I replied to that thread as well. You can use the search function.

Just a few quick points. We routinely charter with our young kids. Age 3 and 5 now (started regularly at 1 and 3). We always sail on a monohull which I find much easier to watch them aboard. It has one exit point which is the companionway. We’ve been on catamarans with our friends and there is too much room to safely watch them and sail.

Basic safety measures. ALWAYS know where they are and watch them closely. When underway, they ALWAYS have life jackets on and are always clipped into jack lines with a tether. Once at anchor they are free to play without life jackets but we ALWAYS watch them.

Our kids are young though. I would think an 8 and 11 year old should be pretty good with listening, wearing life jackets at all times, etc. Regardless of age, it’s always good to prevent a man overboard.

Also, when just my wife, me and kids, my wife and I always wear inflatable life jacks underway too.

Have fun.