|
SWEATING THE SMALL STUFF
Or you could call this "how to make
your boat cost you thousands of dollars to fix without really trying"! If
you are into some reading, I am building this page to help you find and fix the
things a good surveyor is looking for and you should try and repair while
it may still costs you very little in time or money. I will try to explain
the what, where, and why, of some of the usual issues surveyors see
on boats. Some of these issues are so common, it's like a built in
repair persons or company's future revenue. "Small Stuff" because it
starts with a hole that needs 7 cents of sealer, a 40 cent shiny screw, a 9
cent wire tie, etc.
 VS 
"Composite" Construction
You would think that since it's 2005, fiberglass boats are built
better now than they were decades ago, wouldn't you? Construction methods and
innovations have leaped forward dramatically in just about all things man made.
A well laminated cored panel in a lab environment is a thing to behold, NASA
does it all the time. Boat builders? It may not be rocket science but I believe
that in those labs, we would also be awed. The problem is that the naval
architect and engineers do not assemble that boat using those remarkable
"composites". The technology wanders its way out the lab door to the management
office, the purchasing department, the accounting department, the marketing
department, then maybe the production supervisors, then the shop floor, if
there is no one else in the chain of command! Possibly the same happens in your
business. That's the way of today's business world. America's Cup and those "around
the world race vessels" take advantage of these innovations, those boats are
built to the edge of the material and design envelope by craftsmen. So, what
happens in the production boat market may not even be close!
It turns out that "composite" or cored hulls and decks sometimes
became a method to cut material and production costs. Boats look great, are
lighter thus move faster with power or sail, have extraordinary maneuvering
capabilities, but in reality start to fall apart before they leave the factory!
Core bonds in the laminate are non existent, structural integrity was
compromised, avenues for water to get into that composite exist, and then
the boat is put into the water! All cored boats from all production lines? No,
I do not believe that's the case at all. Although surveyors talk about certain
production power and sail vessels that have historical problems that most
surveyors know about and look for. Plus, some small boat builders have made
excellent cored boats; they have the technology and they have the craftsmanship.
After the vessel is launched is sometimes where the problems start,
even on well made cored boats. Adding hull and deck fittings and attachments
improperly, can start a process that in a few years can make a boat downright
unsafe. The worse offense can be as small as drilling a ¼" hole
through the gel coat into the core without sealing it properly. Simple as that!
Water "wicks" in and constantly travels through the core as it soaks it. That
maybe all that happens, you end up with a heavy, water soaked core. Maybe it
gets worse, the core rots like wet cardboard and the bonds disappear,
structural integrity is now compromised.
I know this sounds strange but brand new
production boats could use surveys. Who else checked the hull and systems but
the builder! Are all those stanchion bases bolted to the deck really sealed?
Water may just sit in areas on deck for months on end. Are the
port light and porthole frame cut-outs been glassed? Are there unfilled holes
in the stringers? Can you see the bulkhead tabbing? Like I said, that 1/4" hole
drilled in the wrong place and not sealed properly can cost you in
the long run.
Maybe it's a good time
to look a little closer at those bolts and screw heads you see on
the deck and in the bilge. Does it have a rust stain trail? If it does, more
than likely it needs to be resealed, maybe even replaced; water will get
into the laminate and composite. As for the chlorides in
salt water, well those chemicals eat stainless steel.
Stainless Steels
The basic resistance of stainless steel
occurs because of its ability to form a protective coating on the metal
surface. This coating is a "passive" film which is resistant to
further "oxidation" or rusting. The formation of this film is
instantaneous in an oxidizing atmosphere such as air, water, or many
other fluids that contain oxygen. Once the layer has formed we say that the
metal has become "passivated" and the oxidation or
"rusting" rate will slow down to less than 0.002" per year (0,05
mm. per year).
Unlike aluminum or silver this passive
film is invisible in stainless steel. It is due to the combining of
oxygen with the chrome in the stainless to form chrome oxide which is more
commonly called "ceramic". This protective oxide or ceramic coating
is common to most corrosion resistant materials.
Halogen salts,
especially chlorides easily penetrate this passive film and will allow
corrosive attack to occur. The halogens are easy to recognize because they end
in the letters "ine". Listed in order of their activity they are:
fluorine, chlorine, bromine, iodine and astatine. These are the same chemicals
that will penetrate Teflon and cause trouble with Teflon coated or encapsulated
O-Rings and/ or similar coated materials. Chlorides are one of the most common
elements in nature and if that isn't bad enough they are also soluble, active
ions; the basis for good electrolytes, the best conditions for corrosion or chemical
attack.
