Stack pack - under or over boom?

[Tillsbury]

Originally Posted by CassidyNZ

I think it’s very doable to sling the stacpac under the boom. My only question really is “Is there any advantage”. Mine is fastened to the top of the boom with a bolt rope and slides. I can’t think of anything that would make it perform better being under-slung and getting to reefing lines etc. would be considerably harder.

The advantage (it seems to me) is that the mainsail already fits over the boom, and except near the mast it doesn’t take up any significant vertical space. I.e. the windage (or aesthetic) of the boom and sail packed down isn’t much more than the boom alone. If I built a stack pack sitting above the boom then it would naturally sit much higher overall.

When the sail is down I want all the reefing lines to sit in the bag out of the way! My third reef is very deep so there’s a fair bit of string around when the main comes down — I want that all to disappear in the bag.

[gruffa]

I think it could be a great idea. I am a sailmaker and hadn't thought of that. Thanks!
I agree it might be good to keep the overall size and windage down. Should be no trouble setting it up. Only thing is to consider your reefing arrangements.

[CassidyNZ]

Originally Posted by Tillsbury

The advantage (it seems to me) is that the mainsail already fits over the boom, and except near the mast it doesn’t take up any significant vertical space. I.e. the windage (or aesthetic) of the boom and sail packed down isn’t much more than the boom alone. If I built a stack pack sitting above the boom then it would naturally sit much higher overall.

When the sail is down I want all the reefing lines to sit in the bag out of the way! My third reef is very deep so there’s a fair bit of string around when the main comes down — I want that all to disappear in the bag.

Mmmmmmmm. Thinking about that, my reef lines come out through slots in the side of the envelope and there’s always a bit of stretch damage to the edges (which I’ve had to reinforce with leather). Your design would have all the lines already inside the envelope. More durable.

I guess the only limitation would be working with the lines (replace, repair) but that’s once in a while at which point the envelope would need to be dropped away.

My main is on Harken Batcars so the main near the mast is in any case high profile and the advantage of lower profile is not a benefit for me.

So my last question would be around how to attach the stacpac to the underside of the boom.

[senormechanico]

Pics above show common sense fasteners. Post 28.

[Tanqueray]

I don’t know that it matters of the stack pack runs under the boom or on top. Seems to me that there is a lot of stuff to work around if you go under the boom...Vang, main sheet, lazy jack lines, etc.

I have a Mack Sails Mack Pack and I really like it. My main sail has a rope bolt, and the cover is held in place by 4 or so pieces of Dacron that slide into the boom groove, and are held in place with the sail. I can pull the jacks forward to the mast when sailing, and roll down the cover if I want to get it out of the way. I don’t usually do that for a 4-hour sail. Remember, I bought the system because I am LAZY.

I am waiting for a new main sail to be delivered. I went with a loose foot this time around. I intend to keep the sail cover attached just as it now. If I have to, I will run a rope form in the groove to hold the cover in place. But I don’t think I will need to do that.

Videos

Greg

[NevilleCat]

I'm pretty sure the only boat I have converted to a stack pack about 20 yrs ago had the thing mounted underneath the boom with cut outs for mainsheet and vang and drainage. The lazy jacks were attached to sewn in pvc battens at the top of each side of the stack pack. The foward section of the stack pack was a removable bonnet that zipped around the mast so that was taken off when under way. My reefing lines came forward to the front of the boom so ran inside the pack no problems. It was easy to set the lazy jacks with the right tension so they didn't have to be adjusted at any time.
Just assumed they all were this way, but it was only a 30' boat so maybe different with a bigger sail to deal with.
The only thing different is reefing, where the luff cars all stack up as you don't exit them out of the mast gate so you can't use the boom horn and it means the boom tends to be higher at the aft end on deeper reefs to match, just looks a bit different, (I just had two deep reefs in the new sail instead of three as I was going to have the reefing lines run back to the cockpit but too much friction in that system so reverted back to doing it at the mast.)