David, who has a bee in his bonnet?

The fact that you 'should not wish to go to sea with a junk rig with balance area much in excess of 20%' is simply your opinion, and is not ' getting towards the top end of the range' as you quoted earlier. The fact that you hold this restricted opinion is up to you, but should not be used to mislead those who wish to look further and may be prepared to examine the full range of possibilities.

The figures I have quoted have all come from successful and stable rigs, one of which, I am informed, recently spent 3 days riding out a prolonged gale with no adverse effects.

For those who might be interested, in his book 'Design and Build your own Junk Rig' first published over 25 years ago, Derek van Loan described rigs he first designed in the '60's. The basic flat rig he suggested has 25% chord balance.

So let me repeat – 'Readers are advised to try to determine what is opinion and what is tested and proven fact over the 'full' range of possible answers.' Do not be mislead by the 'experts.'

Cheers, Slieve.

In post #6714642I Christopher Phillips wrote, “I have had to give the main a balance of 20% chord, which makes for about 17% area.”

In reply in post #6714919 David Tyler wrote, “20% balance is getting towards the top end of the range, but shouldn't overbalance and snatch, I don't think.”

This is typical of the 'miss information' or 'false news' which is being posted on the JRA website, and which can discourage members from experimenting and making advances in rig design.

Junk rigs have been sailing successfully and efficiently for a number of years with chord balance of up and including 35% with absolutely no sign of instability nor overbalance, and there are thousands of model yachts with balanced rigs which use 33% area as their design criteria for rig balance.

The streamlined symmetrical NACA 00 series foil sections do have a centre of pressure at about 24% chord, so it is possible that flat and therefore basically symmetrical rig may have similar figures, but it has been fully tested and proven that cambered soft rigs are fully stable with 33% area in front of the mast/ pivot point, provided that there is not a significant gap or extended moment arm.

It is wrong to mislead the readers by making statements about things that you have no personal experience of, and are only guessing at. There are too many instances on the JRA website of opinions being misrepresented as facts, so readers are advised to try to determine what is opinion and what is tested and proven fact over the 'full' range of possible answers.

Cheers, Slieve.

Christopher wrote:

I very much like Roger Taylor's "hinged" sail, although I seem to have lost the article from one of the yachtie magazines about it, which I kept.  Is Roger a member?

I'd love to hear from Annie if she has experience of sailing a junk Wylo - Nick tells me that there have only been a couple built so there's not a huge amount of experience to harvest.

Yes, Roger is a member. 

Hi David and Arne,

Thnks for your prompt responses.  Your suggestion to remain with the sail areas as drawn by Nick got me thinkng and looking again at the much-reduced (in scale) sailplan which I have available to me, and which I am using as a rough guide (I have seen the full-size drawings, but they are not as yet available to me all the time).  It seems that as well as the design peculiarities I mentioned in my post yesterday, having taken a ruler to the drawing, he has also drawn the sails slightly tapering from the boom upwards, the main boom being about 50cm longer than the top battens / yard.  Therefore, given this and the fact the masts have been bought to the vertical, if I draw sails to the standard PJR pattern, or to Arne's, with luffs and leeches parallel, the gap between the sails may increase sufficiently without having to fiddle with Nick's sail areas or increase the balance too much.  The mizzen as drawn has an AR of 2.4 against the main's 2.2, so making the mizzen 2.2 should help as well, abeit bringing the CE upwards a tad.  In answer to your question about the lead - as drawn by Nick, the lead is around 9%, which is slightly abaft that for the gaff cutter rig.

I note your advice to camber the sails by about 8-10%, which I will look at as well - I would be inclined to cut the mizzen flatter, especially as you suggest that the main might do more of the work! 

I very much like Roger Taylor's "hinged" sail, although I seem to have lost the article from one of the yachtie magazines about it, which I kept.  Is Roger a member?

I will definitely open a new thread for the boat - although at the moment the name is remaining under wraps (I know what it's going to be, I just don't want to jinx things by announcing it before the boat is 100% mine).  I'd love to hear from Annie if she has experience of sailing a junk Wylo - Nick tells me that there have only been a couple built so there's not a huge amount of experience to harvest.

Arne, thanks for the advice re the rudder.  This hull already has a rudder built and hung, so I'd be reluctant to start experimenting at this stage.  As designed the Wylo has a certain amount of balance to the rudder (I can't recall exactly how much).

I look forward to picking your collective brains further as the project progresses.

But I do think that Jami Jokinen's take on this method is further good step forward, with less potential for air leakage from windward to leeward side. It's a labour-intensive way of making the batten arrangements, but quite an effective one. Where it scores most, in my opinion, is on larger sails. Here, the sheer physical effort of shifting a near-complete sail around the loft floor and under the sewing machine would cause me to consider making it in two or three sections, joined by these hinges, but using one of the quicker methods elsewhere. On smaller sails, there's still a reason to use the method if the sail must be made in a confined space.

Can you please help me find information on Jami Jokinen's method for making panels? I have not found a good way to search for "all posts from this member" here on the JRA website.

I have been studying everything I can find from Roger Taylor. The separate panel sail construction in particular is very interesting to me.

Thank you  in advance for any information you can provide.

Scott.