Last November at WDW, I was surprised when they placed my manual wheelchair in the back of the boat on Pirates of the Carribean. What do they do for ECVs? (Say a typical park rental size?)
They have wheelchairs there at the entrance that you can switch to.
Someone with a power wheelchair or non-folding wheelchair has to do the same thing. Keep in mind when leaving your ecv or wheelchair that the entrance is quite a ways from the where you will get off.