Getting into a boat from the water is HARD. The drag of the water makes it difficult to jump, and there's often no bottom to stand on. Even if you're in good physical condition, it's quite difficult to heave yourself more than about 15 to 30 cm (6" to 12") vertically out of the water. Take a look at a swimming pool: the copings are rarely more than 15 cm above the surface; in the best modern pools, they're level with it. Most people just can't jump any higher out of the water.
Let's look at Sunset Chaser for a moment: