Rover
I've had great luck with the MAAS paste; especially using an applicator ball in a drill. The paste has jewelers rouge, will polish off corrosion and scale.
Follow up with a good liquid wax - like 3M; the pipes will look like new.
Works on alum, stainless and plastic (although I wouldn't use on the clear plastic windows)
You can get the MAAS here - the 1.1 pound can (polish cream) will last for years
http://www.maasinc.com/products.asp
Good luck with the new boat