"Heres a good article describing why ships float
Archimedes' Principle of Buoyancy
http://www.bible-history.com/resource/ff_float.htm

And another why a fat person floats better than a heavily muscled person.
Body Buoyancy
http://www.newton.dep.anl.gov/askasci/gen06/gen06428.htm
They both in a way apply to a terminator, who is shaped like a human, but far more dense, and does not displace any more water in trying to float."

"Mmm, I think you don't get it.

A body floats if its average density is below 1 kg/dm3. That's all, folks.

Now, the density of flessh is much lower than 1 kg/dm3, I should ask Mhall that the last time gave me the precise number, but let's say that it's 0.7 kg/dm3, -30% than water. This means that a body just made of water would have 30% of mass more, and we already are over the values that the writers indicate as "realistic" for them.

But here we aren't talking about water, we are talking about a ti-based alloy. Do you want to know the density of Titanium?

4.506 g·cm−3 while for water is 0.998 g/cm³ (liquid at 20 °C, 1 atm)

http://en.wikipedia.org/wiki/Titanium

And with this, the game is over,even considering that half of the terminator is metal and half flesh we would have an average density "floating" around 3 gr/cm3, this would mean that a terminator is effectively of a weight of 600 lb...even this extimation is pretty...optimistic.

And that's all, good night and good luck! "

"<snip>
Ivy, concede the point, you're like me. We're both wrong because we can't fight the rules of the universe, and a hyperalloy can't have a density less than the materials it's made out of. I think."

"For all intensive purposes, since we've hit the border between what's factual now, and "realistic fiction" (yes an oxymoron), the Turk, as mentioned by Ivy, said "hyperalloy." Now, in the fictional world, this could mean many different things, including discrepancies in density. Although, I'm not well versed enough to know if an alloy's density is equal to the sum of the proportionate elemental densities. It could be a hyperalloy, which is formed into a matrix (similar to that of a crystal). This would increase rigidity of metals (all metals are pliable to a degree), and decrease density, by causing a porous matrix inbetween, which could house who knows what kind of essentials (similar to the spongy portions of our bone). So, I'd say the design may matter.

I want you to understand I was never a "big fan" for the "termi's are heavy!" notion. It just made sense, as an educated assumption, and my defense of it was exacerbated by people's hasty willingness to jump the "light" train. In today's world, such a design is impractical. However, Turk says "hyperalloy", and this is fiction; that's something we, as sci-fi fans, have to accept. I know, I played some devil's advocate here, but I think we're all on the same page. Regardless, whether Cammie weighs 140 or 250, she's badass either way (and this is a good example why this show rocks, because we're here brainstorming over stuff like this."

"Alright, so I was wrong about the density thingy, but still, it makes sense that the Terms are made out of a metal alloy which is still very denser that water. :)
Also, that Aerogel isn't a metal at all. I stand by what I said about metal. Also, can something be a hyper-alloy and not be made out of metal? The heck? Ivy, you're killing me here. Changing everything that I know..."

"If we're both quick you can edit your post and I can delete mine and we can all pretend it was like that all along ;-)"

"It may also be that the endo material can heal itself in a manner similar to the artificial skin... we've never seen Cam repair herself other than to pull out slugs from her skin. Perhaps she kept the bar of coltan to chew on after a particularly gruelling encounter..."

"All I was trying to say was that the endoskeleton need not be solid metal.

The wiki entry mentions aerogels made of alumina, chromia and tin oxide. "