I'm a newbie at sailing and I've got an older day sailor, 16.5 feet long, its very similar to a Newport 16. It doesn't have any identification markers on it so I don't know who manufactured the boat. The previous owner told me it was over powered and the mast should probably be replaced with something smaller. I think I can shorten the current mast instead of buying a new/use one. So I'm wondering if there is general rule(s) of thumb(s) for mast lengths.