Companionway slide failure; a solution.
Sunday - October 25, 2015•Views: 861••
Amateur assessment of companionway slide failure:
The failure of the slides is apparently due to the expansion and contraction of the slide material, and its inability to tolerate the movement at the fasteners. All of the fractures are at the fasteners. My goal is to replace them once, and provide for the movement to avoid future failure. My choice of material for the replacements is Starboard, which I am told is now used by the factory. Starboard expands 1/32” per foot of material per 40 degree change. In New England, that’s a sixteenth of an inch (or more) of back and forth movement between the fasteners. The material fatigues, and eventually breaks at the attachment points. King Plastics, the maker of Starboard, recommends oversized fastener holes to accommodate the movement, but that’s only half the story. The factory used countersunk wood screws. Even with an oversized hole for the shank, the tight fit of the beveled head restricts movement of the material. My solution is to counterbore, rather than countersink the hardware and use pan head screws rather than wood screws so that the material can move under the head. The first photo shows the two sets of slides; the second shows the two approaches to accommodating the hardware. My expectation is that with this simple change I will never have to replace the slides again.
The failure of the slides is apparently due to the expansion and contraction of the slide material, and its inability to tolerate the movement at the fasteners. All of the fractures are at the fasteners. My goal is to replace them once, and provide for the movement to avoid future failure. My choice of material for the replacements is Starboard, which I am told is now used by the factory. Starboard expands 1/32” per foot of material per 40 degree change. In New England, that’s a sixteenth of an inch (or more) of back and forth movement between the fasteners. The material fatigues, and eventually breaks at the attachment points. King Plastics, the maker of Starboard, recommends oversized fastener holes to accommodate the movement, but that’s only half the story. The factory used countersunk wood screws. Even with an oversized hole for the shank, the tight fit of the beveled head restricts movement of the material. My solution is to counterbore, rather than countersink the hardware and use pan head screws rather than wood screws so that the material can move under the head. The first photo shows the two sets of slides; the second shows the two approaches to accommodating the hardware. My expectation is that with this simple change I will never have to replace the slides again.
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