Arne wrote, “Could you elaborate a bit on where you have lowered the stress in the rigs with the profile (planform) you prefer, compared to the sails I design, with 60-70 degrees full-length yard (..basically the standard Hasler-McLeod sails with added camber...)? Should Zebedeeand Mingming II have their rigs remade?”

David replied, “Arne, This is simple geometry and trigonometry, and I'm not going to insult your undoubted intelligence by giving lessons in it. However, you might well read chapter 2, page 6 of Slieve's writings, where he describes how he developed the SJR planform by getting his model to hang as naturally as possible:”

David, you may not want to insult Arne's undoubted intelligence, but please explain the simple geometry and trigonometry to me and the other readers. I would like to see how you have confirmed that you have lowered the stress in the your rigs because I don't understand how you come to that conclusion.

When I first posted the draft notes on the SJR you criticized every aspect of it without any knowledge or experience of it, to the extent that I had to ask you to remove you posting, yet now you are quoting my notes but still not following them to achieve the low stressed rig that can result. I need help with the simple maths to be able to follow and appreciate you postings.

Cheers, Slieve.

Arne wrote:

Then Ketil Greve took contact last autumn, in need for a sailplan for his new Kelt 8.50. The mast position dictated a sail with a high balance, around 21-23%. To achieve that, I had to remodel the top three panels of the AR=1.90 master sail so the yard ended at a 60° angle.
As a result, Ketil, who made the sail himself, now sets it without needing a THP at all. I guess the upper batten parrel limits the forward movement. The halyard is next to vertical and the YHP is attached well aft of the middle. I sailed with Ketil after that little photo session. The sail went up and came down easily, and the lightly loaded Hong Kong parrels ensured each panel set well. A true Instamatic rig.

My conclusion is that the finer the halyard angle is, and the closer the CG of the sail sits to the mast, the lower get the forces in the parrel pair; the THP and YHP.

And yes, the top panels set just fine, both with 7-up and when 3-up...

Arne

So, Arne, you're heading in the right direction with Ketil's new rig. We're not really so very far apart, with your 60˚ and my 45 - 50˚. Could I urge you, please, to make this the standard geometry in all of your master sails, so that your audience of first time sailmakers are spared the trauma of having to wrestle with getting a rig with a 70˚ yard to set well?

Just find a way to dispense with that invention of the devil, the HKP, and all will be well. Give me a moment to think, now, how could that possibly be managed? ... I know! Hinges combined with only lightly cambered panels! That would do the trick!

David wrote:

It's a good state to find oneself in, to be content with one's rig!

So now, put on a windvane and some downhauls, and go for a long offshore passage - and then come back and tell us whether you're still content, or whether actual experience has modified your conjecture!  :-)  

Nope, I prefer pottering around on my home waters. It's as with music  -  taste differs.
My sailing in Ingeborg is more about smiles than about miles...

Arne

David Tyler wrote:

Arne,

....

As well as the stresses in the rig, there are the mental and physical demands on the stamina of the crew to consider. By your own admission, your sailing mileage on each outing is trivial, and so the work involved in keeping your rig set well makes trivial demands on your stamina. I ask you to accept that sailing continuously, day after day, through squally and variable conditions, one seeks to reduce those demands.

No, of course the rigs of Zebedee and Mingming II don't need to be reworked, so long as their skippers are content with them. Martin is not.

Mental and physical demands? What demands?

David, you keep telling me about problems I don’t have:
The procedure to go sailng goes like this:

• ·         I hoist the sail, preferably with the sail spilling the wind.
• ·         I use the YHP to position the yard so that the halyard’s slingpoint end up just aft of the mast.
• ·         I give the THP a moderate tug, and off we go.

There is no tweaking to be done with the parrels after that. The lightly loaded Hong Kong parrels sort out the setting of the lower panels. However, when I alter sail area, the YHP-THP should be dealt with. This is not critical, as it is more about cosmetics; getting the lowest batten sitting parallel  -  and a little above the reefed bundle. I doubt if this is much different from other rigs.

I don’t claim that my rigs are perfectly in balance (only square-sails are that), but the remaining imbalance  -  a result of having a fore-and-aft rig  -  is easy to deal with.

The only items I would add to make Ingeborg offshore-worthy, would be to fit a windvane and a couple of downhauls to let me reef while running before.

As for loads on the yard, battens and sailcloth -  I have sorted out this a long time ago.

Arne

Arne,

This is simple geometry and trigonometry, and I'm not going to insult your undoubted intelligence by giving lessons in it. However, you might well read chapter 2, page 6 of Slieve's writings, where he describes how he developed the SJR planform by getting his model to hang as naturally as possible:

"One clear observation was that when the yard was correctly set up the sail and battens simply hung down like a curtain with no significant forces to worry about. 

One clear feature was that the pressures on the battens were lower with the low angled yard and high sail balance rig compared with a high peaked Hasler-McLeod rig." 

As well as the stresses in the rig, there are the mental and physical demands on the stamina of the crew to consider. By your own admission, your sailing mileage on each outing is trivial, and so the work involved in keeping your rig set well makes trivial demands on your stamina. I ask you to accept that sailing continuously, day after day, through squally and variable conditions, one seeks to reduce those demands.

No, of course the rigs of Zebedee and Mingming II don't need to be reworked, so long as their skippers are content with them. Martin is not.