Stufft, the whole point of the trip is an adventure for slow boats which wouldn't normally join a fast cruise or venture such distances on their own. the legendary Gurnard travels at a relatively sedate pace exploring along the way, I usually cruise at 18kts but can be slower in poor weather. at that speed though the whole trip would only take about five hours return, so we will be taking our time to make sure it is worth the effort - like your GF I need a good reason for roughing it.
We do need to be aware that if the weather is like this weekend then the trip is likely to be rerouted (possibly to the pub!) and of course we will all recognise that the smallest boats are most like to suffer most in poor conditions.