Pirate School Series by Brian James, Jennifer Zivoin

The pirate ship's first mate, Rotten Tooth, sees Pete and his friends more as an annoyance than pirates in training. As the ship heads toward Snake Island, Pete has an idea to earn some respect--if the kids can find the hidden treasure before the grown-ups, then they'll have to be taken seriously! Only one problem: The treasure is guarded by a giant snake that curses anyone who looks in its eyes. Can the pirate kids find the treasure, earn the pirates' respect, and escape certain death?

Rotten Tooth has finally decided it’s time to teach the pirate kids some real pirating skills! They are overjoyed—until he begins by showing them how to tie and untie different knots. BOR-ING! But one night while the kids are below deck practicing their knots, the Sea Rat comes under attack by the Filthy Sails, a rival pirate ship! When the intruders overtake the ship, it’s up to the kids to sneak around and figure out how to save their crew. Can they save the Sea Rat and its crew?