Like Steve's underwear... it "depends". 
(Good to see you around, mate!)
The mass and inertia Steve refers to goes both ways. Once you overcome the inertia to get your tanks moving it wants to keep moving until drag slows it down. It's why we coast. Your trim in the water will affect your drag far more than any variation in tank. Sure, there's some loss with the inertia. In addition to being horizontal, your trim should be effortless. If you're constantly fighting to stay in trim, you're consuming a lot of gas doing so. If it's not effortless, then you need to adjust weights forwards or backwards until it is.
Most people with high SACS tend to have other energy drains like hand sculling or nervous tics. The less you move, the less CO2 you create and the less you need to breathe. You should be able to simply stop mid water and relax with no extraneous movement.
(Good to see you around, mate!)The mass and inertia Steve refers to goes both ways. Once you overcome the inertia to get your tanks moving it wants to keep moving until drag slows it down. It's why we coast. Your trim in the water will affect your drag far more than any variation in tank. Sure, there's some loss with the inertia. In addition to being horizontal, your trim should be effortless. If you're constantly fighting to stay in trim, you're consuming a lot of gas doing so. If it's not effortless, then you need to adjust weights forwards or backwards until it is.
Most people with high SACS tend to have other energy drains like hand sculling or nervous tics. The less you move, the less CO2 you create and the less you need to breathe. You should be able to simply stop mid water and relax with no extraneous movement.
