HI Dave,
If you can only get 2600 RPM something is wrong. You either have the
wrong pitch or there is something wrong with the engine (throttle cable,
etc.). If there is black smoke at 2600 RPM it is most likely the pitch.
If the pitch is too great, I'm wondering if the prop is cavitating which
can cause vibration. Also, a 16" diameter sounds large for a 35 MK III.
If the blades swing too close to the hull, that can cause vibration. I
seem to recall that if the blade swings closer than 15% (I think) of the
diameter from the hull that will cause vibration. I had a 35 MK II and a
14" prop was marginal.
Gary
S/V Kaylarah
'90 C&C 37+
East Greenwich, RI, USA
~~~~~~~_/)~~~~~~
On Wed, Oct 26, 2016 at 9:21 PM, Dave via CnC-List <cnc-list@cnc-list.com>
wrote:
> Kevin,
>
> I've struggled with the same issue for three seasons.
>
> When I first got the boat it have a Martek 2 blade folding prop. When
> motoring off the mooring no problem. But after sailing the prop vibrated
> horribly. Throwing it into reverse and then back into forward usually but
> not always resolved the issue. At the end of the season I sent the prop to
> Martek to have it rebuilt. I also had the transmission rebuilt and the cone
> gear replaced. Put the boat back in the water in the spring and found that
> the problem was still there. The following winter I replaced the Martek
> prop with a Flexofold. Lwo and behold the problem is still there.
>
> I made sure that the engine was in alignment and had two boat yard
> mechanics out on the boat. When heading into a 3 knot current there was no
> vibration but when we went perpendicular to the current the vibration
> resumed. This happened repeatedly. The mechanics told be that the vibration
> is typical for a two bladed folding prop. One thing that became apparrent
> during that test was that the maximum rotation I was able to get up to was
> 2600 RPM. The boat has the original Yanmar 3GM30 and Kanzaki KM3-A
> transmission. The gear ratio is not stamped on the transmission but, I've
> been assured that the gear ratio is 2.61:1 and have no reason to believe
> it's not. I purchased the prop recommended to me by Flexofold which is 2
> blade 16x12R. When I told Flexofold about the issue they insisted that
> the prop was the correct one and I do know that other 35 MK3s have had
> success with this same set up.
>
> The Flexofold blades are geared to one another. So, it's impossible for
> one blade to open while the other is not. So, that can not be the problem.
>
> So, any ideas beyond what I've already done are greatly appreciated.
>
> Dave J
> Saltaire
> C&C 35MK3
> Bristol, RI
>
>
> ------------------------------
> *From: *"John and Maryann Read via CnC-List" <cnc-list@cnc-list.com>
> *To: *cnc-list@cnc-list.com
> *Cc: *"John and Maryann Read" <johnpr...@comcast.net>
> *Sent: *Wednesday, October 26, 2016 7:18:44 AM
> *Subject: *Re: Stus-List Folding Prop won't open
>
>
> Ditto to Dave’s comment. Our Yanmar 3GM is mounted to a Kanzaki
> transmission that was slipping. Symptoms were prop did not open
> symmetrically because was not spinning enough so lots of vibration, when it
> did fully open the shaft was not spinning at a rate consistent with the
> throttle. No obvious issues with the prop manually opening when hauled.
> Pulled transmission, got it rebuilt. Biggest expense was OEM rebuild kit
> and needed new cone gear as was polished. Reinstalled and problem solved.
> When reinstalling it is very important to ensure the shift cable is
> adjusted so the transmission lever is fully engaged before the lever on the
> binnacle is at the end of its travel – ie there is some remaining movement
> for the spring fitting that attaches the cable to the transmission lever.
> In our case that meant attaching to the inner transmission lever hole.
> Also, an annual maintenance item is to oil the spring fitting.
>
>
>
> FWIW, here is the info on my rebuilder. He is the person who did all the
> transmission work for Mack Boring when they were in the business of
> rebuilding and apparently there are some tricks of the trade to correctly
> rebuild. Shipping was by parcel post, he was very informative and easy to
> work with. I had the unit returned to me in 7 days. No affiliation just a
> happy customer.
>
>
>
> Rick Neary
>
> East Coast Marine Transmission
>
> 253 Vineyard Ave
>
> South Amboy, NJ 08879
>
> 732-991-0694
>
>
>
> John and Maryann
>
> Legacy III
>
> 1982 C&C 34
>
> Noank, CT
>
>
>
> *From:* CnC-List [mailto:cnc-list-boun...@cnc-list.com] *On Behalf Of *Dave
> S via CnC-List
> *Sent:* Tuesday, October 25, 2016 11:02 AM
> *To:* C&c Stus List
> *Cc:* Dave S
> *Subject:* Stus-List Folding Prop won't open
>
>
>
> Make sure it's the prop. I threw a ton of money at similar symptoms
> before learning that the transmission was slipping. (bang bang bang in
> forward only, and intermittently, though progressively less so.)
>
> Pulled the gearbox and did the repair myself in an evening for less than
> $100 after replacing a lot of stuff.
>
>
>
> Dave.
>
>
>
>
>
>
>
> Message: 1
> Date: Tue, 25 Oct 2016 11:43:15 +0000
> From: Kevin Paxton <kpax...@paxdesigns.com>
> To: cnc-list@cnc-list.com
> Subject: Stus-List Folding Prop won't open
> Message-ID:
> <CAOkrQryaXXAxcfeR76uUYBkNZaoGFKFyDz-tKtoMMg+pcYsFaA@mail.
> gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Hey guys, with all of the discussion on props it reminded me that I'm
> having an issue with my 2 blade folding prop. Pretty sure it's the Martec
> that you all are mentioning.
>
> I continue to have issues with one blade not opening after we've been out
> sailing. Once we drop the sails and go to engage the engine and prop it
> fails to open one side and I get severe vibrations. Is this a normal thing
> with these props? It truly makes me want to just get a fixed prop.
> Unfortunately that's not in the budget right now though.
>
> So far I've tried:
>
> - to come to a complete stop and try again
> - Kick it into reverse and then back to forward
> - short kick to full throttle.
>
> The last time we were out nothing worked. We ended up limping along back to
> our slip. Afterwards I checked it by rotating it from the inside and it
> sounded like both blades would open when it was facing down because I heard
> the clunk.
>
> Occasionally it will open but it's not a first time thing. On departure
> from the slip I don't have any issues, it's only when trying to reengage
> the motor after a sail. It's really frustrating, any ideas?
>
> Kevin Paxton
> '82 34 #473
> Japhys Spirit
> Cornfield Creek, Magothy River, MD
>
>
> _______________________________________________
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> _______________________________________________
>
> This list is supported by the generous donations of our members. If you
> wish to make a contribution to offset our costs, please go to:
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> All Contributions are greatly appreciated!
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