TL;DR: What is the best practical protection against deterioration of a steel hull from rust or electrolysis? - I already have Zinc anodes
Apologies if this is in the incorrect forum. I am not a chemist, so my presumption that this is a chemical engineering question may be incorrect.
I own a steel inland waterways vessel (Narrowboat) which is my first live-aboard project.
A common maintenance requirement is "Blacking" beneath the waterline with Bitumen to provide a protective layer against the water to prevent rust. This is meant to be performed every 3 years.
I also already have Zinc anodes.
I have been attempting to research an answer to the question: "What is the best practical protection against deterioration of the hull by rust or electrolysis?"
I have attempted to remind myself of my pre-college Chemistry education by researching on Wikipedia the subjects of chemical bonding and electrolysis, and have lead myself to more questions than answers.
I am aware that Zinc galvanisation is a popular solution to protecting Iron - https://www.youtube.com/watch?v=iRrdAM-3nq0
- though this appears to be at odds with Narrowboat forum recommendations - https://www.canalworld.net/forums/index.php?/topic/81076-red-oxide-paint-vs-hull-blacking/&tab=comments#comment-1710101
So far as I see it, there are three options for protecting a metal object from deterioration:
1) Prevent rusting from occuring by applying a coating of an impervious wear resistant compound, such as Red Oxide
2) Prevent rusting from occuring by coating the steel with a conversion compound which doesn't result in rusting and prevents future rusting reactions.
3) Prevent electrolysis by applying a layer which either acts sacrificially or, ideally, neutralises electrolysis.
The questions I have are:
1 - What is the best wear resistant compound for steel, and what's the reason for that?
2 - What would be the ideal rust-resistant steel compound, which chemicals would be best to achieve that conversion, and again what's the reason for those chemicals achieving that result?
3 - Which chemical is best for preventing electrolysis, how thick of a layer would be necessary, what would be a suitable application compound - e.g. oil-based paint, epoxy or another - and how did you reach that conclusion?