No, roasts and turkeys do not need to be basted. During roasting, the convection fan will quickly sear the meat, locking in all the valuable juices. However, if you are using a marinade that is high in sugar, don’t baste with the marinade until the last hour of the cooking process. This will allow the roast to get a beautiful sear without the sugary marinade burning onto it. Convection air will sear faster, even when it is a sugary marinade.