Stainless Steels are iron-base alloys
containing Chromium. Stainless steels
usually contain less than 30% Cr and more than 50% Fe. They attain their
stainless characteristics because of the formation of an invisible and adherent
chromium-rich oxide surface film. This oxide establishes on the surface and
heals itself in the presence of oxygen.
Some other alloying elements added to enhance specific characteristics
include nickel, molybdenum, copper, titanium, aluminum, silicon, niobium, and
nitrogen. Carbon is usually present in
amounts ranging from less than 0.03% to over 1.0% in certain martensitic
grades. Corrosion resistance and
mechanical properties are commonly the principal factors in selecting a grade
of stainless steel for a given application.
 
Technically, stainless steels are commonly divided into five groups:
Martensitic stainless steels are
essentially alloys of chromium and carbon that possess a martensitic crystal
structure in the hardened condition. They are ferromagnetic, harden
able by heat treatments, and are usually less resistant to corrosion than some
other grades of stainless steel. Excess
carbides may be present to enhance wear resistance or as in the case of knife
blades, to maintain cutting edges.
Ferritic stainless steels are chromium
containing alloys with Ferritic, body centered cubic (bcc) crystal structures.
Chromium content is typically less than 30%.
The ferritic stainless steels are ferromagnetic. They may have good ductility and formability,
but high-temperature mechanical properties are relatively inferior to the
austenitic stainless steels.
The more important stainless for boat is
the 300 series. Austenitic stainless steels have an austenitic, face centered
cubic (fcc) crystal structure. Austenite is formed through the generous use of
austenitizing elements such as nickel, manganese, and nitrogen. Austenitic stainless steels are effectively
nonmagnetic in the annealed condition and can be hardened only by cold
working. Chromium content typically is in the range of 16 to 26%; nickel
content is commonly less than 35%.
Duplex stainless steels are a mixture of
bcc ferrite and fcc austenite crystal structures. The percentage each phase is
a dependent on the composition and heat treatment. The primary alloying
elements are chromium and nickel. Duplex
stainless steels generally have similar corrosion resistance to austenitic
alloys except they typically have better stress corrosion cracking resistance.
Precipitation hardening stainless steels
are chromium-nickel alloys and may be either austenitic or martensitic in the
annealed condition. In most cases,
precipitation hardening stainless steels attain high strength by precipitation
hardening of the martensitic structure.
So, what has all this to do with boats?
Plenty, one of the biggest discoveries of counterfeit products in the late 90's
was by the U.S. government in their inventory of nuts and bolts at government vehicle
and aircraft repair centers! They found
all kinds of fasteners that were counterfeit in grade and substandard
materials, etc. What makes you think your stainless supplier hasn't bought them
also? I have come across lots of rusty "stainless" screws and bolts that are
also magnetic (high carbon content) on fittings exposed to saltwater and the
elements. 316 stainless steel is not magnetic, so when you standing there
rummaging through a bin full of screws for that new fitting you're going to
install on deck.
First bring a magnet. All the ones that stick to a
magnet, you do not want no matter how stainless they look
Second,
ensure that fittings and the fasteners will carry the load you will place on
it.
Go to this Aussie website to check the strength of the fasteners,
http://www.marfas.com/mechanical.html
And this one to find
out how tight to make them.
http://www.marfas.com/Ttorque.shtml
Third put lots of
good quality marine sealer in that hole, on the threads, etc., You can clean
off the excess and be sure your not starting a disaster that may cost you
thousands later.
Fourth, if you have
a screw, bolt, or nut that constantly seeps out a rust stain, pull it out and
check it for water intrusion(not caulked properly) and advanced corrosion( old,
rotted, and it maybe failing, fast).
Fifth, read the
labels on the cleaning products you are using; remember all those chlorides in
nature eat stainless, so why would you want to add more.
Lastly, if that stainless fitting passes
all the above checks and it still "rusts" what could have happened is that it
got contaminated! Either in the manufacturing process, the shipping and
handling process, or maybe even in the haul-out yard. Where you downwind of a
steel hull sandblast job or did you at one time try to wire brush that
stanchion base, shaft, etc., with a wire wheel? Chemical cleaning with the
correct chemicals is a must to strip stainless steel of surface iron
contamination no matter how it got there.
