Re: Stus-List tip clearance

Tue, 12 Feb 2013 18:00:13 -0800

I have a two blade MaxProp as do many East Coasters who race.  I am into my 5th year with it.  Much better braking than the Eliptic folding prop.  Much better forward thrust also, but not as good as a three blade would be, especially against headwinds and headseas, but I have no regrets.  I have no additional vibration from the prop, powering her, in fact it is less than the normal vibration when she idles.  I don't think a strut disturbs the water as much as keel aperture.  Did have a nasty vibration once that convinced experts that I needed new motor mounts.  I got new mounts and during the change, I discovered the exhaust hose had a little kink where it turned 90 degrees after the exhaust/injector.  The hose had slid against a bulkhead and moving it 1/2" aft, eliminated all of the vibration and my worries.  The exhaust hose caused the vibration throughout the whole boat, causing hatches to rattle. 

Moral:  Check your hose.

Chuck
Resolute
1990 C&C 34R
Atlantic City, NJ
From: "Bill Coleman" <colt...@verizon.net>
To: cnc-list@cnc-list.com
Sent: Tuesday, February 12, 2013 6:18:52 PM
Subject: Re: Stus-List tip clearance

I think it is partly the rectangular shape, and somewhat the not-so-aerodynamic curves on those, if I remember right, and I think a big part is having  blade hitting the disturbed water behind the strut.  If you have half your prop smacking disturbed water, vs. a three blade where it is split up, it is more of a shock every revolution.   It seems to affect some boats more than others.  .  That is the reason I went to the 3 blade Gori.

If I wasn’t racing I would have done the 3 blade FlexOFold.  I might still.

 

 

Bill Coleman

C&C 39 animated_favicon1

 

From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Chris Tassone
Sent: Tuesday, February 12, 2013 5:33 PM
To: cnc-list@cnc-list.com
Subject: Re: Stus-List tip clearance

 

Hi Eric,

When I broke a blade on my 2-blade fixed prop, I bought a Gori 2-blade 16.5x11 RH for My 1979 C&C 34.  I bought a new shaft, coupling and cutlass to complement the Gori.  From 3 to 5 knots I get a lot of noise/vibration.  At 6 knots it is better but still noticeable.  After haulout I spoke with Geoff at AB and they finally agreed to rebalance it.  I put it back on an there was no improvement.  I saw Steve from AB at the Strictly Sail Chicago show last month and he questioned my tip clearance.  I measured it at 5" from the hull.  Steve's response was to have it rebalanced again.  At this point I can't live with this prop and am considering going back to a fixed blade.  I spoke to the people at Flexo-Fold and they believe the problem is the rectangular shape of the Gori blades.  They could be right but I'm a little gun shy regarding folding props.

Chris

----- Original Message -----

From: Eric Baumes

Sent: Monday, February 11, 2013 9:25 PM

Subject: Re: Stus-List tip clearance

 

Chris,

 

What model do you have?

 

I just yanked my Gori 2-blade prop off my 34/36. I put it on last year and when it first went on the boat shook like crazy. I got 100 yards out of the marina, throttled up then turned around. The yard hauled the boat, check the shaft for true, put it back in the water, aligned the engine, drove it, aligned the engine again. 

 

I picked the boat up as the racing season had started, and took the boat 9 hours to a regatta. On the way home I brought it back to the boat yard as the vibration was still bad except for a few RPM bands. I talked with AB marine and they didn't have a 1 1/8' hub but swapped out the blades. The boat came out of the water, blades swapped and went back in. It was better, but when I took the boat out on a cruise, I found the vibration/noise and the complaint of my wife who sleeps in the aft cabin when I leave anchorage early that it was much louder than last year.

 

As I said, I had the yard pull the prop and I am going to contact AB Marine this week. Given everything I went through last year, I am really tempted to just get a martec. If they tell me the prop is fine, then I don't want to put it back on the boat. If they tell me it had to be balanced, I am not sure I trust putting it back on the boat.

 

Eric 

34/36 #74

On Fri, Feb 8, 2013 at 7:55 PM, Chris Tassone <ctass...@charter.net> wrote:

Steve,

Thanks for getting back to me.  I doubt getting this Gori 2-blade 16.5 x 11 RH  prop rebalanced will help since I already did this and the results we're negative.  After trying to resolve this for the last three years I think the only solution is a new prop.  I relied on your company's expertise to size this prop for me and I made a mistake that I will have to live with.  If you know of anyone that wants to buy a prop please let me know.  Thanks for your concern.

Chris

----- Original Message -----

Sent: Friday, February 08, 2013 12:22 PM

Subject: Re: tip clearance

 

Dear Sir,

 

Perhaps the thing to do is have the propeller removed and re-balanced as i think you have enough tip clearance and don't see this as an issue.  Sorry that i cannot be more helpful than that.

Regards, Steve Armitage

AB Marine, Inc

747 Aquidneck Ave

Middletown, RI 02842

 

On Sat, Feb 2, 2013 at 4:58 PM, Chris Tassone <ctass...@charter.net> wrote:

Hi Steve,

My name is Chris Tassone.  I spoke with you at  Strictly Sail Chicago concerning the noise I get with my Gori 16.5" x 11 x 2rh prop.  You suggested that tip clearance could be the culprit.  My tip clearance is 5-1/2".  I spread the prop by spanning the blades and hub with a strait edge and measured this distance.  I also measured the distance on my 1" shaft from the cutlass to the front of the prop hub which is 1-3/8".  My boat is a 1979 C&C 34 with a Yanmar 2QM.  The noise is really noticeable and could be a concern if I ever try to sell the boat.  Would a smaller prop solve the problem?  I installed a new shaft and coupling when I purchased the Gori.  I lapped the shaft and checked it with a dial indicator.  The shaft is aligned.  I really appreciate your attention.

Thanks,

Chris Tassone

 


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