Ok, so what you're saying is that i can do this but need to take into account stresses. The boat i wish to enlarge is 780 mm in length, the beam is 220 mm across, the mast is 1200 mm in height and the keel is 180 from bottom of hull to the bottom of the lead bulb. Just say i wanted to lengthen it to 1200 mm, what would all the other diamentions need to be? Approximately?