I like that I could use the smallest size and that it is slippery enough that Brummel loops will be as good as mini blocks.

Any downside?

I would have used stainless steel rings instead of mini blocks.
Coated Dyneema (like Amsteel blue) will give friction and wear when sliding across the rope.

I agree that it's easier to splice and that you can go down in size is good.

My lazy jacks is made of normal double braid with SS rings.
The rings are easy on the sail with negligible friction.

Spliced eyes and ring hitch onto the ring, for easy assembly/dis assembly.

 

The coloured Amsteels do shed their color so you might consider grey. I've been using 3mm grey for my jacks for about a year now and am very happy with them

The way mine are made up is that they go under the bag, around the boom such that they hold the bag to the boom. I have them fastened to tabs on the stack-pack so they have tension to hold up the bag when deployed

this is the only pic I have of the jacks. What you can't see is that along the top of the bag, instead of battens and straps to tie the lines to, the lines you see are run through grommets which have plastic balls knotted to them at a length such that when tension is brought on to the jacks, the bag is held up, but the line length run under is left slightly loose as you can see

 

I think I understand how you have your lazy jacks run through the stack pack which sounds exactly what I want to do. I started with lazy jacks, later fabricated a stack pack and then took it off because I did not like the battens which were a mess while sailing. I want to go back to a stack pack and would love to see more pictures of your arrangement. Would you mind?
John

 

Here's another picture that's here at SN. In this picture, it's actually the 'old' pack which was a Mack made one that I modified. The closer-up pic posted above is of the pack that I built from scratch (note the lighter blue color). Lemme take a minute and look for other pics, think I've got some at F'book

http://www.sailnet.com/forums/membe.../forums/members/multihullgirl-albums-pics-picture6682-avighnajuana2013cropd.jpg

Here's the best pic I have, just found. The pack isn't finished mounting, as the fasteners which attach the front of the pack to the mast aren't installed, hence the mainsail luff is showing but if you look in the above picture you can see the bag closes along the mast with twist fasteners and a hook. The whole mess can be dropped and tied down for racing, although as you can also see above, half the time we don't bother with it and just let it flap

 

I'm using the 3mm amsteel grey with ronstan shocks as the "sheaves" rather than either rings (large and unsightly) or sheaves (large with moving parts).
Just use a knot compatible with the slipperyness of the line like an estar hitch knot as shown in amimated knots by grog.
Regular knots will slip with the higher tech materials like dyneema leading to a trip aloft to re-feed your rig.

 

Multi, thanks. Since I don't race, i would almost always sail with it on and not tied down. With a batten, the one I made just had too much bulk flapping around. I'm hoping that without the battens the windward side will lay against the sail and not create a lot of disturbance.
Thanks for your posts.
John

 

I am using 1.8mm dyneema with small stainless rings for lazy jacks. I tried just using an eye splice, but they bind up with any load put on them. They are so light any breeze at all will blow them free of the main. Works great.

 

I happened to be at the boat, so I took some pictures. As was mentioned, small rings do work well with Amsteel. I happened to have blocks from the jacks that I was replacing so one termination is with blocks, but the second termination is with small rings.

The bag's zipper is a continuous line, run to blocks and through thimbles whipped to the bag. Handsome Husband the Deckhand Boy likes the zip rig very much.

The jacks themselves:

Lazy bag pictures, fore to aft:

 

I just replaced vinyl coated wire and bullet blocks with small diameter Amsteel and Antal low friction rings. Light, simple, strong ... works great.