I have used a similar aproach, but I don't hash them. Here's a example:
Supose I have the master password "t3st1ng" and "!@#" as separator. When I want to register on site www.reddit.com, I just use the password "reddit.com!@#t3st1ng".
This way I always have a strong password and I can use different passwords in every site, and I just have to remember the master password.