>> I would like to find out what the exact definition of a spinnaker is, as well as a jib, from ISAF`s point of view.

Defination spinnaker/gennaker :

All trangular sails having a midgirth that is 75 % of the foot of the sail are spinnakers/gennakers

Don't need to give the definition of the mainssail here.

Than what we are left with are jibs, so the defination of teh jib can be written down as :

All triangular sails NOT having a midgirth that is 75 % of the foot of the sail are jibs.


All "trouble" can be traced back to these definitions.


>>If it`s due to the fact that it`s roller-furled,

No, has nothing to do with it. the only descriminating difference is the midgirth measurement.

>> If it`s because it`s flatter than an assymetric I would be surprised - define "fullness" -

No agian, only midgirth. You may cut a gennaker or spi as full or flat as you want to.


>>My question is, at what point does an assymetric spinnaker become a hooter, is it :
a) the fact that it furls

(wouter) No

b) the concave leech

(wouter) You just loose sail area by doing that.

c) the fact that it is flatter (if so, at what "fullness/flatness" does it change definitions ? How do you control that ?

(wouter) No again.

d) the fact that it can be used to sail higher than a beam reach

(Wouter) No


There is only one aspect that determine wether a headsail is a spinnaker or a hooter and that is the midgirth measurement.

When this is less than 75 % of the foot => hooter
When this is more than 75 % of the foot => asym spi or gennaker.


>> The Hooter type sail probably suits this role better than an assymetric.

Depends on what course you are sailing at the moment.

Wouter