Ontario mirror dinghy association. the ontario mirror dinghy association (omda) is an organization of people who have one main thing in common: they belong to a. Boat plans for power, sail and small boats. free boat plans. kits and supplies plus the best boat building technical support.. How to build a small sail boat. these plans are for a small sail boat called the biloxi dinghy. former builders claim it’s a great design.s. from the plans:.