Volvo 572 SP Prop Confusion

"I recently purchased a 1993 W

"I recently purchased a 1993 Wellcraft Excel 23 cuddy. It is equiped with a Volvo Penta 572 SP. I however do not know what model outdrive I have. I have taken the prop off and have a part number of C. 851138 (14x21 L) I tried to cross refernece it and came up with another part number 854479 which I assume it has changed to. My problem is the numbers show up as long hub style and the measurements I have taken show it to be a short hub style. I really dont know what style prop I should buy, I might also add that the prop is mounted with the same hardware as the long style hub and not with all the other parts that are shown on the short hub style."

"With a 572, you should be run

"With a 572, you should be running a long hub prop. Also, a 23 ft boat should probably use a 15" diamater prop, not 14". Check page 36 (54) on the link below.

http://www.miwheel.com/MIWheel/pdf/99021208.pdf"

"Well that is what I thought b

"Well that is what I thought but I am confused by the actual shaft on the outdrive and the measurements I was using from that page. I have attached a picture of the shaft. Would the larger diameter prop improve holeshot? I am looking to decrease time to plane and not compromise too mush top end performance.
<img src="http://img370.imageshack.us/my.php?image=dsc004362hn3.jpg"">"

"Is the propeller shaft origin

"Is the propeller shaft original in our outdrive, or have you replaced it? Also, what is the measurement from the end of the spline to the shaft recess (where it changes diameter) if you remove the thrust piece or spacer that is still installed? My spare outdrive shaft measures 3-1/4" like yours, but from the end of the line cutter spacer (which you don't seem to have installed). Mine can handle either long or short hub props, but I have two different sets of propeller nuts.

Also, is the threaded tip of the shaft also have an internal thread? If so, it should handle long hub props.

A larger diameter propeller will give more thrust and theoretically a better hole shot, but there is a chance that the top end speed may decrease slightly. You also would likely have to go down in pitch about 1-2". That is, if you now have a 14 x 21, you probably would have to install about a 15 x 19."