Feathering Props
I chose the Gori 2-blade folder to replace my 2-blade fixed prop. We've
enjoyed a speed gain of close to a knot in light to moderate wind conditions. I
believe the Martec and Flex-O-Fold 2-blade folders
(with geared blades) are quite comparable. I went with the Gori
because some of the reviews I found claimed little or no vibration and that's
also my experience. Didn't think an extra $900 for the 3-blade folder was
warranted in my case. We sail 95% of the time. Installed it
myself with no problem. No modifications or drilling into the prop shaft
were required. Now if someone would just make a prop that barnacles don't like
to call home!
Peter Clancy
AROBAN C320 #222
I replaced the 3 blade fixed
with a AutoStream 3 blade feathering prop on Wind
Dancer 3 or 4 years ago and it has worked out great with better performance
under power or sail. I did not have to
replace the original bronze or brass shaft with a ss as with some of the other blades. I suggest that you visit the Martec website and call the guys at Martec
they will give you the details. I found
that the prices at the Sail shows have been the best time to buy. The only maintenance that you have is to
replace the zinc every year or two and keep it greased, which I do in fall at
haul out.
Ralph Winkler
I decided to go to a folding
prop last year (2004). I looked closely at
Flex o Fold, Martec and Gori. Flex o Fold did not reply to any of my
inquiries on the net, Gori not only replied but had a
representative call me, Martec replied by email. What I found was that Flex o Fold was not
well known here in
As far as performance is
concerned, it has been a major improvement. It works well in both reverse and
forward and I have noted no change in motoring performance. Sailing performance has been enhanced
although I can't quantify it because my knotmeter
hasn't worked since the yard visit. However my racing results have been more
competitive so I attribute part of that to the prop (and part to the new bottom
job).
I agree with Wes in that
everyone seems to agree that all three manufacturers' products work well. I just didn't want to spend the extra money
for a feathering prop as I could not identify a reason to prefer the feathering
prop over a folding prop. Good luck.
Bob Carlson
S/V Adeline
C320 #180
IF... you decide to go with
#1 , AND the Hard your boat is on is really not that
hard, AND either you or your helper can handle a very awkward 75# with
confidence, pulling the rudder is really no big deal. When I did it 3 years ago
to add an AutoProp and replace the shaft with SS I
was lucky enough to be on well packed sand (not the hourglass shifting type).
It took me around 2 hrs to dig the 5-ish foot hole working at a reasonable -
not hurried pace. Measure the rudder and add
the shaft plus 6" or so -
that's why I say 5-ish because I don't remember the exact depth. I'm only 5'
7" and it wasn't over my head.
I went into it with NO forehand knowledge
and sitting here a hundred miles from my boat I can't give you the exact
configuration of the method it is secured except that as I remember the bolt you
see when you remove the deck access port is last thing to remove after
everything else is free - with someone in the hole holding up the rudder. The
sequence went something like - slacken the steering cables on the quadrant,
loosen the quadrant which if I remember correctly is a 2 piece affair that
clamps onto the shaft, then with someone holding up the rudder remove that bolt
that goes through the bearing sleeve and through the rudder shaft. Mine was
only 2 years old at the time but it still took a bit of persuasion/twisting/lifting
up/pulling down etc... before
it broke free. No doubt every rudder will be different - instant release or
having to actually pull down on it. My details may not be correct but the thing
is just not that complicated - look, touch, figure it out and just do it.
When it comes to removing the shaft taking
of the tranny attachment plate may be the hardest
part because of rust. Mine was off when the boat was 6 months old to add a PSS
Shaft Seal so after only a year and a half mine came off with only a little
persuasion needed.
The cutlass bearing that you - Will Be
Replacing - is held in by 2 set screws. It's soft metal and you are throwing it away so while being kind
to your strut the bearing gets destroyed. I think I took the blade out of one
end of my hacksaw, inserted the blade into the cutlass hole, reconnected the
blade to the hacksaw and sawed through the cutlass and
pried it out. To install the new
one I packed it in ice to shrink it every possible micron, heated up that area
of the strut with a small torch (20 degree December day) to expand it every
possible micron, lubed the bearing with soapy water and tapped it in. Then with
locktite tighten down the 2 set screws Only enough to secure the bearing and Not deform it - make
note of the depth of the set screws beforehand. If you don't already have the
cutlass bearing the name is Blackfish or
something weird like that.
