how do I find the manufacturer of my Merit 25 sailboat?

Answer 1

Well, there seem to be quite a few manufacturers - and some might not exist any more.

Have you got any kind of papers to the boat? Actually there should be a badge at an easily accessible place with all the information - like manufacturer, serial number, construction year.

Perhaps ask someone where their badge is mounted in a sailboat (of any category), just as a hint for you.