From the Vancouver Port Authority's Harbour Operations Manual:

Reposted from Rampage_Rick:

On page 21, under section 3.1.5 is the following:

"Sailing or proceeding without mechanical power (rowing and paddling) is prohibited in First Narrows. One sail sheeted home is allowed for stability purposes when under power in the Narrows otherwise sails are to be lowered.
The use of personal watercraft in First Narrows is prohibited."

Section 3.1.1 says this:

"First Narrows is defined as those waters in Vancouver harbour bounded to the east by a line drawn from Brockton Point to Burnaby Shoal, then 000 degrees True north; bounded to the west by a line drawn from Navy Jack Point to Ferguson Point."

*edit to add*

Turns out the actual name is Navvy Jack Point, and the BC Geographical Names Information System lists the exact same coordinates for Brockton Point and Burnaby Shoal, so one might argue the rule ambiguous. (Like the guy who successfully fought a ticket issued for "no stoping")

If one interprets the spirit of the rule, it should look something like this: