EMB ERJ 145 ER/LR
Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Flight Crew Last 90 Days 200; Flight Crew Total 3700; Flight Crew Type 2940
Situational Awareness
Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Weight And Balance
General None Reported / Taken
Human Factors
All seats on board were occupied; plus a jumpseater. After sending the weight and balance via ACARS; the numbers returned stating a need for 250 LBS of ballast due to being 2.1% out of forward CG limit. I pointed this out to the captain who said 'nah; we don't need ballast. Put the number in there and resend it'. I stated my concern for that practice then reiterated with 'are you sure you don't want ballast?' to which the captain responded 'I'm sure'. I pressed him again and he says 'I'm positive'. He entered the 250 into the ballast field and resent the Weight and Balance computation. The jumpseater; a captain for another airline on a different aircraft; did not voice any concern at all.  I regretfully went along with the captain's decision; despite my protest; and we continued to [destination] without incident. Had an incident or accident happened along the way; any investigation would have discovered no extra ballast on board the aircraft and while just about every captain at my airline would say 'it's not your certificate on the line; it's mine'; I know the next question an inspector would ask is 'where was the First Officer?' I should have spoken again with this concern and been more assertive about a bad practice. My reluctance to force the action by simply telling the ramp crew we needed it was likely amplified by the fact another captain was on board; my mental submission to an idea of 250 LBS in a 46;000 LB aircraft being a potential 'rounding error'; as well as the fear many FOs have in not wanting to upset the CA and being labeled as 'difficult' or 'that guy'. I had briefed 2 legs previous that I was there to help and 'keep us out of trouble'; but with my shortness of action; I could have done almost the opposite and contributed to said trouble.
EMB-145 First Officer reported departing; at the direction of the Captain; without required ballast to correct a CG problem.