Aluminum Wash with mild soap and water (ex. Ivory liquid) after each use and every 2-3 weeks that the boat is left outside in a marine environment. Do not use harsh or abrasive cleaning products as they can remove the anodized coating which will cause pitting. Pay special attention to the upper tubes of a hardtop or t-top. These areas do not benefit from rainwater which will naturally help rinse off salt residue.
Stainless Steel See info above. Can also polish with Flitz metal polish.
After cleaning, coat all metal parts and hardware with a non-abrasive metal protector such as Boeshield's T9 or Aluma Gard. These products displace moisture and leave a waxy film that will protect the surface from salt and other contaminants such as acid rain.
NOTE: Do not use abrasive cleaning polishes or products such as pads, steel wool, or steel brushes on anodized aluminum parts as they will damage the finish.