Mechanical design of Swimming Platform

Hello! I'm new in this forum. I'm from Argentina and i am currently working on a project of a Swimming Platform.

The general idea is to design something like this:


The problem is that i don't have enough knowledge about mechanics so i want to know if you could help me to understand the mechanism of this platform.

I understand that it is a system of gears and chain where each step has a pinion of the same diameter and at the end has an inverter that rotates in the opposite direction.
The problem is that I do not understand how the elements are linked and how to make the arm rotate on its axis.

 

Can you start by posting photos of the boat the platform will be mounted to, and a sketch of what you want it to look like Sprockets and drive-chains under water are going to require constant maintenance and repair. The video shows a mechanical not a hydraulic system.

 

Gonzo, thank you for your answer.
Indeed, the platform will be mechanical and not hydraulic because it will be used in fresh water, so although there will be wear on the parts, corrosion is less.
I don't have a photo of the boat at the moment but the system it's like the Opacmare Transformer:



The main difference is that I want it to be 100% mechanical (the Opacmare has a hydraulic system)

 

I would opt for hydraulics, all those gears and chains and pivots and bearings are sure to suffer from exposure to the elements.
Hire an engineer to work it out, his stamp will be required.