The boats that are not a problem are:
- the large boats that go between MK and the Ticket and Transportation Center
- the Friendship boats that go between one side of World Showcase at Epcot and the other side
- the Friendship boats that go between Epcot's International Gateway and the Epcot area resorts (BC, YC, Swan, Dolphin) and the MGM Studio
Those boats use floating docks and have ramps. The docks are close enough to the boat level that we don't usually use a ramp for our DD's manual wheelchair.
The boats that are not accessible unless you can get out of the wheelchair, lift the wheelchair down several steps and step down onto the boat are the small boats that go between the MK resorts (GF, Polynesian, Contemporary) and MK.
The larger boats that go between MK and WL may or may not be accessible. Sometimes the water level is too high or too low, which makes the boat float too high or too low compared to the dock. The CMs have some ways to deal with it - ramps work if the difference is not too large. The CMs have other ways that may work - like loading the wheelchair first if they need the boat to be light to float high in the water or loading all the other guests first if they need the boat to be low in the water. Someone reported once that the CM had everyone on the boat move to one side so that side of the boat went lower in the water and the other side went higher, closer to the dock level.
Even when the water level is sort of 'iffy', someone with a manual wheelchair might still be able to ride the boats - especially if they are small enough to pick up and lift onto the boat (which we have done more than once with DD in her wheelchair). In that same situation, someone using an
ECV or power wheelchair would not be able to ride.
From GF, I would agree with the suggestion to take the monorail. A wheelchair can be wheeled right onto the monorail. The monorail stations are at 2nd floor level - not a problem at the resorts, where the station is level with the hotel floor. At MK and the TTC, there is a long, steep ramp to get from the station to the ground; there are no elevators. The station at Epcot has a long ramp, but there is also an elevator (ask the CMs if you don't see if).