The most common reason for scratches on the stainless steel handrails on a boat is the use of a hose that has not been cleaned when washing or rinsing off.
The hose, that may have been on the property flooring or pontoon, will have picked up grit this grit together with the hose, scratches the stainless as it is pulled again and forth in excess of the handrail.
To prevent this… clean the hose off prior to use, then spot sufficient hose size on board for the clean. This way you will not be pulling the hose back again and forth in excess of the rails. In which the hose does meet up with the stainless, tie off with a cloth.
So, how do you take away the scratches?
Neglect commencing with metal polish, as it will only eliminate the very lightest of scratches. What you need is a variety of grades of further good wet & dry sandpaper and some h2o, with a couple of drops of cleaning soap in to act as a lube.
Dependent on the depth of the scratches (some could be just also deep) 600, 800, 1200 & 2500 would be a great variety. Stick to with https://cokhithanhtuyet.com/lan-can-inox-lan-can-sat/ and finer grades until a reflection is shaped.
Attempt with the best you have to start with and only use a coarser quality if that fails to ‘flat’ them.
Illustration: if you have started with 1200, then use 2500 and end off with polish or compound.
For further scratches, you might have started with 600, so then follow with 800, 1200 then 2500 and complete off with polish or a compound.Others