There is no good reason for using high carbon steel in a yacht hull.

It's harder to weld.

The weld heat affected zone has different characteristics to the parent
material, usually worse, nearly always different corrosion
susceptibility.

High carbon steel has somewhat greater tensile strength, but so what.
Steel yacht hulls are massively overstrength anyway, the plate
thickness is set by the need for min thickness for corrosion allowance
over the life of the hull.

High carbon steels with heat treatment become brittle and can fail from
shock loads. Not that anyone in their right mind would do this WRT
boats.

High carbon steels do *not* roll and hold their shape nicely, WRT low
carbon steels, because they WORK HARDEN and if not annealed, become
brittle and develop stress cracks and fail.

High carbon steel does *not* slow rust appreciably. Some steel alloys
have greater corrosion resistance but this is due to the alloying
elements, not the carbon. In fact, very *low* carbon steel resists
corrosion better than high carbon steel.

Feel free to argue about it all you like. I'll just quote more bits
from 'The Procedure Handbook of Arc Welding' by the Lincoln Electric
Company.

You might own a steel boat, Joe, but so do I. Just that mine's bigger
than yours :-)

PDW

In article .com, Joe
wrote:

Stronger, harder, stronger.. Steel with sufficient carbon compositions
can be heat-treated, allowing
parts to be fabricated in an easily-formable soft state then made
harder for structural applications.
High Carbon steel rolls and holds it's shape nicely, and I suppose high
carbon slows rust too!
I've never seen a carbon anything rust.

Joe