[Bernardo II]

Un artículo en ingles sobre el tema

CHECKSTAYS (BURDAS)
They're running backstays (backestays de labor)

Don't know why they're also called check stays, except that the can be used to "check" mast bend, outside of stopping the mast from pumping

They are behind the mast, like backstays. Typically only on a fractional rig.

They can have two purposes:

In light air, ease the backstay a bit (lets top of mast forward) and pull on a bit of checkstay (pulls center of mast aft) to straighten the mast (not invert it, just get it more nearly straight and take out some of the bend). This makes the main fuller and more powerful.

In heavy air and waves, with the backstay cranked fully on (to flatten / depower the main), the middle part of the mast might pump forward and back. If so, a little bit of checkstay tension (not enough to straighten the mast) can stabilise it and stop it pumping.

Not very common these days, AFAIK. Typically only necessary or useful on a very bendy mast.


"The traditional fractional rig, normally with in-line spreaders must use running backstays (runners) to stabilise the rig. Checkstays are mostly used on racing yachts to control the mast bend in the middle and lower parts of the mast.
The runners have the same function as the backstay on a masthead rig. Forestay sag will decrease and the mast will bend to flatten the main, when you tighten the runner. The permanent backstay on such a fractional rig is primarily an insurance against rig failure when gybing"