I am a little bit mystified by the description of your proposed rig.

" I have decided to go with an Aero-Junk Rig (flat panels, rigid continuous battens with a fixed jiblet) to balance good windward performance with bulletproof mechanical simplicity."

Rigid continuous battens? My understanding of the aerojunk rig is that it has flat panels (main and jib) which take on some camber within the confines of double wishbone battens. I have seen three such rigs in New Zealand (the best-known being Pete Hill's Oryx). I think the first to develop this rig is Paul McKay and here is a photo of his Miranda with aerojunk rig.

Paul doesn't seem to follow this forum, but you can contact him via the membership list in the Members' Area of this website. He would be the go-to person for the Aerojunk rig.

("Rigid continuous battens" seems to suggest SJR (split junk rig), but building a SJR with flat panels would be a hopeless idea, and the virtue (or otherwise) of cambered SJR will depend entirely on the amount of balance relative to the mast, of the sail in question, which is as yet unknown). 

(Another couple of confusing points - what is a "cascading" sheet system? What is the distance between the two masts? Where is bulkhead 2.5? Building a two-mast rig around that existing mainmast position might turn out to be a bit of a challenge).

I think the best advice would be to see if a plain, two-sail, junk rig outline can be drawn up on those mast positions you have chosen, with a combined CoE which matches the CoE of your original sail plan - and leave the question of type of junk rig until you have done that. You might also want to consider if you can be flexible about mast positions. I have doubts if a ketch rig can be built around that mainmast position, although a schooner just might.

But these are just geometric considerations. I am not a designer of rigs. I just put these discussion points and hope to bring your project back into general discussion.

One more thing: Here is a lengthy thread on a similar situation to yours, a 12m vessel where the owner wanted to build the rig around the original mainmast position. It has turned out to be possible (I think) and the project is now near to competion. One of the problems, in the end, was to get enough distance between the sails for a workable sheeting system. He may yet need to use port and starboard sheeting on the fore sail (not sure yet) which is a plan b, not a first choice. Have a look: https://www.junkrigassociation.org/technical_forum/13545697

Hi everyone,

I am currently refitting a Reinke 12m steel yacht and converting it into a freestanding Junk-Ketch. I am a shipwright and welder, doing all the metalwork myself. I have decided to go with an Aero-Junk Rig (flat panels, rigid continuous battens with a fixed jiblet) to balance good windward performance with bulletproof mechanical simplicity.

I plan to sew the sails myself using WeatherMax 80 fabric. For this, I am looking for a designer or a skilled community member who could calculate the balances and draw the sail plans/panel layouts (CAD/Excel template) for me.

Here are the technical specifications of the project:

• Vessel: Reinke 12m (Steel hull, heavy displacement).

• Displacement / Draft: Target displacement is around 18 to 20 tons, with a draft of 135 to 145 cm.

• Target Sail Area: Approx. 120 m² total (75 m² Main / 45 m² Mizzen).

• Masts: Freestanding S355 industrial steel tapered poles. Mounted in heavy 10mm steel tabernacles/sleeves with 10mm POM lining.

• Fore Mast (Main): Total length above deck is 13.5 meters. Location is at the very front (stepped at bulkhead 12.5).

• Aft Mast (Mizzen): Total length measured from the top down is 11.2 meters. Location is midships (reusing the original mast step position around bulkhead 6.5/7).

• Distance between Masts: [Hier den genauen Abstand in Metern eintragen] meters.

• Sheet Lead: Cascading sheet system.

Additional Note on Balance & Hydrostatics: Since the main mast is stepped very far forward at bulkhead 12.5 and the mizzen sits midships around bulkhead 6.5/7, the center of effort (CE) will shift significantly forward compared to the original Reinke 12m lateral resistance (CLR). Given the heavy displacement of 18–20 tons, getting the balance right is crucial. To counteract potential lee helm, the main sail's balance (jiblet percentage) might need to be kept on the conservative side (e.g., around 18–20%), or the sail geometry should extend as far aft as possible. I would highly appreciate the designer's input on optimizing this balance.

What I need: Since I am using WeatherMax 80 (usually around 150cm roll width), I need a flat-cut panel layout that minimizes waste and gives me the exact geometry for the battens, yard, and boom, including the correct aerodynamic balance (the percentage of the sail area/jiblet in front of the mast).

If anyone has a matching template, is willing to scale an existing design, or offers professional design services for this specific configuration, please let me know!

Thanks a lot and fair winds,

Bernhard