacturer.

Cleat Types & Failure Loads

Test Procedures

The foundation tested 11 six inch cleats made of nylon, aluminum, marinium (a magnesium-aluminum- titanium-beryllium alloy), chrome-plated zinc, bronze, stainless steel, and Zamac (a high-grade die-solid zinc alloy). Five of the cleats had been two-gap; six have been 4-gap. The cleats have been mounted on a 3/8- 6 inch thick steel plate in a tensile check machine. Admittedly, the steel plate will not be the same as a deck mounting on a boat, but it prevents the fasteners from pulling out, and it eliminates completely different boat decking materials as a variable, in order that only the cleat itself is being tested. To make sure uniformity, the cleats have been mounted to the steel plate using manufacturer beneficial sizes of flathead stainless steel bolts, nuts and washers, all tightened to exactly the identical torque. The tensile energy of the bolts was additionally examined; they fell consistently within the manufacturer-listed vary of 80,000 psi ( +/-10%).

Using a 3/8-inch diameter plastic- coated steel cable around each cleat, we pulled at 4 angles, as shown within the diagram under. (Plastic- coated cable was used to ensure that the cause of a failure would not be the rope or a weak level brought on by wire abrading the cleat.) The first three pulls had been parallel to the bottom, at 0°, 45° and 90° relative to the cleat’s axis. The fourth pull was an upward 45°/45° pull, with the cable around both legs, pulling at 45° vertical and 45° ahead.

The take a look at was carried out underneath strictly managed laboratory conditions. We suspect, nevertheless, that different assessments would possibly produce barely totally different outcomes, as a result of the failure figures in each pull are dependent on so many variables.

For example, the seating of the fasteners relative to the exact heart of the holes within the toes has a direct effect on load distribution and consequently the quantity of stress positioned on any given part of the cleat. Similarly, using a larger dimension line might produce totally different results, because larger line exerts more force on the underside of the horn and less on the top of the leg. It is reassuring, nonetheless, that the outcomes of this test coincide in most respects with these of an identical cleat check performed by a producer several years ago.

Test Results

The cleat assemblies withstood simple tension a great deal of between 1,190 and 7,500 lbs. before a failure occurred. The lower figure is roughly equal to the load a 40-ft. boat exerts on its working anchor underneath regular situations. The cleat assemblies failed in one of four ways: fasteners, ft, legs, or the body of the cleat. The overwhelming majority of failures, (57%) were fastener failures. Feet failure, unique to four-gap cleats, and to zinc and aluminum cleats in particular, was second at 23%. Bodies failed 14% of the time, and legs failed solely 9%.

Fastener failures occurred with equal frequency in any respect three angles of pull parallel to the bottom (0°, 45° and 90°). By contrast, at the 45°/45° vertical angle pull, fastener failures accounted for less than half; the body of the cleat or its ft have been more more likely to fail first when pulled ahead and up. However, basically the cleats withstood better loads at this 45° upward pull than under straight pulls (the only two exceptions have been the stainless steel cleat and the marinium cleat). Because fastener failure predominated, it may be inaccurate to assess cleat power primarily based solely on the masses utilized. When the four loads every assembly withstood before failure are averaged, the stainless steel cleat meeting withstood the greatest masses, followed by the four-gap hollow marinium cleat. Not surprisingly, the nylon cleat ranked last, but it was stronger than we anticipated – it took a respectable 2,380 lbs. at 45° to cause the physique to fail.

Two Holes or Four?

The test revealed that cleat design is not less than as vital as cleat material in affecting what breaks, and at what loads. In case you adored this short article along with you would want to be given details about boat Fitting Sell generously visit the page. Four-hole cleats have been more more likely to undergo failure of the toes, legs or physique, whereas two-hole cleats suffered fastener failures 19 out of 20 times. We consider it is because the bolts in two-gap cleats are fastened instantly by means of the middle of the cleat, including energy to the entire meeting. It appears the load applied perpendicular to the axis of the bolts in two-hole cleats causes the fasteners to shear off at the bottom.

