IIRC all the wood was vulnerable to either ship worms or rot eventually, they had to replace masts and rudders and scavenge from the least seaworthy ships (and

IIRC all the wood was vulnerable to either ship worms or rot eventually, they had to replace masts and rudders and scavenge from the least seaworthy ships (and scuttle if necessary) and opportunistically get wood from any island they could make landfall on to make the journey described in the book.