Does ceramic coating replace bottom paint?

No. Ceramic coating protects above-waterline gelcoat from UV and staining. Bottom paint contains biocides that prevent marine growth below the waterline — they serve completely different functions.

Can I put ceramic coating below the waterline instead of bottom paint?

No — ceramic coating has no antifouling properties and won't prevent barnacles or algae from attaching to the hull.

How often does bottom paint need to be reapplied?

Most bottom paint needs reapplication every 1-3 years depending on the paint type, water conditions, and boat usage.

Bottom Paint vs. Ceramic Coating: What Protects What on a Boat

Bottom paint and ceramic coating protect completely different parts of a boat, for completely different reasons. Here's the distinction owners often get wrong.