Portsmouth rating

I began the quest of classifying my highly modified 18 magnum to enter a race with the right portsmouth number. As I gathered info I was able to gain the square area of the 18 and 18SX jib and mainsail independently. I have no idea how these numbers are calculated but since they came from Hobie directly I assume them to be correct. H18 jib 62.1 ft, main 140.7. The H18SX jib 64.4 and the main 155.3. I stupidly thought the Tiger main was close to the same size, it's 183. The Tiger jib is 44. So based on that math my total sail area will be 470 ft, 18ft more than a Tiger. So in portsmouth numbers the boat is rated faster than a Tiger, I doubt that very seriously as I have ridden a Tiger and believe it to be much faster than my boat could ever be. Its even rated faster than the Fox which I know will blow its doors, as I used to own one.

Well I was wrong about the number but think I have it right now. H18 and H18 Mag have a DPN of 71.4 and I have a non-class legal main of greater size .980 penalty, a taller mast than standard .995 penalty and a spinnaker .960 for a modified DPN of 68.5. The Tiger and Fox have a much lower number. I originally calculated too many penalties, read the rules closer, got some input and came to this. I'm sticking with it.