No, not the big ferry that goes to the TTC. Or the monorail, because getting all the way around the loop with stops at the CR, TTC and Poly can take a good 40-45 minutes.
Save the monorail for a "souvie haul crawl"

, because there are great shops in the monorail resorts.
You'll want to take the smaller boat at the dock near the ramp up to the monorail station. That's the one that goes MK-GF-Poly. It's a pretty short ride, maybe 15 minutes, fun and relaxing with a cool breeze the whole way. You'd think I'd remember as often as I've done that how long it takes, but I don't.
That boat is a great way to get to the GF, because it's not very far from the GF dock to the outside QS entrance to Gasparilla's. Do look over the Gaspy's menu before doing this. It might be too exotic for your tastes.
Though since you mention 11:30, if you're getting an ADR for GF Cafe, go up onto the veranda at Gaspy's entrance and turn left along the veranda around the side of the main building. You'll come to the veranda entrance that's near GF Cafe--which is YUMlicious, by the way.