Captain Smith had ordered more boilers to be lit so they could continue traveling at full speed which was about 22 knots. Smith thought they would be able to see any icebergs and would be able to change course to avoid them. It was also unusual for icebergs to be that far south. There was no moon that night so they could only rely on visual sightings plus they ignored warnings of heavy ice patches.
on this show about titanic said that the titanic was going fast when the spotted the ice burg this is were the mistake happen Smith ordered the engines to go in reverse the he turned the ship which was the mistake he made if he would've rammed it head on the would crush and titanic would have survived but since he turned titanic couldnt slow down fast enough and scraped it tore a hole through 5 boiler rooms