airboat

noun, a flat-bottomed boat with a large propeller mounted above the rear transom generating a rearward thrust of air, capable of travelling very fast and used esp. in shallow and marshy or weedy water but also over ice (COD)

“Airboats, when the ice was iffy you could pull yourself across. It had big propellers on behind it that turned and pushed you. It would go on the ice and water.”
“Yeah, if the ice was thin then it’d go through water and then bring itself back up on the ice on the other side wherever they were going.”

“Yeah, Len built his airboat. Well, it wasn’t the first airboat on the Island. They had bought this big airplane engine they had in it, and then he decided to build his own, little smaller. They used it quite a bit, ’cause he used to carry the mail.”

“It was an airboat like the type they run in the Everglades, you know? So they can run on water or run on ice.”

“That’s how we used to travel across the channel if there was no ferry. And then everybody started getting airboats.”

“Who was the first one to have an airboat on Simcoe?”
“On Simcoe? That might’ve been Tom or Len. They had one that had the airplane motor on, eh. It had lots of whump.”

“Yup, so you rode in the airboat.”
“It had a great big fan at the back.”