I liked David T.’s  gentle modification to the Amiina Mk.2 SJR, so now I have scaled it up and plonked onto that poor Seal 36. This puts the mast even further away from the bow.
I am unsure of where the exact fore-aft position of the sail should be. Same with mast length. Tell me what halyard angle is acceptable.

Btw. I just had a look at Martin Brown’s Custard; the latest Boat of the Month. By raising the yard angle, he has in my view solved the halyard angle issue. I guess I have to make another mod to David’s SJR...

Cheers,
Arne

(Full size diagrams in Arne's sketches, Section 9)

What a good outcome this thread would be to get something like this document produced.

I'm young and hardly rich in time with a job and three young kids, but my fingers still work and I have experience in creating documents etc. I'm happy to put my name down to help create the document. We could have it as a Google doc or similar that would allow easy access for contributions from more than one person. Also, perhaps for those who would benefit, I could transcribe from voice recordings too, maybe better than AI as I'll understand some of the technical words. I don't have a good drawing program so Davids help here would be helpful. 

And a last thought, if I end up undertaking the process of converting the Seal to a SJR then I could document the process with great detail to accompany the build notes. 

It also means a lot David to hear your positive words about this rig being something you would install if you had the time and ability. My first junk exposure was on Tystie with Gordon that helped cement the desire to rerig.

Slieve, the only fault that I can see certainly applies to me and others as well, and simply put, it’s that we’re all getting older and can’t do as much as we used to do. In my case, Parkinson’s makes it extremely difficult for me to write accurately; but I can still draw (so long as I’ve taken my medication!). That’s why I think that there needs to be a collaborative team effort here, pooling skills and resources to ensure that everything that has been learnt about SJR is recorded into a useful document. You have passed on your knowledge to those members who have built SJR rigs, and it is now those members who should really be stepping forward to make a good record all that you’ve taught them, in order to pass it on again. By all means do as much as you can, but I don’t see why it has to be a solo effort. So come on, all you SJR sailors, it’s time to get to work! 

Anonymous wrote:All this discussion is leading me towards the view that there really ought to be a document on this website detailing the current state of the SJR art, building on Slieve’s original rough draft notes, and adding all that subsequent practitioners have proved to work. For example, I can find the broadseam calculator spreadsheet, but no notes on how to use it, and I don’t think that it gives dimensions for a mk2 sail. I can’t find notes on actually building a complete sail and rigging it, as the rough draft is incomplete, and it doesn’t give full explanations for some things that are advocated, such as the jibs being on the starboard side of the battens (this puzzles me). I’d certainly like to see a spreadsheet for the mk2 sail, and will undertake to develop a version of it with 5 parallel panels / 6 sheeted points, as a generic 2D CAD drawing that can be used to design and make offshore cruising sails. Like Slieve, I’ve retired from active sailing, but if I were still able to make a rig, put it on a boat and use it offshore, this would be what I’d favour, and I’d want to be able to access a full set of sailmaking instructions for it, as Arne has done for the kind of rig that he favours. If a wordsmith amongst us (Graeme?) will undertake to gather the info and draft such a document, I’ll undertake to employ such skills as I’ve acquired in 3D CAD modelling to illustrate it. 

What a beautiful idea David!

I think that many JRiggers would devoure such a writing.

I certainly would....

Mauro

Slieve wrote:

Hi Thomas,

There are an interesting number of points here, and possibly some simple answers.

Firstly, I don’t see why the Mk2 rig would not scale up well to 65sq.m. I have a spreadsheet which will give all the dimensions for that for the ‘standard’ shape (though I would have to check that is is complete) if you would like a copy. It may even give the broadseam depths and widths if going that way.

As to whether to add another panel my answer is that I would not like to increase the aspect ratio too much, so might draw a rig only half a panel taller and split it into 5 parallel panels, but I will admit that I feel that 5 panels given enough reefing steps because of the rigs apparent tolerance to sail area and the advantage that with split sheeting with 2 battens per sheet then the twist can easily be controlled when reefed.

As for additional controls for long distance cruising, the minimalist controls is one attraction of the rig. With no Hong Kong parrels, luff hauling parrels, fan up preventers you are left with a halyard, a pair of sheets, three or four combined downhaul/ batten parrels and either a yard hauling parrel or another downhaul/ yard parrel to make it work. In practice I would add shortish batten parrels to at least the top and bottom battens and to the yard for added security, and would discuss with David his comment on securing the boom (bottom batten).

One thought I have had for long distance sailing on a junk would be to have a detachable water sail which could be clipped onto the bottom batten and held down against the deck with bungees through rings stretched from toe-rail to toe-rail. When sailing in light conditions closing the gap below the sail could give some extra drive. It could be made from spinnaker material, with a couple of small areas of window material and probably not need a slot. But as I say, just a thought.

As for working out where the CoA of the existing multi headsail rig is, count me out.

And don’t forget, I’m biased.

Cheers, Slieve.

All this discussion is leading me towards the view that there really ought to be a document on this website detailing the current state of the SJR art, building on Slieve’s original rough draft notes, and adding all that subsequent practitioners have proved to work. For example, I can find the broadseam calculator spreadsheet, but no notes on how to use it, and I don’t think that it gives dimensions for a mk2 sail. I can’t find notes on actually building a complete sail and rigging it, as the rough draft is incomplete, and it doesn’t give full explanations for some things that are advocated, such as the jibs being on the starboard side of the battens (this puzzles me). I’d certainly like to see a spreadsheet for the mk2 sail, and will undertake to develop a version of it with 5 parallel panels / 6 sheeted points, as a generic 2D CAD drawing that can be used to design and make offshore cruising sails. Like Slieve, I’ve retired from active sailing, but if I were still able to make a rig, put it on a boat and use it offshore, this would be what I’d favour, and I’d want to be able to access a full set of sailmaking instructions for it, as Arne has done for the kind of rig that he favours. If a wordsmith amongst us (Graeme?) will undertake to gather the info and draft such a document, I’ll undertake to employ such skills as I’ve acquired in 3D CAD modelling to illustrate it.