Everyone dreads getting caught inside.
"Open your fingers!"
" I can't make it!"
This subject was covered in an earlier post.
Olympic swimmers spread their fingers for more power.
Water is cohesive, it sticks to itself. Water molecules bond together when a speeding object moves through it. Inter molecular hydrogen bonding, creates hydrodynamic resistance. When a hand moves rapidly through water, it generates wave making resistance. A tiny wave is created, which gives power to a stroke. When the paddler opens his fingers, he creates more resistance similar to a larger paddle. The stroke with fingers open, will pull more water in the form a larger hand made wave. The surfer will experience more thrust and acceleration. He must adjust his stroke timing and condition his muscles, as more strength is required.
Move your open fingers slowly through water, it drains between your fingers. Add speed by flicking your open fingers upward to the surface, through a body of water. Water will not drain between your fingers, instead; water will fly through the air. Speed generates hydrodynamic resistance in the form of a wave. Water sticks together in a wave with open fingers. The same experiment can be done with a fork. Flick a fork through soup. You will be able to consume a fork full, if your aim is good. A similar experiment can be done under a faucet, if the stream is not aerated or past through a shower head.
Videos and pic from youtube.
Merry Christmas and may your New Year be filled with perfect waves.