Can a control line be attached to a sheave?

Thread starter #1
My question in the subject line is clear. For the purpose of completeness, all tangentially related rules and interpretations are given at the end of this post.

Rule 3(b)v notes the non-standard components a block may have (in addition to its cheeks, head, sheave, etc.) Implicitly, it relates to exactly where a control line can be attached to a block.

Note that Rule 3(c)i about the mainsheet is the only rule where we have a regulation about exactly where to attach a control line to one of the blocks in that control line system. It says: "The mainsheet shall ... be attached to the BECKET of the aft boom block." No such specific requirements exist for any other blocks on the Laser.

The rule about the Vang [Rule 3(d)] contains no references to where the (maximum of two) vang control lines are to be attached.

Rules 3(e)ii and 3(f)ii about the cunningham and the outhaul (respectively) are both plagued with the a wording problem: they both refer to and impose conditions on where "THE control line" is to be attached, in systems composed of multiple control lines. It is obvious that these rules apply to ANY ONE of the control lines in the system, and not to all of them.

Beyond that, these two rules do not specify where on a block a contol line can be attached, either.

Some historical precedents demonstrating that a control line CAN be attached to the sheave of a block exist. For example, in the new 15:1 vang systems, many hot shot racers reduce the power ratio to 12:1 or 10:1 by attaching a line around the sheave of a vang lower assembly block. (See "drLaser" website for descriptions.)

By the same token, suppose that I have an outhaul primary puchase line ending with a (single sheave) floating block. I should be able to legally tie a second outhaul control line just around the sheave of that block (REGARDLESS OF WHETHER THIS MAKES ANY SENSE OR NOT).

In fact, by virtue of Interpretation 2, to "attach" that second control line to the block, I should be able to pass the line around the sheave, and then through a BALL STOPPER, and just finish it with a stopper knot.

I would appreciate it if you could let me know if you see anything in the rules preventing this.

Shevy Gunter
Member, ILCA-NA

PS. Again, this is related to the outhaul clam cleat "remote uncleating" system.



3(c)i. The mainsheet shall be a single line, and be attached to the becket of the aft boom block, and then passed through the traveller block, the aft boom block, boom eye strap, forward boom block and the mainsheet block. After the mainsheet block it shall be knotted. The mainsheet shall not be controlled aft of the forward boom block except to facilitate a tack or gybe.

3(e)ii. The cunningham control line shall be securely tied to any of the mast, gooseneck, mast tang, the swivel, the shackle that may be used to attach the vang cleat block or the swivel to the mast tang, or the cunningham attachment point on a “Builder Supplied” vang cleating fitting, and shall pass at least once through the sail tack cringle before passing only once through the deck fairlead and the clam cleat.

3(f)ii. The outhaul control line shall be tied to either the end of the boom, the outhaul fairlead, the sail, or a quick release system, and shall pass at least once through the boom outhaul fairlead.

Interpretation 2: Where the rules allow for an optional block or shockcord to be attached to a fitting, line, mast, boom or the sail, it may be attached with either a shackle, line, shackle and line, clips, BALLS or hooks.


3(b)v. “Optional” blocks shall only have single or double sheaves, and may include a becket, a swivel and/or a shackle.