Actually I see another argument against stepping a junk mast in the original mast position, even if the CE could be made right: One will need a stouter mast, so the original partners will have to go. Most probably, the mast step will have to be beefed up as well. This makes it awkward to convert the boat back to original rig.

Another thing, on my dinghy Broremann I sailed for a year with the junk mast stepped in the original Bermuda rig position, which was 25cm aft of where I had designed it, and later put it. That worked in a fashion, but if I could not have moved the mast further forward, I would have replaced the flat swing-up aluminium rudder with a bigger, balanced, streamlined foil.  I see nothing wrong with “sailing on the rudder”, as long as the rudder is big and strong, and with a nice balanced and streamlined section. That was the Chinese way of doing it. One needs to fit a good tiller lock though.

Arne

PS: My Ingeborg is not a FB (Nordic Folkboat) with the mast through the deck, but an IF (Marieholm International Folkboat) with the mast stepped on the cabin top. The FB’s mainsail-to-jib ratio is higher than that of the IF, so the original mast is stepped a bit further forward.

Slieve,

In your excellent "Thoughts . . ." document, I read this regarding mast placement:

'This has the interesting effect that on some fractional rigged boats with quite small jibs the mast may end up being placed in the same position as on the Bermudan rigged boat, or maybe even further back! The drawings for the FolkBoat are particularly interesting in this respect.'

I don't see Folkboat drawings later in your article.  Did I miss them?  I'm interested to know what you discovered for mast position on the Folkboats for your split-junk, cambered panel sail form.

Steve

Paul McKay wrote:

I looked at your photo and sketch and in my opinion your mast is too far forward to benefit from a Split-Junk sail. 

That is partly what concerns me.  The rule of thumb seems to be that the mast of a split junk can go where the mast of a fractional sloop rig would be.  Mine definitely is farther forward.

Then again, I have uploaded a new picture at http://www.junkrigassociation.org/Sys/Profile/PhotoGallery?memberId=3348632.  The drawing on the right shows in black the outline of the sail in the same position relative to the mast as in the photo on the left.  The fat blue broken lines show where the sail is while sailing (possibly rotated counterclockwise by a degree or two).  That still gives me more weather helm than I like.  The yellow sail is the profile of the proposed split junk.  It seems the geometric centre might even be a little further aft than that of the present sail as I actually use it.

If I were in your position I would keep your present sail but replace all the straight battens with wishbone battens. (See February's JRA Newsletter) This will give you more drive and better upwind ability. If you keep the luff haul and move the attachment point on the yard further aft you will be able to balance the helm much more easily.

If I replace a single batten, consisting of an aluminium tube with circular cross section, by two such tubes with the same weight, I will end up with less vertical strength and stiffness.  If I match strength, I expect quite a bit more weight, unless I can find oval tubes.  It's the least amount of work, though (I think).

If I am willing to pull the sail as far back as on the photo, then I could also use the permanently curved flipping battens that worked quite nicely for Nils Myklebust.  After all, they were inspired by the Bierig Camberspar, which was invented to replace wishbone booms.  They might flip the wrong way on one tack if I need the sail as far forward as I have it now.  And I'd have to build a jig for bending the battens if I don't want to just eyeball it.

Arne Kverneland wrote:

could I suggest that you upload the photos you will show us to your member's album? 

Paul McKay is right about your mast most likely to far forward to use a split junk.  I'd just make a cambered sail. Use Arne's methods if you are making a new sail. If your existing sail is still good and has a decent amount of life left in it, you can convert it into a cambered sail using the "shelf foot" method, Split it along the batten lines and insert "lenses" that will give it the required shape.

Either method will give you improved windward and close reaching performance. Once you are past a reach of cause the performance will be pretty much the same as it is with the un-cambered sail.