Still trying

Mr.Kitch'nPass · 05-20-2003, 07:25 AM

Im still trying to prop my boat.Someone had said do not change the diameter only the pitch is there a reason for that? :whazzup: The guy at Ampro says to try it.I think they may just want me to try what they have in stock

Any Thoughts?
Thanks Dave

Sensei-san · 05-20-2003, 07:56 AM

The diameter of the wheel is constrained by a number of factors; on an I/O or outboard, by the cavitation plate above the wheel. You can't fit a 24" diameter wheel on a shaft where the cavitation plate is 11" from center line. On a direct drive boat you have the same problem plus the surface tension effect. The closer the wheel is to the hull, the less thrust you can develop as water friction will increase across the hull.

If you are fine tuning to get more revs or more speed, repitching is the easiest and most economical way to go. Often adding a small amount of cup to the wheel will make the difference.

Most professional propellor shops have tables to figure out the correct pitch and diameter for the boat and the powerplant you have. Look for a shop that is a PropScan member.

[ 05-20-2003, 09:37 AM: Message edited by: Sensei-san ]

Myles · 05-20-2003, 12:35 PM

Dave how much under specified WOT is your motor running? Mine was revving up to max. and sometimes 100 over. so I increased the pitch and brought it down a bit. If you need quick acceleration, like pulling skiers, you might need to get a "smaller prop", otherwise I like the higher top end speed.

Here's a discussion on West Marine's page.

http://www.westmarine.com/webapp/wcs...dvisor=266.htm

myles

Mr.Kitch'nPass · 05-20-2003, 02:05 PM

Wow,sensi Im not sure what you mean by center line? I had a 14.25x19 stainless. but only got about 4200rpm.Boat supposed to max between 4400 and 4800. Went to a 14.25x17 and jumped up to about 5300. I think I would like to be about 5000 max so by the time I fill the tank load gear and guys I should be right.They want to have me try a 15.50x17? Sounds like maybe I should put more cup on the 14.25x17 instead

If Im off base here straiten me out [img]graemlins/stupid.gif[/img] Thanks

Leatherneck · 05-21-2003, 01:27 AM

Is that Northriver still kicking your butt. Seem's to be to much boat for you dave.