Tach Beam 3 is quite potent, especially when used on the Focus target just before or during an alpha strike (Covariants don't drain as much, but they don't come back quickly either and the opposite is true for Regens).
You just need to ensure that all of the Tach Beam dependent skills are maxed, you have the appropriate Science consoles, a deflector that supports it and a high AUX power level when you fire it off.
The common newb mistake is AUX power, while the more experienced people mess up with the supporting skills / equipment and the final hurdle is the timing+proper target it is used.
I have a SCI BoP as well, I just don't list him. I know the temptation to setup for damage and forsake the Science abilities somewhat can be very tempting sometimes =)