For centuries, oak was the wood of choice for European shipbuilders. However, toward the end of the eighteenth century, as British oak supplies grew scarce, shipbuilders there turned to teak and found in it an ideal substitute. Other woods expand and contract at different rates than oak, so repairs to oak ships done with those woods split or leak. Only teak matches oak's expansion coefficient and stays watertight. It is unmatched in its resistance to rot and pests, and its oils even protect nails against corrosion. Moreover, it was one of two important tropical hardwoods (with Central American mahogany) that dried light enough to float downriver – the only way to transport timber in quantity from the inland jungles where it grew.