Prop help needed

"First off, I'm new to thi

"First off, I'm new to this site,and so far i'm amazed at all I've learned so far....Thanks.

I just bought a 1980 Bayliner with twin 470's. The previous owner put two brand new props. 16" x16p. The problem is that when the engines hit 3000rpm, the starboard sounds like it's cavitating. The prop is fine, but replaced the hub just in case, same problem. I found one of the old props on the boat its 14.5" x 19p. Is the boat over propped with the 16's. Any help would be greatly appreciated."

"It sounds like it is overprop

"It sounds like it is overpropped. Use the propfinder to determine what prop you need.

Select boat type #2, input total loaded weight, input max. RPMs, input horsepower, input altitude from sea level--don't know? use 500' unless you live in the mountains and "0'" if you live along or near the coast.

<center><table border=1><tr><td>http://www.marineengine.com/discus/icons/mime_msexcel.gif""" align=left alt=""application/vnd.ms-excel"">prop finder
[url=""][b]Boat_Speed_Finder-79780.xls[/b][/url] (22.5 k)</td></tr></table></center>"

"Guy\Rod - I would think prop

"Guy\Rod - I would think prop diameter would enter into the equation, but I do not see it referenced on the spreadsheet. Is it a factor?

thanks
bill"

"Diameter is not such a big fa

"Diameter is not such a big factor in WOT top speed, since the prop is at minimal slip at that point. The spreadsheet assumes that the prop diameter is average for the boat and engine combo.
From my experience, too big a prop may have too much blade area for the engine to turn from a dead stop, and the engine will not be able to get up to good torque RPM range easily enough. So hole shot suffers.
Rod"

"thanks for all the help. I&#

"thanks for all the help. I'll probably change the props, but first i'll get rid of the seafood buffet attached to the bottom of the boat."