Faster's advice is sound on this. Much better to get the lead for the tack line
forward of the headstay.
[Here I'm assuming that by gennaker you are referring to a sail that is akin to an asymmetric cruising spinnaker
. If you are actually referring to a gennaker with a taut line
or wire in the luff, or one that is on a furler
, then the advice below does not apply.]
Folks that are using a padeye on the foredeck (aft of the headstay), as an attachment point for a block through which they run their tack line
, are usually doing so because the padeye was there in the first place as an attachment point for a conventional spinnaker
pole downhaul. If you don't have the padeye, and don't plan to fly a conventional (symmetric) spinnaker
, you don't need the padeye.
Also, the piece of equipment that you refer to as a parrel is not usually necessary if you have a true asymmetric spinnaker
/gennaker. Sometimes it's helpful to have one, but they are more often used when someone is trying to fly a symmetric spinnaker
like an asym -- i.e. without a pole.