Actually, it's pretty easy to make your own conclusion here. You can experiment with height by using a short length of rope between tack and stem that you can adjust. Then go sailing and watch the speedo.
When you determine what length works best.... go over to West Marine and tell them you want to build a wire pendant. They have a little work area in the hardware department with tools and parts to do the job yourself.... they will probably show you how just the same. Essentially it's a wire with a thimble/eye on each end. Your choice on connectors.