4 blade prop on 2003 df140

[JDB]

Hey, all. Relatively new owner needing a new prop.  Have decided to try the SOLAS Amita 4 (x138x???). The current prop is a 3x14x19, but WOT is only 5400-5500 about 32 mph.  Too low RPM. (It's on a 21 SR skip. Engine height is about spot on, ventilation plate visible, with little splash trimmed out at cruise. Based purely on estimates, it's between 15 an 17 inch pitch.  Do these props run higher than estimated rpm's,  lower?  Additionally, does anyone or anywhere in the south sound or north sound (I don't really do on land anything in that central sound area) have either of these props as a try before you buy?
   BTW, during Salmon for Soldiers 2018 event we made it known to the world that her name is "Bacon".

[AP]

http://www.arimaowners.com/index.php?topic=6882.msg83136#msg83136

[JDB]

Yes, I did read much about others experience, however I was not sure of a direct correlation since this was posted in 2014, and the gear change was in 2007 to 2.59:1.  I wish it were apples to apples, but no mention of gear ratio.  If yours is a 2.38:1: question answered.  Too easy.

[Fisherdv]

Is your current prop SS or aluminum? Typically a 4-blade prop will run about 200 rpms LESS than the same pitch 3-blade due to the extra drag from the 4th blade and better grip. In a 4-blade you may want to go down to a 15 pitch given your numbers. It's ok to be a couple hundred rpms over your motors max rating when running light loads. That way when you are loaded up, full gas, couple well fed buddies, gear, ice, etc. etc, you will be about where you need to be. Expect to possibly try 2 props before you see what works best on YOUR boat. The aluminum 4 blades are relatively cheap @ about $100. But I think your right, a 15 or 17 pitch

[AP]

The numbers I posted were from my 2004 Suzuki df140.

[JDB]

Happy days and jubilations!! An actual as near as can be 1 to 1 comparison.  Thank you AP.

[mustang65fbk]

I have a similar setup to your boat in that I have a 2003 21' SR ST but I have a Honda 130 outboard.  I have a 3 blade SS prop but don't know the other measurements off hand, that being said I can do a max of 35mph at about 5,600rpm at WOT.  It's usually closer to 33mph if I have some weight, people or a lot of gear in the boat but when it's just me it typically will get to the 35mph mark or close to it, especially when it's flat and the conditions are good.  I'd say you're right in the ballpark with where you want to be numbers-wise.  My uncle and I test drove a 2015 21' SR HT that had a Yamaha 150 on it and that thing did 45mph, pretty quick for an Arima.

[JDB]

Oh, yeah...  An update:
4 blade Amita 17 inch pitch. 6000 wot rpm at a typical load with a top speed (GPS) of 28 Knots.
Tested in fresh water, smooth as glass.  Smooth acceleration, minimal bow lift, the boat seems like it levitates to being on plane.
Tested with and without the hydrofoil/tail, it seems to grab the water better in tight turns with the foil on it, than without.  But more testing is in order.