Chief Measurer has added CMR 90:
The bitter end of a 2:1 jib sheet may be dead ended at the jib track slide or the center of a
“carbo air” block or similar. The use of a block with a becket is not permitted for the jib sheets.
Jib sheet blocks are not to have a sheave in excess of 76 mm (3“+/-) See CMR 6, 48, 78.
Background: There has been recent questioning tying the bitter end of the 2:1 jib sheet to the
center of a “carbo air” block or similar. This was reviewed years ago by Bob Neff, the Chief
Measurer at that time and Harry Carpenter, representing the builder. They determined then,
that the difference in performance was negligible and outweighed by the convenience of tying
the sheet off through the block. The Measurement Committee recently reviewed this and
concurred with the original findings.