Mainsail handling system
The Lazy Jacks sail system is a method of containing the main sail when its lowered or during reefing. The Lazy Jack lines are installed either side of the main attached high up in the mast and down to the boom. Since the jacks are either side of the sail it can be dropped without falling on the deck.
The Lazy Jacks lines capture the mainsail as it drops. Lazy Jacks will not flake the sail neatly as the Dutchman system does but it will hold the sail on the boom.
The picture shows Roxy finishing the Vendee Globe race and you can see the lazy jacks attached to a white cover along the length of the boom. These Guys & Girls choose Lazy jack systems over Dutchman due to the extreme conditions they sail in.
Mainsail handling system
Lazy Jacks or Dutchman system
Lazy Jacks along with a Dutchman system helps sailors control the Main.
The difference between Lazy Jacks and the Dutchman system is the lines of a Lazy Jack system are positioned either side of the mainsail, while the Dutchman line goes through the sail.
The Lazy Jacks lines capture or cradle the mainsail as it drops. Lazy Jacks will work with a mainsail with a bolt rope, while the Dutchman system needs slides.
Lazy Jacks will not flake the sail neatly as the Dutchman system does but it will hold the sail on the boom.
The Lazy Jack system is much cheaper than a Dutchman system and no modification of the sail is required (although full battens work better),
The lazy jacks are attached to the mast with pop rivets or screws and the same at the bottom end . This process is relatively cheap and fast although you will need to go aloft.
With a Dutchman system when you are reefing or dropping the mainsail in heavy wind conditions the dutchman filament lines drag on the discs and that may prevent the sail dropping easily. This is why the Vendee round the world racers use Lazy jacks.
Lazy jacks attached to Mainsail cover
If you combine the Lazy Jack system with a mainsail luff track and slide system, the front of the sail may flake itself somewhat, and then you can tidy up later.
In the case of the vendee Globe boats the lazy jacks are attached not directly to the boom but to canvas which is in turn attached to the boom. This picture of PRB, shows how the canvas captures the huge mainsail on these boats.
A variation of this is the stack pack, initially developed by Doyle Sails (see below).
lazy jacks design
The Harken lazy jack Diagram shows the main components of a lazy jack system.
This is the simplest system with just one top leg and one bottom leg. You can ad more bottom legs as required for larger mainsails.
First the top leg of the Lazy Jack is riveted to the mast. the top leg consists of a single strop and a block at its lower end.
Second the bottom legs are attached to the boom and fed through the block of the top leg.
The bottom legs have a cleat to adjust line tension.
This diagram shows multiple lazy jack legs for larger sails. Y
You can see the extra legs support more sail area.
You can ad as many legs as you like, but I would follow the manufacturers recomendation.
Tips for installation
rigging lazy jacks
The best results with Lazy Jacks is by using full length battens. Short or regular batters end up getting caught in the Lazy jack lines. With full length battens they will not compress, so the batten tips stay aft of the lazy Jack legs.
When you hoist the mainsail the lazy jack lines should have some slack in them to let the mainsail set properly.
Harken Diagram, shows the lazy Jack legs being held outboard which helps separate the sail, from the Lazy Jack Legs
The boom cover will need to be modified unless you pull the Lazy Jack line lined forward after the sail has been dropped and secured. The modification includes slits and zippers or Velcro where the Lazy Jack Lines attach to the boom.
Lots of sailboat classes have descriptions on the Class forums about how to install Lazy Jacks or Dutchman systems.
It is quite feasible for you to make your own Lazy Jack system, many do. However buying a pre made kit takes some of the time out of the project.
Harken and Schaefer are two of the manufacturers for lazy Jacks. The Schaefer system is a bit more expensive, but has a feature allowing the lazy Jacks to be pulled forward which removes the need for boom cover modification.
Each have sizes based on boats length from 21ft to 48 ft. Both are available through the links below.
Most of marine stores have ready to go Lazy jack systems. All you need to do is install the legs, all the lines blocks and cleats are provided.
The Ezjacks system lets you pull the lazy jack lines forward. This enables you to use your existing mainsail cover. Otherwise you will need to modify you main cover with slits where the lower legs meet the boom.
Other Mainsail Flaking systems
Stackpacks were invented by Doyle sails as a way to enclose the mainsail after flaking in an easy manner. The mainsail cover is basically part of the system so you do not need to store and retrieve the cover every time you go sailing. The lazy jacks capture the sail as its drops and then all you need to do is zip up the top of the cover.
Introduced in 1983, DOYLE StackPack is the original trouble free mainsail furling system for the cruising sailor The simplest, easiest way to handle your mainsail Proven to be the most innovative and cost-effective mainsail handling system ever Maintains mainsail speed & shape - lies flat against the sail while sailing Available as a retrofit for your existing sail
StackPack is a fully battened mainsail with integral lazy jacks and a cover that opens automatically to accept the sail as it is lowered. The cover and lazy jack system neatly flakes and holds the sail as it is lowered or reefed. The folds at the foot of a reefed mainsail also lie neatly in the StackPack cover, eliminating the need to tie off the excess fabric with ties. With the sail completely stowed, the StackPack system presents a neat appearance and automatically protects the sail from harmful UV rays. While sailing, the integral cover lies flat against the foot of the sail for a clean aerodynamic effect.
More Sailmakers these days are producing their version of the stackpack, so ask your sailmaker.