Rudder encapsulation?
Well, I'm just about to give up on antifouling for the rudder. I have a big
SS rudder on the Krogen, and I've tried a couple of metal finishes, both
from Petit with poor success. I did both; the last was their underwater
metal kit. Sure looked promising. I sanded the rudder down to bare metal,
cleaned with a couple of solvents, dried and immediately put on a couple of
coats of their acid wash primer, followed by their overcoat. Then painted
with anti-fouling paint.
At about 9 months, the paint was bubbling up and several patches were just
gone, exposing bright metal. Oh well...
The yard mentioned that they could encapsulate the rudder in epoxy, which
they claim would solve this problem. The antifouling paint would stick
better to the epoxy. Any opinions on this? Is this something I could do
myself while she's out of the water next time? If so, any suggestions on
procedure/materials? Thanks!
Keith
__
I don't suffer from insanity; I enjoy every minute of it.
I have used CPES as a bonding coat for SS and other metals and it works
well, IMHO. I usually apply a couple coats in rapid succession and then
apply the first coat of whatever I am using after about an hour or two, when
the solvents have flashed off but the CPES is still tacky. This should be
superior to coating with epoxy, then washing the blush off followed by
sanding which provides only the mechanical bond while the CPES will actually
glue the finish down.
Good luck,
Bob Lowe
www.MV-Dreamer.com
www.CruisingAndMaintainingYourBoat.com
I have a big SS rudder on the Krogen, and I've tried a couple of metal
finishes, both
from Petit with poor success. I did both; the last was their underwater
metal kit. Sure looked promising. I sanded the rudder down to bare metal,
cleaned with a couple of solvents, dried and immediately put on a couple of
coats of their acid wash primer, followed by their overcoat. Then painted
with anti-fouling paint.
At about 9 months, the paint was bubbling up and several patches were just
gone, exposing bright metal. Oh well...
The yard mentioned that they could encapsulate the rudder in epoxy, which
they claim would solve this problem. The antifouling paint would stick
better to the epoxy. Any opinions on this? Is this something I could do
myself while she's out of the water next time? If so, any suggestions on
procedure/materials? Thanks!
Keith
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At 07:12 AM 06/16/2004 -0500, Keith wrote:
Well, I'm just about to give up on antifouling for the rudder. I have a big
SS rudder on the Krogen, and I've tried a couple of metal finishes, both
from Petit with poor success.
There are two problems that come to mind about epoxy encapsulation of the
rudder.
-
If epoxy really sticks to the submerged stainless, then why didn't it
stick when used as an undercoat for the anti-fouling. You may just get
thicker bubbles and chips (and spend a lot of money on the marina monkeys).
I can tell you that thick epoxy will be worst at sticking to submerged
stainless than thinly applied epoxy. Especially on a large flat surface. -
If you get corrosion under the thick encapsulation you won't see it. If
there is no mechanical trauma to the surface it may not peel but the water
will find a way to get behind it. Stainless corrodes best when water gets
behind the film and has no source for oxygen. It causes pit and crevis
corrosion very quickly in warm water..
Perhaps the failure of the Petit coatings was due to the lack of
sandblasting the stainless. Sanding is generally not good enough. If you
can't blast yourself, spend money on getting the rudder properly blasted
and coated with the Petit system before going the whole encapsulation
route. I bet they blast before that as well, which should be all you need
to fix your trouble.
Another point of failure may have been the application of the etching
primer. I don;t recall two coats but I don;t have the specs in front of me
and they are not on their web page. Etching primers generally go on really
thinly (1mil or even at .5 mil). They are best applied as evenly as
possible and usually show the substrate thru the coating. Then two coats of
epoxy and then your anti-fouling. All with proper dry times. If the flash
or etching primer is too thick it will fail.
Good luck.
Skooch
David Stahl
Beacon Technologies Inc.
Serving The Delaware Valley
Business and Residential Internet Services
Keith and all,
I essentially encapsulated the rudders on the Celestial in epoxy. It was
two part epoxy paint that the boat yard buys in bulk. It is Sherwin
Williams Duraplate 235. It comes in about 6 colors.
It has held up very well on other boats they maintain, including a 60'
go-fast sport-fishermen and even aluminum boats and outdrives. The local
experience is that the prop tips will wear off, but all that has to happen
there to fix it is to add two more coats (not over any bottom paint). The
rudders of the boats I saw had only the bottom paint worn off, showing the
black (top layer on that boat), but no brown at all. I didn't see the props
as they had been removed and reworked. These boats are run hard in the
commercial fishing industry in the northern Gulf of Mexico, mostly out of
Panama City, FL. Removal of all bottom paint is essential, including a good
wipedown with MEK or acetone to remove all oil or other surface
contaminants. The surfaces cannot be left smooth, but instead must be
sanded with about a 60-grit sandpaper, which gives added rough surface for
the paint to stick to.
They also recommended I put it on all the rest of the underwater metal -
thru-hulls, strainers, etc. and running gear, including the props. Be sure
to poke the holes out if painting a strainer! They said that the prop tips
probably will not wear off for several years on the Celestial as I don't
run it anywhere as fast/hard as the sportfishermen. They use two colors to
tell how worn the layers are: one brown and one black. For esthetic
reasons, the first coat is usually brown and the top coat is usually black.
Usual caveats apply - YMMV.
Take care and be safe.
Wayne
M/V Celestial
Albin43 Sundeck
Articles that I have read suggest that epoxy undercoat is essential.
Ron Rogers
Willard 40 Akela (to be AIRBORNE)
Lying Oriental, NC
they claim would solve this problem. The antifouling paint would stick
better to the epoxy. Any opinions on this? Is this something I could do
myself while she's out of the water next time? If so, any suggestions on
procedure/materials? Thanks!
Keith- What process is the yard offering to use to encapsulate the rudder?
The industry that I work in is underground pipe valves and fittings. Soil,
chemicals, water and galvanic corrosion cause a significant amount of
corrosion in the products that we sell. Over the last 15 years, the market
has moved very dramatically to fusion bonded epoxy coating on ductile, cast
iron and steel fittings that are to be buried. The results have been a
dramatic reduction in corrosion in almost any type of soil conditions.
I can't specifically say that you will have the same sucess with a paint on
epoxy treatment, but I am inclined to believe that there are shops capable
of performing a fusion bonded expoxy treatment if you are willing to pay the
price.
Jeff Folino
QEIII- Island Gypsy 32
Clayton , NY