I need to respray the complete underside of my wave board - any recommendations? Something commercially available in a can would be great. I think normal car paint will probably chip off.

Thanks

Z

car paint

Yeah car paint... Go to a car painter that can make up cans of colour matched paint. Don't buy generic spray paint from your hardware store its crap.

The board repair guys I know just take the boards they are fixing down, get it colour matched and a can made up. About $25-$30bucks I think. Totally worth it.
The paint suppliers can also give good advice on preping your board for painting so you get a sick job.

Just to add...look at using a hi-build polyester base-coat, it helps with filling pinholes, and is easily worked whilst sanding back for the topcoat, advantage and disadvantage - it adds about .5mm thckness, which is good for protection, but not ideal if you're worried about the miniscule weight it adds, followed by a polyurethane, although a single-pack might do it too.
Panel-beater shop, or 2-pack spraying factory (cabinetmakers/joinery) should be able to help you out.