Design 

VEHICLE SIMULATOR (or VSF = Vehicle Simulator Frame) and VIRTUAL SAILOR NG (or VS NG) are excellent vehicle simulators developped by ILAN PAPINI. Beyond their main quality of having very good nautical dynamics, they are open world simulators allowing you to create sceneries, vehicles of all types and test them.

To know more and eventually purchase one of these go to http://www.hangsim.com
 

On this site you will find some of my models (boats or other floating objects) to use for free in VSF and VS NG.