First of all as this is my first post on this forum, hello to all of you and congratulations on a great informative forum. Have much admired some of the builds i have seen.
As to Andy's question, i am also involved in RC yacht racing including the iom and RM class.
Tried the exact same method as you for making my own bumpers using pollyfilla as a mould. After days waiting the result wasn't brilliant. Used bathroom sealant amd made sure all the air is out before putting it into the airing cupboard.
There are suppliers that sell bumpers, especailly if you built their own design.
What design is it?
I might be able to tell you the supplier of a compatible bumper.
Kbits does a bumper that is sandable to your desired shape, as long as it ends up 13mm thick according to the rules. You stick it onto the boat then carefully blend into the hull shape.
As to deck patches, the really only real option if don't want to see your boat go to the bottom is self adhesive dacron. It is available in many colours, well proven and used by us that sail in all conditions. The stuff you but in DIY stores will go brittle and tear easily. Just make sure the area is clean and grease free and you will have a covering that will last for years if not removed. It can also be removed and reapplied, useful for airing out the boat after a days sail.
Just google the following names and have a look at their catalogues,
Kbits
Sailsetc
PJsails
Nylet
There is also Housemartinsails and bgrcyachting, not sure if they sell the bits you require. But they do make goods sails and rigs.
Or to make it easier, click on this
http://www.leicestershireradioyachtclub.co.uk/links.html.
Its our clubs website and has the most popular suppliers (just click on their names).
Hope it is some use. Any more questions just ask away.
Craig.
( ps, are you going to race it ?)