Hi, MR.Morris
I am The Grey Wolf, I am also very new to RC Submarines.
All I know about RCSubmarines is that you get two types of RCSubmarines: Dynamic Submarines and Static Submarines.
Dynamic Submarines use their hydroplanes,rudders and speed to keep them submerge underwater, if the Submarine loses it speed, it will ascend because it does not have a Static (OrBallast tank) dive system in it to keep it underwater.

Static Submarines use the static dive systems to keep them underwater, which is like the real thing because it has a Ballast tank in the RC Submarine. The Static dive system is another name for a Ballast tank, whichoperates like a real Submarine.

Hope this helps.
Keep well,
The Grey Wolf