As an alternate, you COULD walk the very short distance from the boat dock to the DTD bus stop and take nearly any bus to the West Side (where DQ is located).
Most all of the resort buses go from DTD to the West End before they return to the resort (just ask the driver before you board).
The POR boats USED to ALSO go to the West Side in the afternoons... don't know about that any more.
I can easily walk from Rainforest to Disney Quest in ten minutes and I'm 54 years old. Don't cut through PI. Go along the sidewalk nearest the parking lots and cut back in between Planet Hollywood and AMC. It's faster.