Anonymous wrote:

Embarrassed of cambered panels, here we go again...

David Thatcher wrote: «With the sail up in no wind conditions I was always slightly embarrassed by the wrinkly bag of 'Footprints' sail, but...» The same has been expressed by other JRA-members, among them, Shirley Carter on Speedwell.

Back in the beginning of this century, the photo below to the left (from 2000), was shown to the members of the Yahoo JR group, and there was a lot of cheering and hoorays. Then, a few days later, the photo, below, r. was uploaded to the same site. This photo was taken a few minutes after the first one and shows Samson when he runs into a wind shadow, and the panels are deflated. It clearly was a shocking sight. Words like “terrible” and “bloody awful” was sometimes used. It seems that that many were put off from cambered panels by this photo, and rather turned to hinged battens.

I remember that I then thought to myself: “Have they ever thought of how Cutty Sark’s sails may have looked like when becalmed?”  Of course, no marine painter would paint Cutty Sark when becalmed: They would paint her as if sailing on a broad reach, with all sails set - and with flags and burgees mostly pointing straight aft... Now, I haven’t seen any photo of a becalmed Cutty Sark, but I have seen old photos of square-riggers drying their sail in harbour, and the sails of course looked like laundry on a string.

Sooo... please stop fretting over such details, and focus on making your sails work when there is a wind...

Cheers, Arne

PS: In the beginning of June, it will be 25 years since I hoisted my blue cambered-panel sail on Malena for the first time (see NL 30). No big milestone for the world, but a fine little jubilee for me.

 

Graeme wrote:

But down wind? Oh man! - those big panels filled and pulled like a spinnaker.

The sail is robust and not lightly constructed. In the flat calm when we started out, the horizontal shelf panels sagged and the sail looked terrible.  But when a little bit of wind arrived, and the sail inflated, it started to look very good, with full camber from batten to batten. 

So, comments on the saggy sail with little wind. This is what happens with these camber panel sails. With the sail up in no wind conditions I was always slightly embarrassed by the wrinkly bag of 'Footprints' sail, but it took only a tiny amount of wind for the sail to inflate and the beautiful camber shape to develop. 

And that off wind performance with the sail pulling like a spinnaker, this is I think an advantage of a lower aspect ratio junk sail. Off the wind and downwind 'Footprints' developed an enormous amount of power and instant acceleration. I was able to take advantage of this power by canting the very large sail across the mast.

I am sure Zane will learn how to sail his new vessel to maximum advantage, enjoying both the simplicity of the junk rig, and the surprising amount of performance available with the rig,    

When I see Paul’s photo of Pango’s sail, dated 23. April, I wonder if a combination of the shelf foot method and the barrel method would make sense:

The shelf foot method looks good in the horizontal panels. However, on the two top panels, the wind is blowing more across the yard and upper battens than along them. I therefore wonder if the top panels shaped with rounded (barrel) edges would give a nicer airflow ( over a more even curve) than the shelf foot method will do. I could, of course, be wrong.

The photo below, taken this Monday, shows Ingeborg’s sail at work with one reef. The lower panels all have been measured to have 8% camber, while the top panels are much flatter, but with quite even curves (horizontally). With a SA/disp=21.5, her rig basically fills my requirements for coastal summer-cruising: Plenty of sail area for downwind-sailing in light winds, and moderate camber for close-hauled sailing.

The wrinkles along the yard and two upper battens should be removed by re-tying the sail at the luff end. I haven’t touched these ties since I rigged the sail in 2016...

Arne

PS: the slightly distorted camber is caused by the lee topping lift cutting a bit into the sail. This only happens when the sail has been reefed.

I think you are asking rather a lot, Graeme. 

Annie, I have to chime back in now and explain: you misunderstood. It was meant to be a compliment referring to Pango’s beautiful hull shape and windward potential, nothing more and certainly nothing to do with Zane’s helming which was just fine. I did say the boat sailed well on all points and Paul’s sail was a great success. (And it was a first hoist and it is a low aspect ratio sail). It was a throwaway comment, just a thought that came in my mind in a moment when I myself was on the helm – and I am not much of a helmsman, preferring to use an autopilot whenever possible. Sorry for my poor choice of words and I agree with what you posted.

Moving on…this business of entry angle… I started a new thread.

Hi,

Reading back through the posts, the only mention I see of the number 8 is of the % camber designed in, which ended up as a measured 10%.

In Slieve's McGalliard's public writings, he gives a good explanation of entry and exit angles in the section where he describes camber profiles. P56_66 will get you there. I still haven't learned how to do links, Sorry!

Well worth reading all his stuff, as well as Arne's, if you haven't already.

Lovely camber in your sail, by the way.

,