This is one of the many bookmarked links that we use & share (schedules subject to change, of course - please confirm) -
http://www.cantontradefair.com/trans...hou-Ferry.aspx
Just FYI, travel to GZ & Macau is typically by Turbojet and/or Fast Ferry, those prone to motion sickness are cautioned to take measures as the waters & going up river can be choppy. Direct routing over water is roughly about 2 hours - years ago & I mean a long, long time ago, there was slower - overnight "slower" boat to/from mainland - nowadays, preference and demand is for fast & direct options like a 35 minute flight or HSI train.
Depending on your travel dates next month, beware of the annual mass migration in travel due to upcoming national holiday period and billions on the move, don't want to be "caught" in the tidal wave of mainlanders heading "home" everywhere. Book ahead & confirm your ticketing and enjoy the trip ... hopefully.