Join Date: Feb 2000
Location: Annapolis, Md
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You don''t quite have that right. Here''s how it works.
On a fractional rig, the runners are for adjusting headstay tension. The permanent backstay (the backstay that runs to the masthead) is to control mastbend. Checkstays are to prevent overbending and pumping. If you only had runners and a permanent backstay on a highly flexible rig, the compression of the two backstays would induce too much bend and so you could never get the forestay tight because no matter how tight that the you made the runners the more the mast would bend.
On a Masthead rig, the permanent backstay, controls the forestay tension. The babystay works like the permanant backstay on a fractional rigger and so induces bend. On a very flexible masthead rig the runners and checkstays limit the amount of bending that is induced by the babystay, and resists pumping. Working in combination the runners and check stay can control where mastbend occurs in much the same way as a the permanent backstay and checkstay does on a fractional rig.
On most bendy rigs that have checkstays, they are needed almost all of the time.