RE: Prop sharpening & other tips for new boaters  
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RE: Prop sharpening & other tips for new boaters - 2/3/2006 12:46:49 AM   
Ron Olson



Posts: 13209
Joined: 5/10/2002
From: Kalamazoo, MI, USA
Status: offline 		All props have some degree of cup but some add or take away cupping depending on what they want out of it. Think of it as if you were swimming. Cupped hands will help you go faster through the water than if you held your fingers out straight.
There are many different types of cuts. You can cut the tongue area of the blades as some props from the factory can actually slow the boat down. There is back cutting, Barr cutting, named after Stu Barr, Texas cuts, and the list goes on.
If you want to see what effects cutting could do to your props, if you have metal props take a felt-tipped marker or a machinists blueing and paint your props. Where the marking comes off the prop once you run the boat, this is the part of the prop that is doing the work.
If you've seen that Octura has been coming out with a line of "M" series props, these are the ones that have been modified by Octura to remove unneeded prop area.

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       Post #: 26

RE: Prop sharpening & other tips for new boaters - 3/27/2006 7:14:03 PM   
Jbrooks31


 

Posts: 5
Joined: 3/25/2006
From: Noble, IL, USA
Status: offline 		What are some of the advantages / disadvantages between 2 blade and 3 blade props ?

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       Post #: 27

RE: Prop sharpening & other tips for new boaters - 4/21/2006 2:11:21 AM   
tazmaniaboats


 

Posts: 241
Joined: 3/30/2006
From: gharghur, MALTA
Status: offline 		the prop balancer named by ron in the previosly talks is absolutly fantastic i sharpened and balanced 2 props in about 5 hours I prefer stainless to copper props as we race at sea
octura props are my choice but in malta prather are easily found booq
martin

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       Post #: 28

RE: Prop sharpening & other tips for new boaters - 4/21/2006 2:14:39 AM   
tazmaniaboats


 

Posts: 241
Joined: 3/30/2006
From: gharghur, MALTA
Status: offline 		i m not sure but 3 blades are suitable for nitro/high revs motors[quickdraw] 2blade are for general use

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       Post #: 29

RE: Prop sharpening & other tips for new boaters - 4/21/2006 3:12:15 AM   
jetpack



Posts: 1651
Joined: 10/2/2002
From: Portage, IN, USA
Status: offline 		i found twin blade props cavitate more than three blade if you happen to spin out, but give better rpm's. Three blade props on a tunnelhull make it pull around better in a turn, due to the prop walk drag.

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RE: Prop sharpening & other tips for new boaters - 5/21/2006 1:36:57 PM   
piper_chuck



Posts: 7896
Joined: 6/13/2004
From: Pittsboro, NC, USA
Status: offline 		I'm not Ron, but there's a description of cupping, cutting, and other prop mods in the 4th link of the sharpening section in the first post of this thread. So you don't have to scroll to the top, it's here: http://rcboat.com/prop.htm

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RE: Prop sharpening & other tips for new boaters - 7/1/2006 9:05:27 PM   
jetpack



Posts: 1651
Joined: 10/2/2002
From: Portage, IN, USA
Status: offline 		There is something I would like to point out about prop sharpening that maybe some people aren't aware of. This has been a concern of mine for quite sometime now, and maybe other people have encountered it also...but as far as I know of there really isn't a very good cure for and that is the prop fit of the prop on the propshaft.

It is very important before doing any type of balancing to the prop to get a good prop to drive shaft / drive dog fit.

There hasn't been one prop that I have picked up to sharpen and balance that needs help in this department first. If the prop does not bed completely and evenly against the face of the drive dog you will loose most of your efforts in balancing when it comes time to tighten the prop, so be sure you have cleared the corners of the notches and any other places that interfere with a nice, flat fit to the dog!