With four-gap cleats, feet failed 10 occasions in 24 pulls (42%). The toes failed consistently on half the 4 gap cleats, they usually failed beneath smaller hundreds than each different cleat besides the nylon. Of those three four gap cleats with constant foot failures, one was aluminum, one zinc and one Zamac. Since these three metals have equivalent tensile strengths and held their very own in the 2-gap category, there needed to be another explanation. We discovered the reply in foot floor space: the three cleats with constantly failing feet had the three smallest foot surface areas of the six 4-hole cleats we examined. We took a more in-depth look on the effect of foot floor space by comparing the very related aluminum. Marini urn 4 gap cleats (see · cleats F and G at proper). The ft on the aluminum-an enormous, beefy cleat failed on all four pulls. The marinium cleat had no feet failures. It had twice the foot surface space of the aluminum cleat (0.Thirteen inches2 vs. 0.07 inches2), and withstood greater than twice the load of the aluminum cleat.So, we deduced, the design of the toes , notably their surface space, is essential. Ironically, the weak-footed aluminum cleat was essentially the most costly of the eleven cleats we examined.


Although stainless steel has the best tensile power of a ll the cleat supplies we examined (double the tensile strength of aluminum, zinc, Zamac and marinium), it is nowhere close to the most costly cleat materials, nor does it essentially produce the strongest cleat in a given utility. This is because, as talked about earlier, a cleat is only one a part of a system, and that system is barely as sturdy as its weakest link.

Line is another part of the system. Generally, manufacturers suggest simply barely underneath one inch of cleat for each 1/16-inch of line diameter , which suggests you want a six-inch cleat for 3/8-inch line, an eight-inch cleat for 1/2-inch line, and a 10-inch cleat for 5/8-inch line. Using bigger cleats for larger traces provides both weight and expense, however what could be the purpose of utilizing 3/8-inch nylon line, with a breaking power ocleat you attach it to cannot withstand the same or higher load?

Chafe plays a significant role in the safety of any cleat system. You may scale back chafe by utilizing larger cleats, or cleats with smooth, round legs and no sharp angles, because the power of a line is reduced by bending fatigue when it has to show sharp corners or make tight bends. Mount your chocks as close to the cleats as attainable, and keep away from changing the course of the rope alongside its path via the chock to the cleat.

As a rule, you need to purchase the most important measurement cleat your pocketbook and the deck space can handle. Choose one made of a high tensile power material, like stainless steel , bronze, aluminum or marinium. Examine the toes to make sure they are massive relative to the dimensions of the cleat, sturdy, and have an ample thickness of metallic across the fastener holes.

Marinium normally costs slightly more than aluminum. Both metals have the same tensile strength, however marinium has a higher power-to-weight ratio. The marinium cleat held up better in our assessments, performing almost as nicely because the stainless. Zinc and nylon have the least tensile strength, and are the least expensive. But with zinc, as with aluminum and marinium, bear in mind of the potential for galvanic corrosion if you utilize fasteners of dissimilar metals (like stainless) in a saltwater environment. Nylon or plastic cleats are effective for small boat cleat rigging, flags and different low-load functions, but for moorings, docking, and ot her uses that involve the security of your boat, keep on with the stronger metals. Best buys on our test checklist are the four-gap stainless, marinium and bronze six-inch cleats, and the two hole aluminum cleat (B) at $16.95.

To deck-mount a high-load fitting like a cleat so that it’s actually sound and water tight, first strengthen the system by reinforcing the base. Use an beneath-deck pad twice the size of the cleat. One half cleat length across. On deck, use a pad about 25% longer and wider than the cleat. Use only stainless steel or bronze bolts (not screws) as really helpful by the producer, and stainless washers under the nuts to unfold the load.

Avoid locating cleats on mushy-core surfaces like balsa-core. If it ‘s unavoidable, then the core materials have to be eliminated and reinforced before set up, a job that is usually greatest left to an expert.