Anonymous wrote:

Thanks Paul,

That was indeed the trouble I was running into.  For the yard length, yard angle and halyard angle PJR works for the standard Hasler-McLeod sail, but isn't always straightforward for other sails.  Would you agree with the below guidelines:

1)  Regardless of Yard Length (e.g. if your yard is shorten than the battens), the sling point for the yard is somewhere close to the middle of the yard, perhaps slightly aft (55%) to aid in peaking the yard.

2)  The halyard should be as close as practical to being in line with the mast when the sail is at full hoist.  I think David Tyler and Arne use a guide that the halyard should be less than 30^o to the mast centre-line, but less is better.  The lower this angle the lower the forces for getting the sail to set nicely, you've been an advocate of this approach Paul.

3)  PJR gives a pretty generous halyard-drift (distance between sling point on yard and masthead).  Arne uses 600-700mm as a minimum and David Tyler has suggested if just two blocks are used you could get away with as little as 500mm.  More drift is better than these minimums.

3)  If you set the yard angle, then that and the above rules give you a narrow range of sail balance on the mast.

Yes, you have got it.

For halyards, I follow David and use a three part halyard as I find it mostly has enough power and its a very convenient arrangement. I find that if I secure the standing part of the halyard around 5% to 10% of the yard length aft of the yard center, there is no need for a throat hauling parrel. I've attached a drawing to show what I mean.

I also now use a very simple mast head arrangement... the drawing should be self explanatory.

Anonymous wrote:

Paul,

Are you talking about using Fig. 6.28 (Limits of Mast Line) in PJR?  It looks like you are using the batten length of the lower battens as in PJR, and the distance from the sling point to the mast centre that would give, but maybe cheating the halyard drift compared to what you would get from the calculations in Fig. 6.28?

In practice the halyard lies very close to the mast and if you don't let it or allow for that fact, you will struggle to get the sail to behave. I have not bothered with all the little rules in PJR and have not for a long time. I've done enough sails that I pretty much know whats going to work or not. The fanned type sails only more or less follow the PJR rules , so for them, PJR is not set in stone. Of course the rules do apply if you are building a true Hasler sail.

Anonymous wrote:

This topic has had some of the best info I've come across on Yards and Yard Angles and with so many of the Junk Heavyweights contributing, I feel I must  be missing something basic because I still don't quite understand.  I think I understand PJR, Paul's and Arne's rules about Yard position and Paul's excellent diagram on page 17 of this thread makes balance for a given yard angle easy to figure out.  But, as near as I can see, the discussion earlier in the thread assumes a yard of equal length to the battens, and hoisting the sails as high as practical on the masts.  What happens if you shorten the yard and give up a bit of mast hoist?  Can you then have less balance for a lower yard angle?  You lose sail area, but you save weight aloft (yard goes from 12.5kg down to 8.5kg in the example below), and maybe the shorter rig would be a bit more efficient to windward while the taller rig has advantages downwind.  I assume that the shorter and lighter yard would be easier to handle.  So, have I missed a rule? 

Essentially the same rules still apply. Why? Because you want the sail to "hang" from the halyard attachment point in a manner that has it nearly where you'd want it to be. The closer you can get the sail to just naturally position it's self in the needed position, the easier it will be to get the sail to set well.

Shown is Almanda's (formally Le Canard Bleu) sail plan. You can see that even though I've used short yards, I've still followed the rules....

A special forum for historic junks - Yes Alex, that is a nice idea.

A good source for starters is a 2002 PhD thesis entitled "Misunderstood Junks" which can be found in the JRA Library, the link is here. 

Regarding Amoy, here's a couple more: here  and  here.

Amoy

Thank you Alex those photos interested me a lot. I looks like a lot of hauling gear utilised to set these sails, including HK parrels - and peak halyards? Anyway, the middle photo, with the boat actually under sail, clarifies that when under way, the yard angle is not quite as low as it appears in the "in port" photos, and balance is not that great either, from this photo. Flat sails, of course.

I suspect now that in the photos near the dock they are probably just drying the sails, rather than deploying them for sailing.

The Amoy made her Pacific crossing in 1922, with crew comprising Captain (George Waard), his Chinese wife Choyee, their 10-year old son and three Chinese seamen. According to Waard the Chinese crew “deserted as one man” when they arrived on the West Coast. When the Amoy reached San Francisco, Alfred Nilson joined the family. He sailed with them down to South America, through the Panama Canal and up the East Coast. Nilson and his wife then bought the Amoy and raised 3 sons aboard her. The boat was a floating art museum that Captain Waard and later the Nilson family exhibited to thousands of visitors. In 1961 the Nilsons sold the Amoy. That same year she was lost in a storm near Cape Hatteras.

Nilson claimed that Amoy was "steady in all kinds of weather because a huge air pocket in her stern can absorb up to a ton of water..." 

Quite beamy for a junk. What a sight she must have made.