Stan
"Christy Leigh"
Wickford/Narragansett Bay RI
I changed to a steel shaft
this spring after bending the shaft twice (or not having it properly
straightened the first time)
I ordered the shaft from Catalina along with a new cutless bearing. If
you caught a line in the prop the bronze shaft would probably be bent where it
exits the strut. A simple way to check
this is to tape a straight edge parallel to the shaft. Rotate the shaft and see if the space
changes. I dropped the rudder. You need space below. I had them put the rudder over a grass patch
in the marina at haul out and dug down about 20 inches. The rudder is held up by two bolts. One under the cockpit sole
opening for the emergency tiller and one thru bolt under the steering quadrant. These came off easily. Not as easy to remove were the four bolts
holding the quadrant onto the shaft. These are apparently stainless on an
aluminum quadrant. Put lots of WD4 or
similar loosening agent on and use a vise grips with a pipe extension if
necessary. The rudder then pulls
down.
Disconnect the shaft
coupling from the engine using spacers, remove the shaft and replace the cutless bearing.
While some have suggested the shaft can be removed without
dropping the rudder, I don't see how even with the bearing removed first. My hull is #249.
What has your experience
been with fouling? We've considered going to a geared folding prop but have
always been concerned that fouling could prevent it from opening properly when
it's needed most. Our boats have had bronze fixed two-blade props on bronze
shafts and in some years the fouling hard and soft) has been bad enough to
really affect performance under power even with fixed blades and require
frequent scraping. When they were still available, the spray paints for outdrives with TBT were very effective but of course are
now banned. Is frequent cleaning the
only solution for you?
David Eusden
C320 #581 "Eiderdown"
Hi David,
I have a Gori
3 blade prop. It's unlikely that growth
is going to stop the prop from opening.
The prop's design makes it hard for it not to open simply due to
growth. Once the prop starts to turn, it
will bite in and all blades will open.
I wouldn't bother with
trying to spray it unless you're concerned about clams or mussles
encasing it. Barnicles
get ground up pretty fast in the gears.
It's a very rugged hunk of bronze. As for the fouling of the blade
itself, that seems not to matter really wither you have a fixed/folding or
feathering prop.
-Jeff
Went out to the Alchemist
last night (raining and 39 deg.) and checked my Gori
2 blade folding prop. It is a 16.5" diameter prop, but I couldn't tell the
pitch. I rooted around through my papers and found the original order, and it
is a 16.5 x 11. That is what Gori recommended.
This prop works great under
the Alchemist (#909) with the European Yanmar 3GM30F,
achieving hull speed at about 2800 RPM (possibly a little less), with no excess
vibration due to the prop tip being too close to the hull. This is probably
because the tip of the prop is further back (about 4 inches) than a fixed prop
would be, thereby giving sufficient clearance.
Steve
Alchemist C-320 #909
After reading everyone's
comments and experience: members who first tried Gori
3-blade size 16-1/2 x11 reported cavitation,
etc., and switched to Gori 3-blade size 15 x 10 which
they say works well on the 320.
The Gori
2-blade size for 320s brought differing opinions. Some members
report 16-1/2 x 11 has been terrific with Yanmar
3GM30F. Some members report 15 x 10 works well with Perkins engine. Some
members feel the 2-blade size Gori recommends for
above Yanmar, 16-1/2 x 11, would be too large and/or
have too much pitch. (Gori now recommends 3-blade
size 15 x 11).
My feeling is to try the Gori 2-blade 16-1/2 by 11. Especially since Steve,
Alchemist #909, has it installed for quite awhile, says he reaches hull speed @
2,800 rpm, runs great with it, and no problems.
Len
Aqua5 #1070
On
(especially down wind) while the drag from the 2 blade is
much less apparent.
It
may have been coincidental, but the top three boats in the '02 C-30 Nationals
had 2 blade Martec folding props, the next three
boats had two blade fixed props, and the last three boats had three blade fixed
props. Even adjusting the elapsed time for the respective handicaps didn't
affect the standings in any of the races.
