Rigging a mylar jib

Rule F.4.5 states: "When a mylar jib is used, a jib furler and swivel are not fitted, and a jib halyard and associated fittings, as supplied by the builder, are required. Any replacements of the supplied equipment are subject to all applicable rules, including C.2.4 and F.4.1.”

The Designer's list of the equipment "supplied by the builder", together with the designer's instructions for rigging, are as follows:

Note: A forestay length of 4077mm + 25mm (RM124 U-bolt) + 17mm RF616 Dee shackle at tack) + 21mm (RM635 ¼” bow shackle at hounds) gives a total length of 4140mm, the mid-point measurement specified in rule F.1.3.

Instructions:
Screw cleat to aft face of mast, either side, in lowest convenient position.
Pass purchase rope through hollow rivet of hooked block and deadend with knot.
Pass other end through slot under cleat, then around sheave of hooked block, then through cleat to give a 3:1 purchase.
Shackle RF20100 swivel top block into upper thimble of forestay, or around the ¼” bow shackle. Both equally good, but stow differently.
Pass halyard end through parel bead, deadend with knot.
Attach halyard to jib by doubling end of halyard, pass loop through cringle in head of jib, capture loop by passing parel bead through loop, draw tight.
Adjust halyard length with knot in parel bead. Cut off surplus.
Tie halyard fall into loop in halyard.

For those owners who wish to pull the head of the lowered jib down positively to the bow U-bolt from the cockpit, I approve:

Tie one end of about 8m of 1mm or 1.5mm line (suggest VB cord) to the jib head cringle.
Run the line down the forestay inside the jib hanks, back through the bow U-bolt, back along the foredeck, and secure neatly by tying it to a swing strap saddle,

No extra cleat is needed nor approved.

Frank Bethwaite
Designer.
21st February 2006

Some additional notes:

1. North American boats have a shorter Ubolt at the bow, so the forestay needs to be longer (4085 mm).

2. The halyard may be attached to the jib with a shackle, instead of using the parel bead.

3. The halyard may be lead through a sailmakers thimble at the top of the forestay, or through a small block. The block can be attached to the forestay with a shackle, or with a swage as shown here:

4. The purchase rope may be led through the slot under the CL704 (as in the instructions above), or through a cheek block (e.g. RF 661) attached to the aft face of the mast, or through the roller on a CLM 236 ClamCleat or similar. A purchase of either 3:1 or 4:1 is permitted.

ClamCleat CL 704 with slot

ClamCleat CL 236 with roller

5. A vernier stay adjuster (Holt Allen 4272 or similar) may be used at the hounds. With the additional shackle required to attach the vernier to the bow shackle at the hounds (see picture below), the forestay length is 4030 mm.

Posted 2006/03/03

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