[Public-list] Hard on the Rocks
JohnI
a30blueteal at gmail.com
Wed Nov 8 20:09:13 PST 2006
Thanks Glenn. In addition to the unknowns of the corrosion, my rudder has a
slight warp, and this combination of factors has me interested in building a
new one. So, I'll be interested to hearing all I can about your project.
On 11/8/06, brooks.glenn at comcast.net <brooks.glenn at comcast.net> wrote:
>
> HI John,
>
> No doubt there are a lot of variables associated with rudder shaft
> corrosion. I suspect people who sail in fresh water all the time, have
> magnitudes less problem with corrosion than boats stored in salt. Also I
> know in earlier years, at least in Alaska, galvanic potential in most boat
> harbors was enormous because of poorly designed electrical systems. 'Hot'
> marinas really eat up prop shafts nuts, wherever I have always been. I think
> Ketchikan harbor once recorded 400 + volts in the water at dockside.
>
> My rudder shafts dissolved over 25 yrs, so it is a slow process. I am
> going to try bonding the gudeon fitting to the existing hull zinc which
> protects the bronze prop shaft housing. Its only a few inches away from
> the gudeon itself. The gudeon now at least has direct mechanical contact
> to my new one piece lowr shaft, and bottom shoe. In the spring I will look
> at it and see if anything is happening.
>
> STill working on last layers of FG on my rudder, so havnt sent any
> pictures or write up yet,,, but will pretty soon.
>
> regards
>
> Glenn
> Dolce #318
>
>
> -------------- Original message ----------------------
> From: JohnI <a30blueteal at gmail.com>
> > Glenn,
> >
> > Thanks for the description. It's reassuring to see that failure of these
> > parts has plenty of warning. I have issues with galvanic corrosion in my
> > location. This past summer I had a prop nut zinc disappear in less than
> > three months, I'm wondering if rudder protection is also a good idea,
> and,
> > if so, what people use for zincs, bonding strategies, etc. I've also
> felt
> > some "fluttering" of the rudder in similar circumstances to those you've
> > described, so it seems a good inspection is in order.
> >
> > John
> >
> >
> > On 11/5/06, brooks.glenn at comcast.net <brooks.glenn at comcast.net> wrote:
> > >
> > > Hi John
> > >
> > > I noticed a lot of play in my rudder, ( original construction from
> > > 1968). Last season there was substantial, hard vibration during
> certain
> > > broad reach angles.This fall, turned into serious thunking below water
> > > line. I figured the rudder had broken loose and was flalling around
> on the
> > > end of the upper shaft somewhow.
> > >
> > > Turns out the pin sitting in the bronze shoe at bottom of the keel was
> > > corroded down to 1/4" minus and the 3/4" gudeon rudder shaft was
> corroded
> > > down to 5/8" and bouncing around inside the gudeon/pintel assembly.
> The
> > > whole thing could move laterally enough to gind up against the
> trailing edge
> > > of the keel adjacent to leading edge of rudder... very discomforting
> noise
> > > whjilst sailing around.
> > >
> > > It appears a lack of cathodic protection on the lower rudder shafts (
> 1 at
> > > gudeon, one at foot in the rudder casting) basically ate away the
> zinc/other
> > > materials within the silica bronze shaft leaving soft crumbly orangy
> copper
> > > residue in the exposed strategic places.. Also the upper shaft leading
> out
> > > of the rudder thru the full to tiller was pitted and corroded in big
> > > bloches, so... out dam spot(s) and new rudder shafting overall. I
> will
> > > certainly put a small zinc on the rudder somewhere and bond it to the
> new
> > > shaft.
> > >
> > > I have a few pictures and some construction details of the original
> lay up
> > > and can send along early next week. Still fiberglassing a new shaft
> into
> > > the foam core of my old rudder...( captured some measurements as I
> autopsied
> > > the old rudder). Would be happy to send along in a day or so.
> > >
> > > Glenn
> > >
> > > S/V Dolce, #318
> > > -------------- Original message ----------------------
> > > From: JohnI <a30blueteal at gmail.com>
> > > > Glen, what was the reason for the rebuild? I would appreciate seeing
> > > your
> > > > writeup along with some pictures. Thanks.
> > > >
> > > > On 11/2/06, brooks.glenn at comcast.net <brooks.glenn at comcast.net>
> wrote:
> > > > >
> > > > > Hi George,
> > > > >
> > > > > Yes, will write it up. I will try to borrow a camera--mine is in
> > > France
> > > > > with daughter at the moment, likely not to come back for a while--
> and
> > > take
> > > > > some shots of the internal construction of the rudder and
> reassembly.
> > > > >
> > > > > Also, my leaking bronze thru hull rudder post/packing nut assembly
> was
> > > > > finger loose and woobly in the hull after I took out the rudder,
> so
> > > pulled
> > > > > it out and rebedded with 5200 and new glass to the hull. I could
> > > include
> > > > > some details of that little routine also.
> > > > >
> > > > > not a big deal but going more slowly than desired, as usual...
> > > > >
> > > > > regards
> > > > >
> > > > > Glenn
> > > > > -------------- Original message ----------------------
> > > > > From: George Dinwiddie <gdinwiddie at alberg30.org>
> > > > > > brooks.glenn at comcast.net wrote:
> > > > > > > Also made some templates to capture the two angles the upper
> > > > > > > rudder stock bends as it lays around the prop apperature
> opening
> > > in
> > > > > > > the top half of the rudder... A local ship yard made a new one
> > > piece
> > > > > > > rudder stock with 1 " silica bronze shafting, based on the
> > > original
> > > > > > > dimensions for around $900-including shaft material.
> > > > > >
> > > > > > Wow! I'd guess cost might be the reason Whitby used separate
> pieces
> > > > > > with no bends.
> > > > > >
> > > > > > If you're documenting this process and want to write it up, I'd
> be
> > > glad
> > > > > > to post it on the website.
> > > > > >
> > > > > > - George
> > > > > >
> > > > > >
> > > > > > --
> > > > > >
> > > ----------------------------------------------------------------------
> > > > > > When I remember bygone days George
> > > Dinwiddie
> > > > > > I think how evening follows morn;
> > > gdinwiddie at alberg30.org
> > > > > > So many I loved were not yet dead,
> > > http://www.Alberg30.org
> > > > > > So many I love were not yet born.
> > > > > > 'The Middle' by Ogden Nash
> > > > > >
> > > ----------------------------------------------------------------------
> > > > > >
> > > > > >
> > > > > >
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