One thing to keep in mind, is that the slow speed of the vickers (18-20 kts on the surface, roughly 17 submerged) make its 120 seconds of air seem to never last long enough. I remember, before my acct was archived, that when I first played the vickers, I spent most of my time just trying to survive long enough to submerge and reach the enemy. The next class up, I had enough speed to submerge almost within my own start area and still reach the enemy.