You can swim twice as quick as this (ignore this if you already do). It's an easy fix. You are bending your knees almost like you were trying to walk. Because of this, your legs sink down together with your hips so the water slows you down. Not to mention you are kicking the water down - that can't drive you forward. Your spine and legs should be parallel with the surface, the knees almost straight (but not stiff): the movement comes from the hips, the knees only follow. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-d-6nhtCfzXY.html