<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Mary,<div><br></div><div>Here are two things I stole off the Internet. The first is a link to an article about building a rudder, but it begins with some ugly pictures of what the inside of the old rudder looked like. The second is an article that describes what's inside a typical fiberglass rudder and how it's constructed around a metal armature. I think it's safe to say your Tuna rudder armature is stainless and that it's been sitting in saturated foam for many years - probably since shortly after launching.</div><div><br></div><div>Draining is a good idea. For one thing, if you catch the water and it appears rusty-looking, the stainless steel is probably deteriorating. But be sure to solve the leaking problem before you reinstall and relaunch. </div><div><br></div><div>On my current boat the rudder post is hollow aluminum tubing and it was originally anodized. Over the years that layer wore off and the post appeared to be pitted where it entered the rudder top. Before a race to Hawaii we removed the rudder and opened it up by cutting rectangular patches out and then carved away the foam. The webbing appeared to be okay, but there was definitely pitting around the shaft from where it entered the rudder down a few inches.</div><div><br></div><div>We cut the rudder post at an angle, inserted a bolt of aluminum and then bolted and welded it all together. Then we re-foamed and patched the fiberglass. You can't tell it's been repaired, but knowing things were okay and that the previously hollow post was now solid made the race the focus and not whether the rudder was going to fall off. By the way, we also had an emergency rudder along that would have steered the boat just in case.</div><div><br></div><div>I suggest you might do a little investigation inside the rudder.</div><div><br></div><div>Pat Broderick, former Tuna<br><div><br></div><div><a href="http://www.instructables.com/id/How-to-Build-a-Sailboat-Rudder-from-Scratch/">http://www.instructables.com/id/How-to-Build-a-Sailboat-Rudder-from-Scratch/</a></div><div><br></div><div><p align="">SOONER OR LATER owners of fiberglass sailboats become interested in
how the rudders on their boats are constructed. Usually this happens
after an owner notices there is water dribbling out of a boat’s rudder
long after it has been hauled out of the water. In the early days of
fiberglass boatbuilding, when most sailboats had full keels and attached
rudders, many rudders were still made of wood. These were constructed
in the traditional fashion and consisted of a row of planks, often
mahogany, joined end to end, usually with internal drift pins that were
fastened to the rudderstock. You never had to worry about these rudders
getting all full of water, but you did sometimes have to worry about the
planks coming loose.</p><p align="">Since the late 1960s, almost all fiberglass boats have been built
with fiberglass rudders. Not all glass rudders are created equal, but
most are built on the same basic principle. Most commonly, the spine of
the structure is a metal rudderstock (also sometimes called a
rudderpost) off of which sprouts a lateral armature that supports the
rudder blade. Traditionally, this armature is welded to the rudderstock
and consists of a series of lateral rods or bars, or perhaps a simple
flat plate. More recently, foil-shaped fins similar to those seen in the
frames of airplane wings have become more common. This skeletal
structure is embedded in a high-density closed-cell plastic foam core,
which is sheathed in a thin fiberglass skin. This composite foam-core
construction is relatively light with neutral buoyancy, which
significantly improves the feel of a sailboat’s helm while sailing.</p><p align=""><img height="387" width="646" apple-width="yes" apple-height="yes" src="cid:3D3AA260-EE8A-41ED-8437-4584414D02D1"></p><p align="">Interior rudder structures</p><p align="">The key variable is the material from which the rudderstock and its
armature are manufactured. If metal is used, the best choice is probably
silicon bronze, but this is rarely seen anymore. Sometimes aluminum or
even titanium are used to save weight, but the most common choice is
stainless steel. We like to think of stainless steel as an “ideal”
corrosion-proof metal, but this is really only true in limited
circumstances. It does resist corrosion well when routinely exposed to
oxygen, but is subject to pitting corrosion when trapped in a
deoxygenated environment, which is just what you’ll find inside a
fiberglass-skinned rudder once its foam core is saturated with water.</p><p align="">Such saturation, unfortunately, is common in any rudder with a metal
stock. The joint where the stock enters the rudder blade is apt to leak
sooner or later, because the three different materials
involved–fiberglass, metal, and plastic foam–all contract and expand at
different rates as the ambient temperature changes. No matter how well
the joint is sealed when the rudder is first constructed, small gaps
through which water can intrude are inevitably created. Knowledgeable
boatowners take this for granted. They assume their rudder cores are
constantly absorbing water and so drill holes in the bottom of their
rudder blades every time they haul their boats in order to let the
moisture drain out. (A better alternative, obviously, would be for
builders to install drain plugs in the first place.)</p><p align="">Another problem with stainless steel in rudders has to do with its
welding characteristics. When stainless steel is welded, the carbon and
chromium in it mix to form chromium carbide. This creates two
sub-alloys–chromium carbide and chromium-depleted steel–that are
different enough in their composition to form a corrosive galvanic
couple within the weld. Insert this galvanically compromised weld inside
a moist oxygen-depleted foam-cored rudder, and it is much more likely
the rudder’s stainless-steel armature will corrode and fail. A
stainless-steel rudderstock is also apt to suffer from crevice corrosion
inside the shaft seal in the bearing where it exits the hull, as this
is another area where water is trapped and becomes stagnant and
deoxygenated.</p><p align="">All these problems can be ameliorated if the stainless steel inside a
rudder is high-quality 316-L alloy. This variant resists pitting
corrosion much more readily than its lesser 302- and 304-alloy cousins.
