I have personally winessed a 15 foot breaker off the stern and it will fill the
dinghy and JUST rip the dink off the davits (if you are lucky). I think there is a whole thread on this, so I will not regurgitate it all (I am also not the authority on where you stick your
dinghy!!! ew, that came out wrong), but unless you know your weather window for certain... put it on deck in my opinion.
If you are making a long passage offshore, you cannot guess you weather window for sure so better safe than sorry. Again, you do what you feel is right. As far as the cover over the dink, from what I have seen first hand, it would rip the cover off or fill it up. It would have to be a solid cover made of Kevlar to keep out a 15 foot breaker. Nah. I actually tow mine or lash it on the deck (unless I know my weather then I will run it up the davits).
Your choice though. You are the captain.
- CD