--- In harryproa@yahoogroups.com.au, "bjarthur123" <bjarthur123@...> wrote:
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> i think both of you are neglecting the huge performance value of the slot between the jib and main. the accelerated flow from the jib onto the back of the main is a HUGE benefit. 1+1=3. it's like a third sail.
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> i'm not completely familiar with all the boats out there, but are their any open development classes with no restriction on sail area for which a una rig is preferred to a bermudan? my impression is no. i infer that the reason is because for a given righting moment the most efficient sail plan is a bermudan rig. i've read that A-cats only have unas b/c of a restriction on total area. am i wrong on this?
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If a class restricts the total sail area and consequently the preferred rig is a una, this would indicate that same sail area to same sail area, a una is better.
When class restrictions emphasis another variable such as mast height, a sloop may be better but this could be because the sail area is greater or the total luff length is greater.
There may be gains from the slot effect but there are also down sides, for example, more end loses. With a rigid sail the situation is different but with soft sails I am not sure that sloop is better for a given sail area. A boat to boat comparison would be interesting.