Without a doubt, the best way to “clean” stainless steel parts is to have them electropolished. Electropolishing is an electrochemical process that cleans the stainless and removes any surface iron particles, leaving a shiny and far more rust-resistant surface. The downsides of electropolishing are its high cost and the environmentally unfriendly waste products resulting from the process.
Another option is to manually polish and buff the stainless with cleaning compounds and either a rag or power buffer. This is definitely a far more environmentally friendly process, but very time-consuming and not quite as effective as electropolishing.
Fortunately, there is also a third way to clean stainless, at least those small parts that are not attached to the boat—citric acid. Citric acid powder is derived largely from citrus fruit and is very environmentally safe. Food-grade citrus acid powder is even used as an additive in snacks and pharmaceuticals, and then added to water and heated, becomes a safe-to-use “poor man’s electropolish” for stainless.
I personally use a hotplate to boil the water and an old stainless saucepan to hold the parts and citric acid solution. Depending on how badly the parts are rusted, I mix between 1½ to 3 cups of citric acid powder for each quart of water, then boil the parts for 20 to 60 minutes.
Be warned, the citric acid bath will not remove sealants or other non-metallic substances, so any silicone rubber or caulking compounds you want cleaned off must first be removed by hand. Once the parts have been “boiled” clean they then need a thorough cleaning with freshwater to remove any and all traces of the acid.
While not perfect, a citric acid bath does a very effective job of cleaning small stainless parts with minimal effort and at a very reasonable cost. Five pounds of citric acid costs less than $15 online.