How much does a stay sail really add?

[Ian McColgin]

On most boats the staysail will give a serious boost unless it's light air and a 200% or more genny. So, why not test your speed with your actual sails? So much better than hypothetical answers.

G'luck

[Brion Toss]

Hello,
My friend Hasse, the great sailmaker, says, "If you set a forestays'l, you'll gain half a knot. And if you strike it, you'll ... gain half a knot." So usually the sail isn't worth it in combination with a well-set Genoa, but it is certainly great to reef down to.
As for easy handling, a Genoa should be handy with the forestay detached. If than's not enough, the best boomed stays hinge on a pedestal a calculated distance aft of the stay. And the safest ones have two sheets.
Fair leads,
Brion Toss