One lesson became increasingly clear as the voyage progressed: Modern tools and materials were seldom a match for medieval ones. Not only did our plastic containers crack and leak, but expensive metal implements simply rusted away or broke, despite heavy layers of protective oil. Whenever possible we fashioned replacements out of ancient materials such as wood, leather, or flax, with primitive but far more durable results.
The same applied to clothing. As we reached colder latitudes, we abandoned our garments of artificial fiber in favor of old-fashioned woolen clothes with their insulation of natural oils.
As for the Brendan's hull, it actually improved in cold water. Daily inspection revealed that although the leather had become saturated with seawater, weeping a continual fine 'dew' on its inner surface, the increasing cold made the oxhide stiffer and stronger....If they had sailed through tropical waters, the higher temperatures could have melted away the vital wool-grease dressing on the oxhide and speeded up the leather's decomposition.I've been cozy in my thrice-shrunk wool sweater this week.