Jester’s mast is set quite far aft. The purpose of my exercise was to find how broad a sail I could fit to that mast and still get away with 22% mast balance, and without moving the CE of the sail, compared to the original. It turned out that a batten length of B=4.0m worked fine. I knew I could then make a full-length yard at 60° fit, after adjusting the mast to upright (from 1.9° aft rake). Then it was just a question of sketching in that yard and boom in such a way that there were good enough clearance above deck and between the halyard’s slingpoint and the mast top (0.18B). This turned out to produce a sail with AR = 2.32.

Now I had actually a master sail in my ‘library’, with AR= 2.30. This was given a new top section with a yard angle 60° and with the two top panels the same area as the lower panels. No need for a special panel 3. This was then scaled to B= 4.00m and tried on Jester. The sail suited fine and came out with a sail area of 29.6sqm. Only now did I get to see that sail area.

Pango’s sail of 330sqft is 30.65sqm in real numbers.  That is only marginally bigger than the sail of my Ingeborg  -  with one reef  -  at 30.15sqm. I surely am glad for those extra five square metres in Ingeborg’s sail. With her mast reaching only 9.6m above the waterline, this is still a quite seaworthy rig, in my view.

Arne

I've always thought that Jester (1960) was woefully under-canvassed, and wondered why none of her owners or guardians ever got around to making her a new sail along the lines of what we now know as the H-M planform, that had been developed fully by  the time that Galway Blazer II was rigged (1968). I think you've got the area and AR about right, Arne, for the kind of Atlantic crossings that she was designed to make.

Stavanger, after another sunny but chilly day.

Still a bit early to go sailing here, or even for scrubbing the deck and cockpit. The sun shines invitingly every day, but when there is frost in the morning, it is wiser to wait a little. Then the TV and web is full of that terrible war. To stay half sane, I have amused myself tonight with drawing a new JR for Jester.

The idea was to see what can be done to improve Jester with a new sail, set on the original mast, and with the CE in the same fore-aft position. Even without positioning the boom very low, or making the drift for the halyard span short, the resulting H-M style sail with 60° yard ended up at 29.6sqm. Its mast balance is around 22%, after the mast has been adjusted to stay fully upright.

See for yourself.

I also let you compare Ingeborg and Jester sitting side by side (same scale). I don’t dare to bet which would be fastest when close-hauled. Downwind, my guess is that Ingeborg would take the lead in light winds, while jester would take the lead when Ingeborg needs a reef.

What do you think?

Cheers,
Arne

(se Arne's sketches section 7)

This is my dream!  The split junk rig on a modified Folkboat--I simply need to work up the cash . . . and the nerve.

David Tyler wrote:Same planform, cambered and split - OK. But please, scaled up to at least 30 sq m!

Well, yes, but I think that might require a change of planform. Jester's rig is already pretty tall for a 25 foot boat (LAP c. 30 ft. ?). Keeping the same planform and increasing sail area to 30 sq m would raise this to around 35-36 feet (although Jester possibly has a mast taller than it need be for that sail). 

Chris