Top speed only 28mph...Is this right?

[imported_Captain Morgan]

I just bought my first boat. It's an 88 Wellcraft Classic 17' open bow ski boat with the 3.0L Mercruiser engine. It only registers 28 mph on the speedometer with 3 people on board (weighing an average of 200lbs each). This seems low to me. Is this right for this boat with this engine? If so, I'm going to be a little disappointed. I bought a new speedometer pitot tube but have not had a chance to try it out yet.