For a recently finished pulling boat I used open type oar locks and for starters used commercially bought oars. I found that relative to the size of the locks these oars are "pretty thin" and there is a lot of play between the two. Wanting to build my own oars I would like to know from folks out there with rowing experience if there is an optimum diameter for the oars for best performance in open horn type locks: should the oar fit tightly in the locks, should it be relatively tight or does it really matter??