With some creative thinking and rigging, a safety line could be rigged to not only keep you attached to the boat, but also to deploy a small anchor or sea anchor. Around here (FL) most of the sailing we do is done in quite shallow water. 50' of small diameter line on a jet ski anchor should stop of drastically slow your boat if you get seperated. For deep water a sea anchor could probably slow the boat enough to allow you to catch back up to it, and keep the pressure off the teather.