sentences:  In 1766, because of the poor condition of the iron bolts, "Alarm"'s copper was removed.After this experiment, and deterred by the unanticipated and not understood electrolytic reaction between the copper and iron, lead sheathing was tried again, though it was found to be unsuitable to the task, as the plates tended to fall from the hull alarmingly quickly.By 1764, a second vessel, , had been sheathed in copper, specifically to prepare it for a voyage of discovery in tropical waters.