"William Heritage" wrote...
Needing to add jib sheets to a 33 foot on deck 11'6 beam ketch.
http://www.gulftel.com/boomer/Leeway01.JPG
Is there a rule of thumb or formula as to what length they should be.

Long enough to reach from the winch (with a wrap or 2) to the jib clew with
the jib blowing fully forward.