How to Install a Precision Sails Lazy Jack Bag System

The Lazy Cradle is possibly the easiest way to cover your mainsail and is perfect for short-handed crews. One simply lowers the halyard, settling the sail in the cover, and zips the top for complete coverage.

The Precision Sails Lazy Cradle Boom Cover is manufactured from solution dyed Acrylic Sunbrela brand fabric with polyester or nylon webbing so that, while it keeps your sail clean and protected, it is itself appealing and compliments your boat. This fabric is used specifically because it can offer protection against physical abrasion as well as the elements, especially UV damage. As well, its ability to breath prevents any threat of mildew.

Along with the Boom Cover, the Cradle comes complete with mast collar, lines and rings. The cover is stiffened at the top with battens(optional) that hold the cover open when raising or lowering the sail and provide a straight clean look when not in use. A YKK zippered flap closes the top as well as the forward end. The zipper sliders are fitted with lanyards and close bottom up for easy use.

Much like a sail, the sail cover of each boat is unique and should be tailored to the specific dimensions required by the vessel’s set up. At Precision Sail we provide an easy to use and comprehensive measurement form that will ensure your cover operates effectively so that you can get the most out of your sails.

How to Install Video Precision Sails Lazy

3 Grommet Bag Video Below


Rough out the layout of your Precision Sails Lazy Jack Bag on the lawn or floor to ensure good angles are achieved to support the bag well.  Use a 2X4 or a long line to simulate your mast and use the bag to simulate your boom.  The goal is to have the bag supported and the lines to guide the sail down into the bag.   Additionally, you can watch how Calico Skies installed their Precision Sails Lazy Jack Bag on their boat here.

Lazy Jack Bag and System Install Instructions:

There are many ways to arrange the lines, however my preference for a 4 grommet system is to make 4 sections of rope and use 3 rings per side. (See Diagram Below) For a 3 grommet bag use the same general layout with 3 lines and only 2 rings.

Install Battens

If you chose to order round fiberglass battens with your bag, attach the battens together with the sleeves and cut to length if needed (use hacksaw)

If you didn’t order battens, 1″ PVC piping works well. Cut to length and insert in the batten pockets on both sides of     the bag

Lines 1 & 2 – Rings 1 & 2

Line 1 & 2 should be approximately the same length.

Line 1 runs from grommet 1 to grommet 2 through ring one. (do not attach the ring to the line)

Line 2 runs from grommet 3 to 4 through ring two (do not attach the ring to the line)

To attach Line 1 and Line 2 to your bag. Run the line through the grommets and tie directly to the batten inside the        bag.  A bowline knot is a good choice.

Line 3 – Ring 3

Line 3 is tied to the ring on Line 1 runs through ring 3 and is tied to the ring on line 2.

Control Line (Line 4)

Line 4 (control line) is tied to ring 3 and runs vertically through the block on your mast and down to a cleat toward the   base of the mast.

Control Line Blocks – The control line will run from the highest ring (ring 3) up to a set of blocks on the mast and down to a cleat toward the base of the mast.

The blocks should be installed approximately 1/2-3/4 from goose neck to the top of the mast (the longer the boom the higher you should install). The exact location will depend on other lines, gear, spreaders on your mast. Find a location that is at least 1/2 the way up the mast to ensure there is a good angle to keep the lines high enough to catch the sail.

See Diagram Below: (Four Grommet Bag)

Lazy Bag Install

Lazy Bag Battens

Lazy Bag Jack Lines

Lazy Jack Lines

Pictures courtesy of Carl Kotheimer

Operating your Precision Sails Lazy Bag:

Once you bag is installed you are ready to go out and give it try.  You have two choices while sailing:

  1.  Leave the lazy jack lines and the bag up.
  2.  Release the lazy jack lines by releasing the support line from the cleat at the base of the mast.  Bring the lines close the mast and tie them to the mast out of the way of the mainsail (use a line or a bungee).  The bag will now also be lowered and can be attached to the boom (sail ties work well) and kept out of the way of any rigging or the sail.
  3. When you are ready to lower your mainsail, prepare the lines and the bag back their original position and lower the bag directly into the bag allowing it to flake naturally.  Once inside the bag close the zipper.

If you have any questions please reach out for help.


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