What is D12? Some kind of line?

I'm in the sub tropics, we can get really strong downdrafts when thunderstorms are in the area so I need to be able to reef in an instant.

I sailed a TheMightyHobie18 quite a lot and relied on the furling jib. It made me feel very secure. Usually I could just run away from anything really nasty but then there was the problem of the calm after the storm.

Also, I've been thinking about a cleat for the spin sheet, even when racing.