Taking care of all those fasteners aboard
cuts down the failure of systems, enhances appearance and value, and makes that
end of the day clean up lots faster.
WIRES
Did you get a good
deal on that nice, shiny, brown copper wire at the auto part store for your
boat? I'm sorry to tell you, it just won't last! The copper will be attacked
before you crimp the first fitting, then voltage and amperage drop,
then maybe corrosion to the point that the wire drops off the terminal and
worse case, falls into the bilge. Now, a possible hot wire in water in the
bilge starts eating metal, any kind of metal. Engines, shafts, props,
thru-hulls, hose clamps, etc. wherever the path of least resistance goes.
Generally speaking, improper wiring on
boats abounds. The marine environment is a harsh one, and what may have
sufficed on an automobile you tinkered with at one time, is no match for the
incessant ravages of the salt water environment. This is especially so on older
boats where multiple layers of electrical upgrades left by multiple owners can
leave an owner perplexed.
And always make sure that you use marine-grade
materials. Marine wire has flexible,
multi-stranded, tinned copper conductors. Tinned refers to the
silver color coating that protects the wire from corrosion. Marine wire
insulation should additionally be oil, water, and heat-resistant. Wire
connectors should be double crimp, tinned copper, with a nylon (not vinyl)
outer sleeve. Do not use wire nuts or simply twist and tape wire ends together.
These methods cannot properly seal the connection, and can vibrate loose,
leaving a live wire out of sight just waiting for something to send it arcing.
Solder can be a mixed
blessing. Solder and tape connections that don't use mechanical connectors can
fail by breaking. A good solder joint is nearly perfect. A bad one can fail
completely. On tinned marine grade wire, excellent, reliable, repeatable
splices can be made without soldering.
Adhesive-lined
heat-shrink tubing is the marine electrician's secret weapon. Properly
applied, this stuff will seal out 100 percent of the moisture in a splice.
Additionally, it also makes it even harder to pull the splice apart. Beware
of thin walled heat shrink tubing that doesn't come with an adhesive. These
products will wick in moisture, and are easily damaged.
  
Butt Splices. You should cut and discard about
two inches of wire to give you a new end to work with. First, strip off the
length of insulation that will fit into the copper barrel of the butt
connector. Use proper wire strippers that remove only the insulation and not
the wire strands with it. Next, find the suitably sized nylon coated butt
connector for the splice. Yellow is for size 10-12 AWG (American wire gauge),
blue is 14-16 AWG, and red is 18-22 AWG. Slide the wire into the connector,
making sure no strands are pushed back. The stripped portion of the wire should
insert completely into the narrow section of the metal barrel. The nylon sleeve
and the wider portion of the barrel should overlap the insulation of the wire.
Making sure the wire does not lose this position, crimp the inner narrow barrel
first and then the outer wider portion. The crimping should be done with very
firm pressure.
Before adding the second wire to the
splice, prepare it for the moisture seal. Use a piece of heat shrink that is
the proper diameter to freely slide over the connector. Cut a piece long enough
to cover the entire splice and overlap the wire insulation by at least a
half-inch on each end. Slide the heat shrink over the wire and out of the way of
the butt connector. Strip the end of the other wire in the connection. Insert
this second wire into the barrel and crimp the connector. Test the connection
with a very firm pull. It is better to have to re-splice it now rather than
have the connection fail in service. Now slide the heat shrink back over the
splice. Using a heat gun, heat the splice evenly by moving the heat source back
and forth and around the splice. Once the tubing has shrunk to taken on the
shape of the splice and the wire, and the adhesive has flowed out completely
around both ends, the splice is complete.
Terminals. The best
terminal ends are the closed ring type, which can't vibrate out if the terminal
screw loosens. The screw or stud must fit in the ring. If the ring is too
large, you will not make good contact, which is what all electrical systems are
based upon. If the ring is too small the screw will bind in the ring. Avoid
using plug in type male/female connectors. These are referred to as blade or bullet disconnects. These are difficult to seal and they often come apart too easily.
Crimping the terminal
end is similar to a butt splice. Strip the wire back the same length as the
small section of the barrel plus another 1/16 of an inch. Then slide the
heat-shrink tubing over the wire and out of the way before placing the terminal
on the end. Slide the wire into the correct size ring terminal until the
strands exit the ring side of the terminal by a hair. Crimp the ring end of the
sleeve first, then the wire side. Test the crimp with a hearty tug. Then slide
the heat shrink tubing over the connector so that it just covers the protruding
wires on the ring end of the sleeve and overlaps the insulation on the wire
end. Avoid sliding the tubing over the ring area, as this will interfere with
the screw contact. Next, heat the tubing just as you did with the butt splice.
