After all this time there is one feature of the game that has just recently dawned on me,I can't believe I have'nt mentioned it before,but when you cycle between tubes either by pressing 'Y' or manually clicking the corresponding number,why does it sometimes keep opening and shutting the doors?.This is both detrimental to losing vital seconds AND annoying

I only just noticed it moments ago,after messing around in the academy trying new ways and tactics on the small convoy.I fired first at the s.tanker,then at the c2,and then a s.merch,but when it came round to nailing the c2 the bloody doors shut on me.I quickly set the torps up again,and again it did it.
Not what you might call 'handy' when you quickly want to fire multiple torps at different targets