Steve
Alchemist C-320 #909
Again
this thread comes up along with the groundhogs every spring. This year it is a
bit early.My bottom line is a reflection of the
Practical Sailor research. Autoprop was and is still
rated the best. I have had on for 6 years and I highly recommend it.
The
complete review can be found in the PS Jan 1 1995 article titled "M.I.T. Propeller
Test, Round 2. (Page 5)" This was the second test the first was in October
1993.
You
might contact them at 800.424.7887 and purchase a back issue. If it is out of
print send me $3.00 and I will make a copy.
Autoprop also has an interesting web site with an on-line demo at Autoprop.com
Cheers,
Dick
Walker
C-320
(687) WindWalker II
619.435.8986
Hi
Mike,
I
have a Word document comparing some of the prop manufacturers that you mentioned.
There are comparisons of Autoprop, MaxProp, and Martec by C320 owners.
It used to be on the C320 web site. I can attach a copy of it to an email if
you or anyone else is interested. One piece of information on the Autoprop seems to have changed and that is the original
article
indicated a 16" diameter was appropriate whereas I just received a recommendation
that 15" diameter was recommended.
Rod
Boer
Odyssey,
#688
We
do PHRF and Assigned Rating Class events in
also reported good experience with the Gori
3-blade folder. I believe the 2-blade Flex-O-Fold is quite similar to the Gori.
Peter
Clancy
AROBAN
C320 #222
I love
my Martec 2-bladed folding...best performance
purchase for
Regards,
OD
Looks
like 2-blade folding props, in general, could be getting an unnecessarily bad
rap. I had a Martec, non-geared, 2-blade folding prop
on my prior 31' sailboat for over 15 years. The only time vibration was an issue
was when sea creatures became encrusted on the blades. Once
cleaned, no more vibration. Proper installation is very important to
eliminating
potential vibration. For example, a new prop should be tightly and uniformly
"seated" on the shaft. This is done by rotating it by hand on the fixed
shaft with grinding compound applied to the interface. A worn cutlass bearing
or slightly warped shaft will also allow the slightest unbalance to become a
noticeable vibration. I am of the opinion that a 3-blade folding or feathering
prop is only beneficial to owners who do a lot of motoring in choppy conditions
where an extra "bite" is desired. Otherwise, a 2-blade folding prop
provides the least drag, best sailing performance and lowest cost.
Peter
Clancy
AROBAN
C320 #222
>
Well Adam.... I hate to pour salt into your impending financial wound but the
other Stan also has one sitting in his cellar that I could have packed in with
the Spinnaker I sent you. With all the
negative press on fixed 3 blades I didn't bother to advertize
it with my other sell out items. You should find it smoother than your 2 blade
- just as a 4 blade would be smoother than a 3 blade. Not an opinion - just a
simple fact.
>
As for Power when punching through steep waves you should also feel a
difference. I first pulled it and installed a Martec
2 blade folder >over the winter back in 1999-2000. Over the lonnnggg winter and since I only had the c320 since the
previous August the power of the Martec seemed fine. I got sick of, and worried about, the vibration and
did a
>short
haul to put the 3 blade back on and with only a couple days in between I was
Amazed at the difference when I pulled out of the marina - It was like a power
boat in comparison !! I was sooooo glad that I
>switched
back later that year when motoring all day directly into steep 5 footers to get
down to the 2000 c320 regatta in Stamford that August.
>Of
course the winning boat in light air that I crewed on down there had a Martec 2 blade folder that when I drove it under power I
could also feel the same vibration that caused me to remove mine. And yes, if
you
>have
a good breeze you can still sail at hull speed with a fixed 3 blade easily.
>
The next winter I went with the AutoProp and except
for some strange noises that in 4 years proved harmless I was reasonably
satisfied. My Nauticat also has an AutoProp and I'm glad it does for the power and feathering.
The 'best of both worlds' is expensive but I think some type of folding or
feathering 3 blade is the only way you can hope to achieve it.
>Stan
>(formerly) Christy Leigh
>c320
#656
>Wickford/Narragansett Bay RI