Peter,
I believe the mileage number. Not because of the navman F3100, which is on it's second sender and due to be trashed because they won't replace the non working display, but because I travel 60 miles fishing and put in 20 gallons somtimes 15 gallons for the last 3 years. I believe my boat is a lighter 23SF than most I've seen. I removed the livewell in the back relpaced the transom with Coosa 26, have a 100 gallon tank, and I think the foam is dry. Sitting at the dock the corner of the transom is only in the water 1/2" and the splash well drains are 3" above the water. Sitting next to Scott's boat mine sits 3" higher. It also feels lighter than scott's when riding in it, but that might be because he drives fast and me and my herniated disc's like slow rides. I also have seen the hull thickness cores that other people cut out of the hull and mine is not that thick, maybe 5/16" thick at most. So I have a light weight 23SF but I love it with the 200 Yami. I just need more fishing time.
http://i15.photobucket.com/albums/a3...2seacrafts.jpg
http://i15.photobucket.com/albums/a3...y/transom2.jpg