Hi Roberto,
I have aimed to rig mine as per the rigging manual's suggestion of 100mm and on checking it is 120mm, so pretty close.
The Class Rules say that;
C.9.3 (a) ....The traveller rope shall not extend more than 250mm above the deck at its highest part.
That rule is to stop slack travellers exerting too large an upwards force on the deck fittings.
