Folks, he is sailing in a Rhodes 19!!! No V-berth or cabin.
MITBeta, The reality is that the boat you are sailing in is not especially conducive for longer jaunts with small kids. My best advice to you is limit those trips to about an hour or so for now. As the kids grow or their tolerance improves, you can begin to stretch it out.
Now you understand why so many of us spend what we do to have our own boat with a comfy cabin that can be set-up with all the entrapments of family life. It's either that, or much shorter sails in daysailers.