I plan to call my insurance agent about this, but would welcome other input:

My boat is registered as a pleasure boat, and my insurance does not cover commercial or "for hire" use. I don't have a captains license either.

What would be the status (risk) of offering a free ride on my boat, captained by me and serving free food/soft-beverages as prize in a charity auction?

I'm thinking I could benefit the charity by hundreds (maybe thousands) and perhaps meet some nice people in the process.... assuming no accidents and no lawsuits.