Lazy jacks can be one of the most complicated rigging systems on a trailerable sailboat but they have a simple function. That is, to cradle the mainsail when it’s lowered so that it doesn’t spill onto the cabin and cockpit. If you usually have another experienced crew member aboard, that person can gather and tie down the mainsail and you don’t need lazy jacks as much. But if you often sail short-handed or are just plain lazy, lazy jacks can make coming to a dock or anchorage a smoother, more pleasant event for everyone and it helps protect your mainsail.
There are many lazy jack kits available, from simple stationary setups designed for boats that spend most of their lives in slips to complicated retractable systems that you can work from the cockpit. A certain online Catalina parts retailer offers a simple but expensive kit specifically for the C-22 . The problem with most systems is that they aren’t designed with the trailer sailor in mind. Either the lines fasten to the boom, which needs to be removed while trailering or they fasten to the mast and you need to reeve the lines through fittings on the boom in order to set them up. Anything that takes more time during setup means less time sailing and is the enemy of a trailer sailor.
Rock a bye, mainsail
The only system that I’ve found that combines good function with trailering convenience is the Sail Cradle Mark IV from SailCare. It’s made partly of regular rope and partly of shock cord. The rope lines form an inverted Y at the top and fasten permanently to the mast like other systems. The unique part is the shock cords that form an M shape at the bottom. You temporarily attach these to hooks and eyes on the boom during use. When it’s time to haul out and go home, you simply disconnect the shock cords, stow the system tight against the mast, and the boom can come off without any dangling lines attached. For a video of the system in action, skip ahead to 3:10 in this YouTube video of the system installed on a MacGregor 26M. The design is so clever that I built a set myself on Summer Dance at a fraction of the price.
Geometry 101 revisited
The trick to this project is determining where to mount the hardware on the mast and boom and how long to make each line. The length and position of each line is important if the lazy jacks are going to catch the mainsail or just deflect it onto the deck as usual. It’s also important that the mainsail batten ends don’t catch in the system on the mainsails’ way up or down.
Thankfully, there are standard formulas that you can use as a starting point and then fine tune depending on the specific sail, its battens, and so on. Using the C-22 P dimension of 21′ and E dimension of 9.66′, here are the formulas:
Top of first segment: P * 0.70 = 14.7′
Height of first segment (and first cord length): P * 0.25 = 5.25′
Height of second segment (and half of second cord length): P * 0.25 = 5.25′
Mid-boom attachment point: E * 0.40 = 3.86′
End of boom attachment point: E * 0.85 = 8.21′
These dimensions basically divide the mainsail height into quarters with the lazy jacks spanning the lower three quarters. And it divides the mainsail width about in half with the lazy jacks spanning the whole width.
To obtain the shock cord length, I temporarily rigged the bottom segment with regular cord, measured the length of that cord and then subtracted two feet. With the shock cord that long installed, I stretch it about one foot to pull the middle of the M shape down to hook it onto the hammock hooks I show below. Depending on how stretchy your shock cord is, you might want to subtract more or less. Start by subtracting one foot and test the system for a while to see how well it works. Then if you want to make it tighter, you can shorten the shock cord more.
In the following pictures, the upper and middle quarters are made of blue rope and the lower quarter is made of white shock cord.
Shock cord and awe
On Summer Dance, I attached the top segments to the mast with eye straps angled 15 degrees down and aft (to bisect the lower segment). I tied nylon thimbles into the ends of the line segments with fisherman’s knots. Each middle line segment is one piece of line 10.5′ long. Each segment is able to run freely through the thimbles of the adjacent segments. This lets the system adjust to different boom heights, angles, and it lets the system stretch for storage.
I attached the stationary ends of the shock cords to eye straps angled up and aft on the mast at about boom height.
I mounted hammock hooks on the boom 4′ from the mast. This location seemed to hold the middle battens best.
At the end of the boom, rather than drill more holes for more hardware (on Summer Dance, it’s pretty busy there already if you look at this picture), I simply threaded a loop of cord through holes molded into the fairlead cleats that were already in about the right location. Hooks in the ends of the shock cords clip into the loops on either side. If you don’t have cleats at the end of your boom, install a pad eye on each side instead.
Tweaking with twings
During testing, the mainsail battens fouled in the lazy jacks more often than not since the lazy jacks were only a few inches apart to start with. So I rigged twings from the ends of the spreaders to the upper eyes to pull the lazy jacks apart about 2′. This forms a sort of funnel (as you can see in the first picture) and gives the mainsail plenty of room to flail around without the battens fouling.
The sail cradle/lazy jacks work well out on the water. I can point Summer Dance into the wind and drop the mainsail neatly into the cradle in seconds. When we’re tied off at the dock, the cradle makes flaking the mainsail properly easier than before because it’s partly done already.
The beauty of the system is really in the shock cords. For stowing, you can stretch them to hook onto whatever hardware you already have that is convenient. When I have the mainsail tied up and covered, I simply unhook the middles of the shock cords from the hammock hooks. This slackens the whole system so that it’s out of the way when it comes time to hoist the sail again and the lazy jacks don’t affect the sail shape. I can also pull the slack down for the night and loop it under one of the cleats on the mast to prevent mast ringing.
When it comes time to put Summer Dance on the trailer, I unhook the ends of the shock cords from the boom, clip them into the lower eye straps and loop the slack under the mast cleats. This holds the whole system neatly out of the way until next time.
Without the expensive blocks or cables used in other systems, all the parts of this design (about $30) are easily and economically replaced as needed.
I’ve been using this lazy jack system continuously for five years and I still like it. The shock cord hasn’t yet stretched to the point where it needs to be replaced yet and the rest of the system hasn’t experience any noticeable wear.
If I had to do it over again, the only modification that I would make is to eliminate the top segment entirely and instead secure the middle segment to eye straps mounted at the midpoints of the spreaders. This would simplify the system a little and it would solve one small problem.
It would simplify the system because, besides the top segment, the twings would no longer be necessary. The spreaders would hold the lazy jacks open instead. See the picture of the spreader above for how close to the spreader the top of the middle segment is already, only inches away.
And the problem is that, after raising or lowering the mast and when walking the mast forward or backward, the top segment won’t pass through the mast crutch without manual help. That means either another crew member has to help out or you have to lay the mast down, pass the upper segment around the mast crutch yourself, and then resume stowing the mast. Eliminating the upper segment would also eliminate this problem.
But other than that modification, I wouldn’t change a thing.
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