This is an act of piracy and should be treated as such. If you fly the colors and board other people’s property I call that an act of piracy.
I live aboard a small cruising sailboat and having known hundreds of my ilk, can state the the response of a boat owner seeing a stranger set foot aboard uninvited, as similar to the homeowner who sees a bedroom window open and a stranger enter. Even
friends ask for permission aboard out of þoliteness; strangers ignore this courtesy at their peril.