Wear Mechanisms applied to Lifeboat Slipway Launches

It is necessary to use an inclined slipway to launch a large lifeboat in locations where there is no natural harbour or where there is a large tidal range. Slipway stations consist of an initial section where the boat is held on rollers followed by an inclined keelway of nickel/chromium coated steel, the lifeboat is released from the top and proceeds under its own weight into the water. The lifeboat is subsequently recovered to the top of the slipway using a winch line. With the new, larger Tamar class lifeboat, existing boathouses are being upgraded, and existing low-friction coated steel slipway lining materials replaced with a low-friction jute fibre/phenolic resin composite, which is designed to operate with unlubricated conditions, leading to problems of high wear on slipway panels. A method for assessing slipway lining materials and lubricants, including factors such as seawater and wind-blown sand contamination, the selection of an appropriate test machine, the TE92 rotary tribometer, and the design of a modified ring-on-disc arrangement are described.