Here is a local Ulu sailing about a mile offshore. The sailors use an oar as a rudder and there is no dagger board that I ever see. They sail quite well and the boats are hollowed out logs so they're unsinkable. If they get water ingress; which they often do the manual bilge pump activates, the occupante, and water is scooped out with often a half of coconut shell.

Amazing how far from safe harbor we see these craft.

Go Slow
Sail Far
Stay Long