Blackfly is an open sailboat that is light enough to portage and cartop, and capable of carrying as much cargo as an ordinary tandem canoe. The result is a burdensome but lightly built craft, suitable for sheltered waters in fair weather. A good way to go is the use of a 75 sq. ft. standing lug sail. Here are plans to make one yourself.
The plans are available in many formats so there should be one that fits your needs.