Age old Prop Question-1900sr

[jaycozer]

2001 1900sr 5.0L 220HP 1.47 ratio: Have a SS High Five 21P running only 4100 rpm and 40 mph-gauge only. Threw an old Al 3 Blade 19P than came with boat to see if I could get rpm up. Quicker out of hole without a 225lb skiier(me). But, slower out of hole with me than the high five used the day before. The Al prop did get me to 4600 rpm but started cavitating on smooth water as I trimmed up for speed. Never cavitated full trim with H5. Also only 35-38 mph WOT with Al 3 blade? Engine sounds great and solid but props seem out of tune/mismatched to keep giving these rpm/mph #'s. With only me and 2 others I've had the high 5 closer to 48, but with regular crew and watersports low 40's norm like above.

I bought a 18P 4 blade Quicksilver that I thought ran pretty good but only had short time because it was backed into a rock pile on maiden afternoon voyage. I don't know if 3 Blade Al 19P was original or not(it could also be out of true just getting banged around in anchor locker). I cannot find WOT numbers anywhere and wasted too many hours searching forums. Mercruiser prop selector suggests High 5 17P, or Rev 4 17P but that seems like too much of a change. Trying to see if trade for 19P high five would be best but really don't know WOT numbers for proper fit size. Had a trade available for 19P Rev 4 but that blade just looked massive and prop guy I gave the 4 blade to true thought so also and even told me not to trade him for the Rev 4 because I should be looking at the 19P H5.

Any others with my 5.0L 1900 setup have input. Slalom and some wakeboarding priority over 50+ speed.

[dronthelake]

Props are like shoes, there's one for every situation. We also have a 1998 Regal 6.8 (22') with a 5.7 and Alpha 1 out-drive. I carry a 15", 17", 19" and 21" and will change them during the day to suit my needs. The 15" is for knee boarding, great bite and keeps the RPM's up at the slower speeds. 17" for tubing with 6 adults. 19" cruising or tubing with a couple kids. 21" just cruising with 2 on board. All are 3 bladed. The 15 & 19 are AL and the 17 & 21 are SS Over the years I have tried 4 and 5 blade props but never liked them. They have great bit but tend to reduce the top end speed. I even tried the compost replaceable blade4 prop and had no use for it (very poor performance)

[jaycozer]

Thanks. I think I might end up with a couple of different props as well in the end. I would really appreciate any more info on wide open throttle numbers as well to help me with getting the props dialed in. With this engine, ratio and prop trials forthcoming I think I am targeting around 4800 RPM. Is the range 4600-5200? I do not have the manual and the supplementary PDF downloaded does not have these numbers. Any more input greatly appreciated.