Stanley park is really big, but if you get an early start, you could probably do it in a morning, though it would be tight depending on what you actually want to see. The hop on hop off trolly took an hour to make a full loop of the park and while it's stopping for a few minutes at each stop, it's moving around 30 mph or so while it's driving. You'll be biking much more slowly. Looking at the Navigator from our sailing a couple weeks ago, the lunch buffet closed at 2:30. It took us around 45 minutes to get through check in, customs and passport control so factor that in, plus returning the bikes and making your way over to Canada Place (plus, I assume retrieving your luggage from your hotel unless you're staying at the Pan).