We had the scrub forever, flaking no matter how much your sanded and scrubbed problem as well. Finally bit the bullet, turned on a bilge pump and started pressure washing... Three passes later it was finally good enough that we felt we could paint on top.
We used kitchen bathroom paint over a primer in a semi gloss for all the same reasons you express. Looks really nice, but I can't speak to the longevity of the product.
Pressure washing sounds lovely, I figured it wouldn't do much though?
The paint isn't really flaky anymore, unless you go after it with a sharp scraper, below the layer the stupid owners put on there is some discoloration that looks like dirt or mold, then the previous paint, most of which is fairly well bonded to the hull. (I find I have to sharpen ever 4-5 min to keep it working efficiently).
The sander is slow, I tried a stainless cup brush wheel on my angle grinder, but it was too dusty, and got in my eyes, I went back to the random orbital sander.
How much sanding/scraping is enough? I just don't want paint that seems reasonably well stuck now peeling later, and based on the fact that the coat below looked dirty I'm not sure what to do.
I might be nuts, but I love pressure washing inside my boat.
Bit worried about it running into the main cabin though.
Did you use a mold resistant primer? It turns out my paint is a acrylic bathroom/kitchen scrubable paint, I was mistake. My primer does not indicate mold resistance, and I don't want to cause the same kinds of issues the last idiots did, this has NOT been a fun project.
EDIT: Here's my top coat.
And here's my primer