To install third party addon boat models into your Vsk5 program you must first create a folder named "Boats" in your Documents/Vsk5/ directory if there is not a Boats folder already.

Boat Model Installation

Then simply open the Boats folder and copy and paste a boat model .zip file into the Boats folder.
Then launch Vsk5 and navigate to "Settings" then to "Boats". Then scroll through the boats to check if the new model was installed properly. 
NOTE - If you are using the free demo version (Vsk5Online) simply follow the same directory path. Instead of seeing "Vsk5" you will see "Vsk5Online" in your directory.