Extraordinary Sailmakers

Mack Pack

The Mack Pack is a semi-automatic mainsail cover and lazy jack combination

Travis & Colin Mack of Mack Sails

How to Use and What to Expect

Setting the mainsail has never been easier.

The Mack Pack has a zipper closure running along the top length of it, connected to a continuous line running to the mast. To set the sail pull on the line to open the cover. Then attach the halyard to the headboard. Now it’s a bit tough to be fast enough to raise the sail up through lazy jacks without catching a batten on one of the lines, so reach back about three feet to the cleat on the boom holding the leeward control line.

Make a permanent mark on the line at the cleat so you will know where to re-cleat it after setting the sail–because the boom will be slightly higher when sailing than when at rest.

Then raise the sail, right out of the Mack Pack.

Very simple.

  • Go to the mast
  • Unzip the cover
  • Attach the halyard
  • Slack the leeward jack
  • Raise the sail
  • Re-cleat the jack line
  • Go sailing

When sailing,

we often leave the front of the cover fully attached to the mast. If we’re going on an open water passage, or if the wind is up, we unhook it and roll the front of each side down to the ties provided. When we need to reef we lower the sail to the luff cringle, hook it, retention the luff of the sail–then, (we have external reefing lines to a winch on the boom), we hook the cover back up to the mast so it cannot get caught in the outhaul reefing line–then we crank the new clew out tight, re-tie the cover down and off we go. The lazy jacks contain the bunt of the sail, so there’s no need to tie off the individual reef pendants.

When sailing is done,

we more or less reverse the procedure, leaving the top of the starboard side of the cover down so we can jam the slides and battens all the way down, then hook it back up. Our new and firmer Spectra/Mylar mainsail is a bit tough so we have to help the excess sail into the cover in a few places before we can zip it closed, but this is a small inconvenience compared with having to furl the thing, find the gaskets and tie them off, dig out the cover and try to install it over a 9′ x 9′ Bimini top, etc., etc. Note: You should be head -to-wind when dropping the sail or, lazy jacks or not, the sail will be all over the place.

There’s another benefit to the Mack Pack not to be overlooked.

We cruise the Bahamas almost every summer for about a month. Like many sailors, we have been less than religious about installing the sail cover after a day’s sail to another island, or wherever, and sometimes several days in between. With the Mack Pack the sail is covered anytime it is not in use. Depending on one’s boat use, a Year’s worth of UV exposure can easily be saved over the life of the sail.

We unconditionally warranty the Mack Pack for 18 months.

We recommend, for ocean crossing voyages, that the cover be rolled down tightly to the boom and the lazy jacks led forward to avoid chafe. The cover is sewn in UV resistant GORE® TENARA® thread and the zipper is buried in the hem for least exposure to UV. We will replace the zipper and refurbish the cover for $150, incl. UPS back, to anywhere in USA. This offer good for 6 yrs.—useful life in 12-month use: 8 to 10 years.

The Mack Pack is not part of the sail. It is completely separate from the sail and is best described as a glorified sail cover — with integrated lazy jacks.

How to measure video, instructions & form

Attach tape measure firmly to topping lift at a point 12″ above the boom. From there measure forward to the top of the mainsail at the sail track, then forward to the tack of the mainsail at the intersection of top of boom and the back of the mast. DO NOT PULL, DEFLECT, BEND the topping lift forward when you do this or your dimension (and the cover) will end up too short. Best to super tighten the mainsheet to load up the topping lift before measuring.

Now measure from top of the boom, at the mast, to the top of furled sail, at the mast. DO NOT ADD ANYTHING—we will add to your measurement to make room at the top.

If you want a really nice installation, or don’t have a topping lift, we offer a stand-up bracket that mounts at the end of the boom. The cover is tied to this instead of the topping lift. Standard bracket is $150, Tall bracket is $160.

We will add a flap to the length dimension so that it will install just onto the mast by about two to three inches. we assume there is no obstruction in this area.


If your slide does not appear in the form below, don’t worry – just give us a call at 772.283.2306

How is Main attached to boom?

If it is a flat slide, measure the width and then choose option below:

If it is round slide, measure the width and then choose option below:

10 + 4 =

Tap image to Download


You should have a topping lift. If not, you can rig an auxiliary main halyard (good idea anyhow) and lead it to the end of the boom.
If you have a rigid vang and do not wish to rig a lift, then we offer this devise to fasten to the end of your boom–to hold up the back end of the Mack Pack — Standard bracket is $150, Tall bracket is $160, or you may contrive your own.

Not compatible with roller reefing booms. If you wish to roller reef, the Mack Pack is not for you.

The Mack Pack is compatible with mains with loose foot, bolt rope or foot slides, you just need to let us know what configuration you have.

Comes only with our lazy jacks. We cannot accommodate previously installed lazy jacks.

In use, the Mack Pack is open on its top, back and bottom so it will not interfere with most jiffy reefing systems.

Open bottom design allows for good drainage of rainwater and better ventilation.

MACK PAck Pricing

Prices Complete Ready to install with all fasteners and instructions

10-12′ BOOMS $1080

13-15′ BOOMS $1160

16-18′ BOOMS $1240

OVER 18′ ADD $45 per FOOT


(Price includes up to 48″ for ‘A’ dimension. Measurements above 48″ luff, add $8 per foot to the price.)

We will measure and install locally, Vero Beach to West Palm Beach area — $400 additional.

Florida residents add sales tax.

About our Mack Jacks