If it's hypalon, I had great results with Fairy power spray and magic sponges. On their own, each of them cleaned it OK, but together it came up spotless. Don't use the power spray on PVC or other materials though as it makes the tubes sticky, and even on hypalon i'd try a small bit first, and rinse the tubes off straight away.
It's also important to treat the tubes with a conditioner / sealer afterwards, as the newly cleaned tubes pick up more dirt.
I was given some by the Pennel rep at a boat show and it is probably the best tube cleaner I have used, especially combined with the magic sponge. Not certain whether it will improve the fading though, and not sure if anyone in the UK stocks it?
The poor old avon was dragged out to daylight today for a bit of a scrub,boy did it need it,
Last year i discovered a cleaning product thats needs very little elbow grease to get great results,
So all you do is wet the tubes,spray it on about 18" at a time,leave for 1 minute and wash off,took approx. 1 hour to clean the 3.1 rib from a very grubby ditch colour to near perfect white again,
and here is the product,no affiliation here except a very satisfied customer,costs about €11.00
Nice post but I didn't have the same success on a PVC air deck when I tried this stuff. I think the Avon is Hypalon though and this may be part of the reason. The really bad stuff in this case was exhaust black and I used 'Jizer' (engine degreaser) to get past that.
Power spray / Whizz stain removers works well with white eraser sponges as they do for white cockpit seating. The 'sticky' feel mentioned by 'Nick_H' above is normal but this just wipes off with a damp cloth.
The sealer sounds a good idea but any auto 'minute wax' will provide a coating to prevent dirt sticking again. /forums/images/graemlins/wink.gif
Just one point. I've seen rib tenders lifted out that have been floating for a season without antifoul and these don't clean up to well! /forums/images/graemlins/frown.gif