The owner of Mea
Culpa has a passion for fishing and we are truly touring the
world and enjoying game fishing along the way. While fishing our
way through the Pacific we learned that carbon fiber propellers
were originally
designed and built for nuclear submarines. One
company is now designing and building such props for game
fishing boats and yachts.
 Upon
further investigation we contacted Contur Propellers in Florida
and asked if they could
design and build some new props for the
Mea Culpa. We were told that carbon fibre propellers would
provide some significant benefits such as fuel savings when
under way, less propeller noise, less vibration, much less
weight and the ability to ‘get home’ in the event of striking a
submerged object while under way. Just how true these claims
were had yet to be seen.
Cavitation seemed to be the biggest detriment to the propellers.
We had witnessed high-speed game boats doing 35–40 knots and
having so much cavitation that the surface of the propeller
could not withstand it. However, with a 130ft motor yacht that
does 21 knots, cavitation was not an issue, as we were not
planing.
During construction of the propellers, ABS witnessed the entire
process of building the carbon propeller blades over titanium
inserts that fit into the milled bronze hubs. Destructive
testing was performed and
AIR Technologies did a fantastic job
with this process. The props were delivered in wood crates, and
as we happened to be doing a shaft survey we therefore
‘blue-fitted’ the new props to the shafts. All went smoothly.
 On
the first sea trial we noticed the following: across the board
we had a 1-knot increase in speed at the same RPM, with the top
speed now 22.5 under full load. Our McMullen & Wing yacht had
experienced no vibration issues, no noise issues and the boat
was fishing very well. On this sea trial, however, we found out
that the new Contur Propellers had taken away the minute
vibration and noise that is caused by turning two 50” (1,270mm)
propellers with 52” (1,320mm) of pitch. Wow, what a difference;
I couldn’t wait for the owner to experience the ‘new’ boat!
We saved a ton (literally) of weight, we increased our speed,
increased our traveling range at 1,070rpm, and
cut down
propeller noise and vibration, thereby increasing our
fish-ability. We also added safety to the vessel without even
knowing it.
This brings me to a story that most captains don’t really want
to tell: we had just completed a total refit paintjob at
Rybovich in West Palm Beach using the new DuPont Marine Imron
paint and were proceeding to a sea trial, when the unexpected
happened. We hit a submerged object in the harbour while
traveling at a slow speed. Immediately stopping the yacht after
impact we then tested the propulsion and found that it worked.
Our chief was standing in the cockpit and reported that no
vibration and no noise could be felt when I went in and out of
gear. I tested the maneuverability during the trip back to the
shipyard and found that maneuverability was intact. We transited
the channel, turned around and backed into our slip.
We then dove down to discover that about 5” (130mm) of all 10
blades were completely missing from the carbon props. Even
though we had literally destroyed the tips of the blades, we
were still able to maneuver the boat safely. Our props are
deeper than the keel, stabilizers or rudders and therefore were
the only thing that was struck.
Upon hauling out to observe the damage and put on a
spare set of
bronze props, we found no further damage. The rudders had not
been touched; the stern tubes were perfect; the ‘A’ bracket
showed no signs of any stress; the shafts were spun and tested
with a micronometer and showed that they were still ‘true’ and
the transmission and gearboxes again were in excellent
condition. The only damage was that our propellers had been
reduced in both diameter and pitch, yet were allowing me to
operate the vessel with the same precision that I did when they
were first installed.
 While
we were building Mea Culpa we made plans to travel to
some remote areas in the world where charts were not always
accurate in search of fish, beaches and adventure. Others can
attest to the fact that had this same scenario occurred with the
bronze props that again all 10 blades would have been mangled
(but would have remained attached), and shaft, stern tube,
perhaps gearbox and transmission would have sustained damage as
well. For certain there would have been tremendous vibration and
noise, and maneuverability would have been greatly reduced, if
it were even possible to move under our own power.
The bronze hubs were sent back to the factory which built new
blades and set up the props again for our reinstallation. I’m
very proud to report that we have our Contur props back on and
clocked 24.9 knots on sea trial under lightship conditions,
again with no vibration or noise.
Our next trip is wahoo fishing in the Turks & Caicos Islands and
we’re headed there with the knowledge that should an unplanned
impact with a submerged object on the props we will be able to
safely navigate and not be stranded. I cannot say enough good
things about the benefits to a super yacht and challenge you to
investigate the benefits for your own vessel.
The
cost of these carbon propellers is similar to that of
conventional bronze props. For a
competitive bid or price
indication anyone can contact
Mel Katzen of Contur Propellers. If you mention this
article, he will extend a $500 discount on an order. I can
be reached at
heinllc@aol.com if further comment or information is
requested. Good sailing!
(We would rarely allow these previous sentences but since it is
an unsolicited and enthusiastic testimonial and there is a
potential deal for our readers it seems justified – Ed.)
Mike Hein
Images: Mike Hein and courtesy of DuPont Marine, Oscar Arellano,
Juerg – Fotopress
To comment on this article, email
issue106@synfo.com with subject: Why Carbon Props? |
