Malcolm,
Yes you can use stainless for a boat, but it should be a copper alloy
stainless, not a 300 series. This material does not have to be painted at
all, it will reject growth all by itself. There are disadvantages, like
cost, less fatigue resistance, the high cost of repair and weight penalty.
It is very hard to beat low carbon steel. As a test, suspend a sheet of bare
steel with nylon line from a float to a depth of 36" and leave it for 6
months. It'll be almost as shiny as when you put in it. If you really are
serious about this, try different alloys of magnetic steel and iron, then
observe the results. You will find that the different metals corrode quite
differently. To best observe this test, the metal should be placed to
transition between air and the water.
Steve
"malcolm" wrote in message
...

"Steve Lusardi" wrote in message
...
Dave,
Not to get too technical, stainless is an alloy of mild steel, Nickel
and
Chrome. The percentages of the alloy mix and small amounts of other
metals
enhance certain characteristics, like corrosion resistance,
machinability,
heat resistance. Generally speaking, the 300 series alloys are
non-magnetic
and corrosion proof, where those alloys in the 400 series are magnetic
and
only considered corrosion resistant. The mechanism that SS exhibits to
prevent corrosion is controlled corrosion of the exposed surface. In
fact,
its corrosion resistance depends on the availability of free oxygen. In
an
environment of depleted free oxygen, any surface damage will create
"crevice
corrosion", which is much faster and more damaging than would be
experienced
with normal mild steel. Even 316 SS, which exhibits the most resistance
to
corrosion, should never be used below the water line, especially where
there
is not good water flow, like bolting lead keels to the hull. Anything
that
can damage the surface of the part, whether it is mechanical like
rubbing
or
electric as in electrolysis, will rapidly kill the piece. Please keep in
mind that SS is non-homogenous and can be considered to be millions of
little batteries in an environment that could work as an
electrolyte.(salt
water)
Steve


can you build a sea going boat from stainless steel?
and what happens if it is painted with anti-fouling?