If any wire strands are visible at the ring end of the sleeve, seal them with
an electrical sealant.
The Finishing Touch. Supporting the wire before and after the connector will reduce
tension on the splice itself. Either bundle the spliced wire to other wires
with ties or use wire clamps to hold the wire to fixed parts of the boat. If
two adjacent butt splices must be made, stagger the splices by a couple of
inches. Should the wires pull apart, they won't short against each other. In
any location where moisture might wick down the wire and into the splice you
should form a drip loop. Simply make a bend in the wire that will cause water
to drip off of the wire before reaching the splice. After the new wire is run,
it should be labeled on both ends.
So now if you add
voltage to that rotted copper wire... and remember, a
reaction will also occur without the presence of chlorine; but chlorine (that
chemical that also eats stainless), a small atom and an excellent oxidizer,
greatly accelerates the corrosion process.
Also, a site I like, providing a real
good overview, with specifics, on the total electrical system.
http://www.islandnet.com/~robb/marine.html
So, that shiny brown copper wire maybe a good price but do you
really want to reach down into the bilge to redo that float switch at the worse
time, or wonder why that navigation lights don't work, working into the harbor
at night, pull the anchor up by hand, and the start or kill switch on the
engine won't work, etc.
Hanging by a
Thread
I survey to ABYC voluntary "specifications" and at times had to write in
my reports that the ball valves on a vessels thru-hull fittings do not comply
with those specifications, especially those below the waterline. Some times
that's 20-30 ball valves! So what's the difference? First, here's what they
look like.
Ball Valves Sea Cocks
That "base" or "plate" at the bottom of the sea cocks is the first
difference. Also, most of the ball valves I have seen are "taper" threaded.
Tapered threads were designed and invented to help a joint not to leak. That's
great but most thru-hull fittings are straight threads, like these.
 
So, you screw a straight thread to a tapered ball valve, it goes in a few
turns, then won't go any more, with some sealer it probably will not leak. You
notice an inch or two, or maybe four or five between the ball valve and the
hull? That's what I mean by "Hanging by a Thread". A 1 ½"
thru-hull fitting maybe have 3/16" wall thickness before it's threaded, and I
don't know how deep those cuts are in the threading process. You could end up
with a nice 1 ½" hole below the waterline with only a 1/8" of wall thickness
between you and lots of water. You really don't want to step on that fitting,
or drop anything heavy on it, or yank too hard if the handle is frozen! And if
it does fail below the ball valve, just what was the ball valve for? You say
you have a bilge pump? That's great, here are some approximate water
flow rates for different size holes, just 2 feet below the waterline:
(Head intake?) 1" - 950 gallons per hour
(Head discharge?) 1 1/2" - 2080 gallons
per hour
(Small engine intake?) 2" - 6,666 gallons per
hour
(Large engine intake?) 4" - 26,670 gallons per
hour
The idea behind a sea cock is that with a small block under that straight
threaded sea cock base or plate shown; you can tighten down all the way to the
hull. You end up with a thru-hull fitting "sandwiched" between hull, inside
block, and then the bronze base of the sea cock flush to the hull on the
inside. You can calculate the amount of thickness and mass that's added. Now
that 1 ½" hole, that lets water in, is more than likely, if
ever going to break, will be above the sea cock and you can turn that
water off. Last thing use a good sealer, NOT ADHESIVE, on that thru-hull
fitting! 3M, 5200 is mostly an adhesive, real trouble to get a thru-hull
off the hull or to back it out some to reseal, try a polysulfide like 3M 101. It's not difficult to work with but more time sensitive. You squeeze some on the fitting threads and both sides of the block, install the fitting, attach the large nut on the inside of the hull, tighten the nut down to 80%, then come back 4 or 5 days later and tighten down the rest of the way. Some boatyards don't like this stuff because of that, having to screw with a part twice. What happens with polysulfide is that it "cures" in those few days, like rubber, and becomes a watertight gasket. Same stuff that is between the boards on a teak deck, and lasts for decades.
Contact me
at:
Phone: 808-375-8260
Email: Bob@BoatSurveyHawaii.com
Robert J. "Bob" Dupuis
Marine Surveyor/Consultant
|
