I will try to get a screen shot of this tonight, but I have found a way to mount on the boat, then jump onto the dock mounted and ride off.
I took the boat from the wetlands to Menethil, and I took the stupid boat that’s west of Dire Maul.
Anyway…
Go up to the second floor, and walk out on the ropes towards the side you will have to get off the boat. Then walk forward, on the rope until you are on the 45 degree slanted part, that slants forward (you will now be standing at an angle down). Now click mount. Keep trying it and you will get it. In relation to the opening on the boat you walk back onto the dock, it is closer to the back of the boat (but not past the end of the opening) where you can mount. Once you are there, jump off the top, and you’re set (don’t just walk off).