Underwater physics

I'm trying to develop an underwater simulation, and one of the things I'm starting to see a problem with is the mass of an object and how that works with water. For instance, I'm going to have a ring be underwater, and as you've probably seen, a ring acts a little funny underwater. I guess it's due to the friction of the water and such, but it starts going straight down, then it will turn over and do some swooping motions.

Does anyone have any ideas of how to mock the physics for such a thing? I was thinking that if the mesh actually had weight, maybe that could determine how the object moves. But, I'm a little stumped at this point. I did find a ring mesh online for free, but I'm not sure how to configure it to 'drop' properly.

Thanks for any help!

 

Im not sure, could this script help?
http://www.unifycommunity.com/wiki/index.php?title=Gravity

If that doesn't work, you could try something with addforce but I'm not sure.

Hope some of that jibber jabber helped ^_^

 

Thanks! I'll definitely check that out.