Far as I can tell, someone wrote:
I was told it would need to be sanded first. Is this right?

I don't know boat finishes from any other, but just consider that the
paint you put on ANY surface will adhere no better than whatever is
already there. Is there wax on the boat now? Dirt? Embedded sand? Salt?
Plain old crap from the water?

You know the old adage. If it's worth doing, it's worth doing right.
What if a year from now the new finish starts to bubble or peal?

At the very least, clean the living daylights out of the surface you are
going to paint, and follow the instructions on the paint can regarding
priming or re-coating.