Sainsbury's make an excellent prop bag it's called a bag for life and it's the strong orange carrier bag they sell at the checkout. 10 pence to you sir.
If however you have to pay more then go to Steel developments at the boat show and buy some prop sox. Nifty bits of kit.
Flew sails in Porchester will make you a console cover and I think there is a company called Custom Covers in Southampton.
Here it comes again, I don't stand a chance
Soul possession, Got me in a trance
Pullin' me back to you - Deja Voodoo