As other's have said, you use the vang to control leech tension on a mono. I had an I-14 for a while that was built in the early/mid '90s - full carbon hull and spars and huge assymetrical spin. Very cool boats, but a lot different from cats. If you have minimal or no dinghy sailing experience, get ready for a steep learning curve and be prepared to get wet a lot. I enjoyed sailing the boat the few times I had it out, but the problem was always finding someone with enough experience to crew on it. The boats are a blast though when you get them dialed in.

You may want to check out the forum at international14.org.

sm