93 Thompson/yamaha sterndrive

Hi, I'm in need of guidance please! Second owner of now seven years, ran smooth all season with the exception of new plugs and a fuel pump. No oil leaks either. Launched it for last weekend, shortly after reaching 30mph it made a loud pop noise and oil was pouring out from bottom of engine :'( My kids are so sad! Can anyone tell me how I can fix it? Where to find parts (brand specific..hard to find)?? Getting a new boat is unfortunately NOT an option, so please don't offer that solution..lol. The boat was immaculate before this, inside and out. I think polishing it is one of my hobbies! Any help to it's repair would be greatly appreciated! Thank you in advance!!