It's probably not necessary if they are not leaking, but everyone does seem to seal them. Note that there are foam plugs inside the pylons that will keep water out (unless they're rotted). There are vent tubes in the foreward pylon plugs. These tubes and the drain holes in the transon are all the ventilation you've got, unless deck ports are installed. That's why it's recommended that the boat be stored with the hull plugs out.