[C38] 3 bladed folding prop

Tue May 28 15:26:54 EDT 2013

In case you haven't seen it, here is a link to an article on propeller
tests conducted by Yachting Monthly in 2009.

http://www.flexofold.com/upload_dir/docs/Test_YachtingMonthly_low.pdf

I ended up getting a two-bladed Flexofold.  In calm conditions it actually
pushes the boat faster than the previous fixed three-bladed prop (with the
same pitch) at the same engine rpm.  Presumably that's because of the nice
blade shape (much much nicer than a Martec, and more effective than the
symmetric blades used on feathering props).  However, I imagine the Martec
has slightly lower drag when folded.  I have not noticed a vibration
problem.  I think that is more significant when the propeller sits right
behind the keel, as oppose to the more open location on the C38.

Compared to a three-bladed prop, you do give up something when motoring
into wind and waves.  Here's what Flexofold said about it.

"One would choose a 2-blade propeller because, in flat water, it will reach
a higher speed for any given RPM.  It will also have lower drag under sail
and will cost less.  The 3-blade Flexofold will perform better in maneuvers
around the docks, in forward and reverse, will attain a higher average
speed against a head sea, and will stop the boat quicker.  The 3-blade may
also be a little smoother running if there is a problem with vibration. The
choice of 2-blade vs. 3 blade is really up to your personal preferences."

Note also that their recommended 3-blade prop had a lower pitch than the
recommended 2-blade prop.

two cents,

Ray Torok

On Tue, May 28, 2013 at 10:38 AM, Max soto <maxsoto at gmail.com> wrote:

> Steve O, that's the case for the Max Prop Classic only, with the new MP
> Easy, the prop will work with the  SAE thread on the shaft. Also, it can be
> installed by a diver very easy, don't need to haul   out, even changing the
> pitch can be done by replacing a couple of screws under water, without
> having to haul out and disassemble the whole prop.. It's a few bucks more
> expensive, but totally worth it. What convinced me to buy this prop is that
> If something goes wrong, you'll be able to replace it in the water for a
> fix prop with a standard prop puller (not the case with the classic).
> Still having problems with the new engine, so this prop has been stored
> for a year....... Hopefully in a few months will be installed and spinning
> proudly on Estancia..
> Hope this helps!
>
>
> Max Soto A.
> +506-8312-1367
> Alajuela, Costa Rica
>
> On May 28, 2013, at 10:27 AM, S Orton <ssorton at hotmail.com> wrote:
>
> Steve S  What turned me off the Max Prop was the installation instructions
> to trim off the end of the shaft (a few threads).  After doing this do you
> have any problem re-installing the Martec?  At this point I want to keep
> the ability of using my existing 2 bladed geared prop for future racing.
>  What life do you get from your cutlass strut bearing?
> Cheers, Steve O
>
> ------------------------------
> Date: Mon, 27 May 2013 21:28:36 -0700
> From: SSmolinske at rainierrubber.com
> To: listserve at catalina38.org
> Subject: Re: [C38] 3 bladed folding prop
>
> Steve,
>
>
>
> I have a three bladed max prop I switch out for cruising, we race with a
> two bladed martec.  The max prop is amazing there is no vibration, lots of
> power and she backs out straight.  I love that prop.  It is feathering, but
> because you have three fins even when feathered you will get some drag
> especially as the boat pitches, two of the blades will provide resistance
> through the water as the stern goes up and down, still better than a fixed
> prop and, If that bothers you Max prop also makes a two blade version.
>
>
>
> Steve
>
> #312 Peregrine
>
> Seattle
>
>
>
> *From:* listserve-bounces at catalina38.org [
> mailto:listserve-bounces at catalina38.org <listserve-bounces at catalina38.org>]
> *On Behalf Of *S Orton
> *Sent:* Monday, May 27, 2013 5:23 PM
> *To:* Cat 38
> *Subject:* [C38] 3 bladed folding prop
>
>
>
> Has anybody tried a 3 bladed folding prop?  Slipstream makes a geared 3
> bladed folding prop which should have less drag and be more efficient than
> a feathering prop.  I've got to go to a three blades to reduce vibration
> and to make my cutlass bearings last longer-now a geared folding prop is
> installed.  I typically replace the cutlass every time I haul the boat.
>  Phil Gay tells me he hasn't replaced his cutlass since replacing his prop
> with a Max Prop and that was over ten years ago.  What kind of life are the
> members experiencing?  In the past, I removed the shaft took to a machine
> shop to inspect for trueness- the machinist did face the flange while
> mounted on the shaft less than .002", which didn't help.  I have also
> replaced engine mounts.  All alignment procedures were done on the hard.
>  The only thing left is to do is an alignment check in the water.  Or again
> maybe its the 2 bladed prop!
>
> Comments please,  Steve O (Santa Susanna,304)
>
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