Run a
sed[/m] recipe or [m]awk script over all the relevant pages. Something like (and this is
untested):
$ find pages -name \*.txt | while read fname
do
mv $fname ${fname.old}
awk '{ gsub(/ship/, "Boat"); print }' < ${fname.old} > $fname
done
You'll need to remove the
.old files later once you are happy with the changes.