The spotface on the prop should be automatically square to the bore as this is all machined from the one side, but don't be suprised to find only one side of the spotface touch the dog. I have found this occur on some props also! I guess this is one thing that determines a good prop from a bad prop too!!!

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RE: Prop sharpening & other tips for new boaters - 7/13/2006 3:42:13 AM   
Doubledog



Posts: 1524
Joined: 3/12/2003
From: Hohenfels, Germany , AE, USA
Status: offline 		You're so right there Jetpack. Can't remember the last one I did that slid right on a prop shaft & the drive dog fit perfect. One of my buddies made me a propshaft handle w/dog attached for working them & its become my standard. Fit first, then check balance & start working...

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RE: Prop sharpening & other tips for new boaters - 7/21/2006 9:18:03 PM   
motocoach


 

Posts: 38
Joined: 6/18/2006
From: montgomery, TX, USA
Status: offline 		You guys. Any idea why my berillium copper Prather 1.6*1.4 is beding at the tips? I mean it is basically new, and hasnt hit anything. It does cavitate a good bit in tight corners, and from a stop, so I suppose the cavititation could be causing the tips to bend over backwards. Ideas appreciated.

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       Post #: 34

RE: Prop sharpening & other tips for new boaters - 7/22/2006 4:57:42 AM   
Ron Olson



Posts: 13209
Joined: 5/10/2002
From: Kalamazoo, MI, USA
Status: offline 		Has the prop been overthinned? It's easy to go too far at the tips.
One of the locals here really thins his props and on his .21 'rigger had folded one up. Outriggers do need to have a thicker blade as they have to support weight.
Cavitating is corners means that the strut is a little too high. When the boat leans over, it is brining the prop closer to the surface. People who offset their struts slightly to the right gain 2 things, one is less tilting of the hull from torque ands the other of course is that it keeps the prop planted in more water in the turns.

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RE: Prop sharpening & other tips for new boaters - 7/23/2006 6:50:45 PM   
TwistedLiquid



Posts: 152
Joined: 6/21/2006
From: Andover, KS, USA
Status: offline 		Yes nice info page Chuck....real sweet!!!!!

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RE: Prop sharpening & other tips for new boaters - 7/23/2006 7:06:24 PM   
piper_chuck



Posts: 7896
Joined: 6/13/2004
From: Pittsboro, NC, USA
Status: offline
quote:

ORIGINAL: TwistedLiquid

Yes nice info page Chuck....real sweet!!!!!

Thanks. If you find any errors or think of additions, post them and I'll add them to the first post to make them easy to find.

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RE: Prop sharpening & other tips for new boaters - 8/9/2006 2:53:09 AM   
sowega flyer



Posts: 310
Joined: 8/1/2006
From: Pelham, GA, USA
Status: offline 		Good info. in this thread. Thanks for all of the advice. I am new to the boating scene so I'm trying to gather any and all info I can.
thanks

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RE: Prop sharpening & other tips for new boaters - 1/6/2007 11:02:21 PM   
Shockwaver


 

Posts: 41
Joined: 12/9/2006
From: Davie, FL, USA
Status: offline 		HI GUYS I'm Setting up my first Gas Boat A 50'' Aeromarine Pro Cat I bought a Mod 1 Zenoah No Clutch Boat is Still under construction Does a 270 sound like a good starting point Also what recommendations for 3 bladed prop i'm thinking 6716? Looking for all around proformance Thanks in advance for advice , Sorry about posting on nitro forum Also what do you guys use to bring out the polished look on stainless props

< Message edited by Shockwaver -- 1/6/2007 11:24:36 PM >

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RE: Prop sharpening & other tips for new boaters - 1/6/2007 11:24:30 PM   
Ron Olson



Posts: 13209
Joined: 5/10/2002
From: Kalamazoo, MI, USA
Status: offline 		That's fine as this thread is about props in general whether it's for nitro, electric or gas.
Sorry that I can't help you out with prop choices as I'm just getting into gas boats myself trying to expand my horizons.

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