It's scary the first time, but you're not going to sink.

I installed a new ballast system this year and didn't glue in my fittings so every once in while one of them pops off and floods everything. The first time I was terrified and my bilge wasn't working, water up to the carpet, but I did your same process, disconnected one of the ballast fittings and used it to suck all the water out.

Yesterday I knew one of them popped off again(I need to fix that, 4th or 5th time), I could see the bilge running constantly, I was more annoyed we'd have to stop and re-fill the ballast....