Prop selection

"Have a 1995 Crownline 20'

"Have a 1995 Crownline 20' open bow with a 5.0 mercruiser using a 19 pitch SS prop. Top speed is 44 MPH at about 4200 RPM. Is this a good prop for skiing or should I drop down to a 17 pitch? If I wanted more top end speed, should I go to a 21 pitch? Any info greatly appreciated."

What you have stated is all co

What you have stated is all correct. Caution to check your manual and find out the max RPM'S of the engine because the smaller pitch will generate higher RPM's (I would expect your max is 4800 but you need to check the manual or call a local Crownline dealership).
You need to ask your self what is most important hole shot for skiing or top end for cruising and then choose your pitch. You will lose top end with the lower pitch prop.

What trim level are you using?

What trim level are you using? Just changing the style of prop can change speed. Your boat sounds like it is propped correctly as far as pitch is cooncerned. You may want to try a cupped performance prop for top end speed. If you are using a dole fin or other type of extension on the drive it will aid in getting on plane faster but will scrub off top end speed. I carry 2 props with me. One for skiing and one for top end. It takes all of 2 min. to change and a floating wrench is all of 10 bucks. Prop shops around here will let you test drive props if you don't bang them up. Prop selection I have found is an owner prefferance thing. Max rpm on merc alfa one drives is 4600-4800 rpm. This normally where stock marine engines make the most propshaft hp. Even though a small block chevy can runn 5500+ all day long.