It also has a lower carbon content (thus the L designation) and is less
compromised when welded. Unfortunately, there is no easy way to
distinguish between alloys. Silicon bronze, by comparison, is virtually
corrosion proof under the same circumstances, unless it is coupled
directly to steel or aluminum.</p><p align="">Rudderstocks can also be fabricated from a composite laminate such as
fiberglass or carbon fiber. The great advantage of a laminate stock is
that the stock and the skin of the rudder blade can be the same
material, which means the joint where the stock enters the blade can be
permanently sealed. Also, the rudderstock can be bonded directly to the
interior surface of the skin, thus eliminating the need for interior
armature to resist twisting loads as the rudder turns back and forth.</p><p align="">Laminated rudderstocks generally must be wider than metal stocks in
order to resist the transverse loads imposed on them. This means the
rudder blade must also be wider, which tends to degrade the rudder’s
hydrodynamic form. One way around this is to flatten the sides of the
stock into a trapezoid shape. This not only creates a narrower
cross-section, but also presents a much larger surface area for bonding
the stock to the skin of the rudder blade. Note, however, that a
trapezoid stock needs bearing rounds installed where the stock passes
through its rudder bearings in order for the rudder to turn properly.</p><p align=""><img height="330" width="649" apple-width="yes" apple-height="yes" src="cid:329FB875-949D-4765-9281-ED57D819F028"></p><p align="">Metal vs. laminate rudderstocks</p><p align="">In practice, unfortunately, fiberglass rudderstocks have not
performed well. Some mass-production builders have embraced them,
because they are cheaper and lighter than stainless-steel stocks, but
there have been several incidents where fiberglass stocks have failed in
moderate sailing conditions. Builders, as a result, are now more wary
of them.</p><p align="">Carbon fiber is another story. Carbon rudderstocks have proven much
more reliable, as carbon is much stiffer and stronger. It is also much
lighter. An all-carbon rudder (i.e., a carbon stock bonded to carbon
skins wrapped around high-density foam) weighs less than half as much as
a conventional foam-filled glass rudder with a stainless-steel stock
and armature, but also costs two to three times more. Carbon rudders
therefore are normally seen only on race boats and high-quality cruising
boats.</p><div><div>On Oct 1, 2013, at 5:37 PM, Mary Falslev wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><font color="black" size="2" face="arial"><font style="BACKGROUND-COLOR: transparent" face="Arial, Helvetica, sans-serif">I managed to take my rudder off today and bring it indoors to dry off before assessing whether a simple repair or a replacement is in order. The good news is the the shaft is not compromised. There is a hairline crack of about two inches in length on the bottom surface of the rudder. I plan to open that up just enough for it to dry out. If it dries, then I hope it can be repaired with a fiberglass patch. Now it is drying out in a spare shower in the house. I would like to hear from anyone else who has every removed or replaced a rudder.</font></font>_______________________________________________<br>Tuna mailing list<br><a href="mailto:Tuna@myfleet.org">Tuna@myfleet.org</a><br>http://myfleet.org/mailman/listinfo/tuna<br></blockquote></div><br></div></div></body></html>