Folks
The varnish on my hull has done well to last this long I reckon but I think I need a more durable solution. I was thinking epoxy, microballons and carbon mix. Any advise around on the subject - the thought of the dust raised by sanding that mix doesn't sound pleasant. In particular was wondering by way of application if a runny goo would be better than a thicker mix?
Many thanks
Pat

If you want something durable for your hull (to resist scratching) you need colliodal silica aka Cab-O-Sil aka 'NoSag'. It's an excellent additive for epoxy- you can add quite a bit to the mix without getting the 'dry' quality that you get with microballoons- and makes a very hard coating when cured. Naturally, it is also hard to sand.

Microballoons are useful for fairing and filling, but do not produce a very hard result. I wouldn't recommend them for your hull.

To add black colour to the silica, you can add some graphite. Cheaper, blacker, and harder is 'black iron oxide' which I learned about via Bjorn Thomasson's website. It can be found via pottery supply places (used in some glazes??) or online via sellers on 'the big auction site'. A kg will probably be a 'lifetime supply'.

Graphite and epoxy (without silica) is a good mixture for low-speed bearings (rudder stocks in sailboats) but is not hard enough to add much scratch resistance to your hull.