This course I mapped out was 3.8km, x 2 laps.... So, pretty much 8 km. The inshore course is accurate, the outer portion of the course is a guestimate. But the even when you trace the outer points quite wide, you only get 4.0km.....
This second course is 4.0km, but the above course is a better reflection. But yes, the below course does look like more than 200m extra, but trust me, it's not. And actually, the above course is a shade under 3.8km.
So, by hook or by crook, we seemed to have had an 8km course.