Rob,
When you say 25% graphite and 5% silica, do you mean as a percentage of the volume of epoxy (i.e., 100 cc epoxy, plus 25 cc graphite, and 5 cc of silica?

: I've used this and it works. It gets scratched too but the slipperyness and
: hardness combine to damage less.

: Graphite Coating for Protection
: If you are really rough on you boats you may consider a graphite coating for
: the hull bottom.
: Graphite powder and Colloidal silica mixed with resin makes a very hard,
: slippery surface that can protect the bottom of your boat from injury.
: Graphite powder mixed with epoxy resin produces a black opaque coating
: that does not need varnish. This is the same graphite powder you may be
: familiar with as a lock lubricant. This surface is also low friction.
: Objects hitting the surface tend to slide off causing less damage.
: This coating is applied below the waterline on the boat bottom and can be
: re-coated as needed. Mask off the area and apply several thin coats.
: Per batch of resin add 25% graphite and 5% silica. Graphite powder (#423) and
: Colloidal silica (#406) is available from
: West Systems.

: All the best,
: Rob