Serpentine belt/Power steering pump promblem

[Catahoula]

We picked up our Chaparral 2003 230 SSi with Volvo 5.7 GXi in April. The boat has less than 100 hours on it. After the second outing, there was a lot of belt shavings in the bilge and about 3/16" shaved off of the front of the belt. I got a new belt, checked everything out and put the new belt on. I didn't see any shiny spots on pulleys, didn't note any wobbles or stiff bearings or see any significant alignment issues. Took the boat out today, and after about 4 hours on the water the belt had a fairly clean cut through, cutting about 3/16" off of the front edge of the belt again. Both pieces were intact, basically leaving a wide belt and a 3/16" belt on the pulleys, if that makes sense. I took the belt off after noticing it riding over the edge of the main drive pulley. Everything checked out ok except the power steering pulley. It has no side to side play or wobble, but I can move it front to back about 1/4". The pulley is tight on the shaft, it is the shaft moving back and forth in the pump. I'm assuming this is not normal and could be causing my problem?