Shown is the dogbone reef. This is a great improvement over the simple grommet as you can engage the reef hook without bending and twisting the`sail (and risking a tear ).

Question: I sail a Cape Dory 27 single handed and plan on taking her offshore. Are there any advantages to adding a third reef and if so would it require additional hardware?

Answer: Three reefs in a mainsail is quite common, especially for long distance offshore sailing. It is an advantage to have a third reef, as taking this reef is far simpler than setting a storm trysail (which many would also have as the next step). You would use the third reef when cruising whenever the wind conditions warranted shortening sail to this degree.