Strength testing of boat cleats

The strength capabilities of eleven types of cleats were investigated for the Boat U.S. Foundation. Each cleat was tested in four loading orientati6ns which simulated real-world applications of the cleats. This was accomplished using a hydraulic press which applied force on each cleat with a 1/4" steel cable until the cleat broke. Two mounts were designed and created to hold the cleats at the bottom of the press in the proper position for testing. The data for each test included breaking force, loading orientation and failure mode. The results of the tests varied significantly. Although mounting screw breakage was the most common mode of failure for the cleats, several of the cleats suffered from mounting hole and main body failure. Two stress analyses were performed following the testing in an attempt to provide a simple method of predicting cleat strength and performance capabilities. A simple analysis provided vague and inaccurate results. The second, more complex analysis, produced a better understanding of the stresses experienced in the loaded cleat system, but many uncertainties were still prevalent. Predicting the exact failure force and mode from a stringent analysis would be a monumental task. Complexities such as stress concentrations, manufacturing inconsistencies, and loading irregularities make such an analysis useless for the typical boat owner. Therefore, the analysis"was only capable of providing broad statements about poor and efficient cleat designs. One cleat type was broken in the same method four times with a breaking force spread of about 1000 pounds. This revealed the inaccuracies involved in testing and analyzing the cleats.

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