The shared boat

The shared boat

Three rowing friends have a boat in common and want to manage so that each of them can use it at any time without any stranger can take it. Each of them has a lock with its corresponding key and they want to tie the boat with a chain locked by the three locks, each of which is opened with a different key.

Each friend has only one key, which corresponds to their own padlock, however with it you can take the boat without waiting for the others to arrive with their keys.

What did they do to get it?