Mack's OK
The Mackpack is a local sailmaker's answer to the Stackpack, and while it is not quite as well developed, it will work fairly well. If you have a great relationship with someone at Mack, that is what drives the decision more than anything.
Lest I be accused of making a vague and unsupported comment, I will explain the primary differences and why I say these things.
There are 2 key areas of difference-both of which in my opinion make a SLIGHTLY lesser product-and certainly much less expensive to build, and hence purchase:
1). In the Mackpack, the lazy jacks are passed through grommets on the sail cover, and then fastened (tied) to eyelets on the bottom of the boom, whereas the Stackpack lazy jacks are led to the TOP of the cover-with one end of each 2:1 purchase led to a small cleat sewn near the tack of the mainsail. The negatives in this (on the Mackpack) are that you have between 3-5 eyelets on the bottom of the boom-which are sources for chafe of Genoa and spinnaker/gennaker sheets, and potential headknockers, while the Stackpack has nothing screwed or riveted onto the bottom of the boom which could cause trouble, and even better, the lazy jacks can now EASILY be adjusted in tension right at the tack of the mainsail-where you are relatively safe. To adjust the tension on the MackPak you must untie and re-tie each end of the lazyjacks at each eyelet-while working upside down on the boom-sometimes near the end of the boom (to get a proper adjustment it is best to do this while sailing)- potentially not very safe. For the Stackpack you just go to the tack of the main and uncleat the line (one on each side), "season to taste", and re-cleat.
The other issue, and this is the one with the biggest cost impact (although you can see the Stackpack system is already more sophisticated, and those features cost more to build than going right to the bottom of the boom): The sailcover/cradle on the Stackpack is actually SEWN onto the mainsail! This is actually a pretty big deal, because without this feature, the cover can and will flap in the breeze-which can be noisy. The covers on the Stackpack lay flat (ish) against the sail and do not flutter in the breeze. Less windage, noise, and wear and tear=longer life and better performance. The method of attachment of the lazyjacks to the cover means that when adjusted correctly, the cover stands proud at anchor, since it is supported directly by the lazyjacks and the full length battens (which the Mackpack ALSO does not have) provide a great looking, non-baggy appearance. Take a look at the photo on the Mack website and you see a cover with that looks baggy and has the lazyjack lines laying against the cover, while if you look at the Stackpack website you see a more attractive, upright cover. Finally the Mackpack requires undoing one side of the cover to get the sail all the way down and put to bed, but because the stackpack stands up stiffly, and has access near the mast for this, once you have it adjusted right, the ONLY thing you have to do is unzip the cover and hoist, and to drop it, just let 'er down..if the slides are a bit sticky and you need to give them a hand, you do not have to loosen or "undo" anything-there is access already in the front of the cover.
There is nothing wrong with the Mackpacks-they work fine, and cost less because there is less to them. The Stackpack (again, when correctly set up, Guy!) looks better, lasts longer, does not flap in the breeze, and is functionally slightly superior. I think for their respective price points they are both great-but they ARE different. I NEVER want to type ANYTHING ending in "pack" again!
Puff pant,
S
