Sorry for the confusion, this is the principle that i am running off - this is not my actual design.
The design, is inspired from nature - much research has gone into biomimetic devices, and there efficiencys. Many research reports suggest higher efficiency's can be achieved using "thunniform" motion. However, the purpose for my actual design - is for a surfboard. I want dual functionality. So my thought, use the fins already inherent in surfboard design - allow them to propel the surfboard. Once on the wave, the power is disengaged and a mechanism will lock the fins back into place.
Here is a video, of a sample mechanism that allows for "pitch" motion, aswell as "side to side" motion - similar to what you would see with a penguin.
If anyone could help me to where to find parts of this nature, that would be great