My boat is a 79' 18ft Baja with 403 and Berkley JE. This is my first boat and my question is concerning the Barr marine logs and risers. The exhaust exits the transom very low, well bellow the water line, and even though I have flappers I'm concerned with water entering the logs. With the boat fully loaded, the waterline is almost at the top of the riser. Do you guys think an internal flapper like the ones Rex Marine offers would be tight enough to fix my problem. Any input would be greatly appreciated.