The posting I have just put on the 'Split or unsplit, that is the question' thread might have been more useful if posted here.

Cheers, Slieve.

Anonymous wrote:

It hasn’t been done before on a SJR (as far as I know) and when you stop to think about it, it vastly complicates the design. Unless you use the vertical drawing and then just tilt the whole thing just a very small amount. Why bother?

Tilting the whole thing is how it's done as far as I'm aware. I find it hard to believe that the SJR hangs from the yard naturally aligned in its final intended position, junk rigs in general when hung from the yard without any supporting rigging tend to hang forward of the mast so you need various parrels to "pull it" aft to its intended position.

If you had a sail with 50% balance and hung it with the yard attached in the middle it would hang pretty straight but this is not the case with Poppy's sail at least.

Why bother? Because one highly appealing aspect about the junk rig for me personally is that with a forward raked mast the sail will "push" itself out in ghosting conditions (esp. with the wind abaft the beam), something which is a huge annoyance with bermudian rigs flopping about.

It just happens that gravity is a vertical force. Not having "come up through the ranks" of conventional junk sails, getting a junk sail to set nicely is something I don’t know much about, but my gut feeling is you might be diminishing a rather significant advantage, in order to gain a different very small advantage, and simply adding an unnecessary complication. I am not sure, I don’t know enough. Give it a try!

I will! :) I have in fact just purchased some sticks and strings and will be building a model rig soon. There is surely a point where adding more rake will start causing issues but I don't think something like 1-3% would cause any. I might be wrong though. And I would love to be enlightened if someone here has any good input on the matter. And however that may be I might have some answers myself soon.

PS. This WYSIWYG editor is driving me crazy.

Thanks for the clarifications Graeme!

Problem is then how you would properly establish the CE/CP in order to get the correct lead (another fuzzy concept) for the rig. There is nothing difficult or “fuzzy” about this, other than the need to realise that there is no such thing as an actual centre of effort or centre of pressure.

In regards to "fuzzy" this was exactly what I meant, that we calculate lead based on CLR and CA (center of area, not center of effort/pressure) and that this is a huge simplification since the actual CLR and CE start changing as soon as the boat starts moving. Experienced designers end up making an educated guess with lead based on hull shape, type of keel/rudder, type of rig/sails etc, all of these coupled with experience. The recommendations in PJR assumes flat sails so the best for those who have cambered sails is to read up on other junkrigger's experiences and then make educated guesses ourselves. I think that falls into the definition of "fuzzy". :)

Anyways, it's not highly relevant to the discussion here.

I'm considering converting my current boat to split junk due to the split (or aero) allowing the most balance and thus the best mast position without having to make considerable modifications to the interior. From some quick sketches I would need something around 33-35% (including the slot).

Now, that makes sense and I think you are on the right track. Assuming you are converting from bermudan rig to any of the well-proven junk variants, I am sure you will be delighted with the result, best wishes.

Thanks! This will in fact be my second JR conversion. The previous one was in 2015 where I was first going to build a wingsail but in the end - due to lack of time - opted for a flat sail with hinged battens. This worked quite well and I was happy with it but ended up selling the boat shortly after due to moving abroad because of work.

I've been aware of the SJR ever since I got introduced to JR back in 2010 or so but back then I believe Poppy was the only one sailing but now over the years the SJR seems to have caught on and established itself as a quite well working rig.

As my life situation has changed again and I now have the opportunity to mess around with boats and rigs again I ended up buying a 28 footer (similar size to my first conversion) last summer. With a traditional JR the mast would end up right in the middle of the V-berth, which is what I did with my last conversion, but I don't want to do it this time around - I would like to keep the mast as close to the original (keel stepped) mast position as possible, thus keeping the accommodation more or less as-is. And to achieve this I don't see many other (or better) options than a "highly balanced" rig, of which the SJR seems to make the most sense. I've sketched various multi-masted rigs but haven't really been happy with any of them, so at this point SJR is the most likely candidate.

A small disadvantage of the SJR rig is that, so far at least, they have all been designed around an assumed vertical mast, for obvious reasons of simplicity - so with the split rig we don't get that extra, little benefit.

Why is this though? At least it's not obvious to me. What would be the problem(s) with raking the mast a degree or two forward?

Comparing split and unsplit is probably getting a bit off-topic and it wasn’t my intention to open that up. But you make some very good points Arne and although I am not qualified to make comparisons, it’s a discussion I sure would love to have with you because I thought long and hard about building one of your rigs and sincerely wish I had the time and the years left, to do so. So much still to learn… so little time! Obviously, Robert is interested in this question too. I’ll be bold and open up a new thread.

Graeme

I guess I have three reasons for sticking with the un-split Johanna-style rig.

·         It is faster and more forgiving to produce. Each panel of the SJR has two luffs. To keep both luffs straight, both has to be exactly the same lengths (..however, as I write this, it strikes me that one could possibly adjust slack luffs with a quick lashing...).

·         I am unsure if the SJR is any faster to windward than the Johanna JR ( or any one-piece, cambered JRs). My experience is that the Johanna JRs are just about as close-winded as Bermuda rigs. The split JR may well be more powerful over-all, but being a fjord sailor, my first priority nowadays is on VMG to windward. Any JR do well when reaching and running.
Note: I said I was unsure. One day it may be proven that the SJR outperforms a well-made, ordinary cambered JR to windward  -  or not.

·         The 70°, full-length yard ensures a long luff and maximum sail area on a not so tall mast. With all the bridges in my area, it makes sense to avoid tall masts. In addition, in the summer season, we often have quite light winds early in the day, so a decent sail area is very welcome.

Finally, what you describe about downwind sailing in your PS; echoes what Slieve McGalliard once told about his Poppy.

Arne