sometimes when placing down a boat on the ground it just disappears and is no longer in the inventory. included here is a video of it happening it to a streamer on twitch. I have also had this issue firsthand.

video: https://clips.twitch.tv/DullSoftWrenchTBCheesePull-Qtu9NGc7sZAFnrTQ

1.) place boat

2.) see boat item leave hotbar

3.) see boat not placed

expect the boat to be placed down consistently without disappearing.