Aluminium boats can sometimes get salt oxidation marks on them. Different people will tell you different methods and techniques to cleaning an aluminium boat hull. Here are a few that we have heard of:
Toon brite is good for cleaning off water marks, but watch out because this product will kill your grass. Make sure you follow the instructions and wear gloves.
First wash with clean water and no soap with a hose and dry off totally before shining with a mix of one litre kerosene with half a cup of compressor oil (just empty a small amount of kerosene out of the container and mix with the oil and shake well). This will require several old cloths but produce a good shine. Just make sure you don't apply to top side to avoid incidents with slipping overboard!.
Use a strong wax car wash product the first time and then a normal car wash product for future shines.
Beware of some strong aluminium cleaning acid products as some can leave a blotchy look on your boat.
Try out Sharkhide or air co for a good clean. Sharkhide seals the aluminum the same way that paint does without actually having to paint it. Sharkhide is invisible. Wipe it on with a 100% cotton cloth.
Woody wax will keep your boat shiny. They have packs that come with wire wool and restorer.
After polishing, corn starch on a clean dry towel will take off any haze.