I have been following this thread with great interest, as it has drawn out a lot of very good information and much food for thought, from our experienced commentators.

One rather crucial point seems to have been a little glossed over, and that is, choice of mast length. It seems that Scott has chosen Arne’s planform over other alternatives on offer, partly for the reason that it is important to him to keep mast length as low as possible. This is a question that I think would be of interest to anyone designing a new conversion and I would be grateful if it could be re-visited. So as not to distract from the current discussion which is ongoing in this thread, I have started a new one in the hopes of focusing on mast length.

Scott, the battens on Brenda B are 11 ft.  The long one is probably about 12ft.. They all are 1 inch X .65in., 6061 T6. While the longer batten might have been one size up is has been fine over these past three sailing seasons.  While displacements are close, your boat is a a foot beamier, and at 22 ft is likely to carry more weight than my 19 footer. I think 1 1/4 inch  X .065 inch would give more stiffness and less weight than the 1 inch x .125.   I wouldn’t consider pipe. Strength to weight is most often much too low compared to tubing. I’d stick with 6061 T6 for it’s strength. It seems that 6061 T6 and 6063 are the most easily available grades of tubing in the US. 

For me figuring the yard was more of a challenge. I end up with 2” x.125 tubing, same grade. I screwed up my order for  2x.065. I’d planned to laminate a 1“ tube to the lighter 2 in. similar to what was done and shown elsewhere here. The single .125 tube is a bit heavier up high than I wanted but I was suprised to calculate that it was not by all that much. 

https://www.onlinemetals.com/merchant.cfm?id=71&step=2&top_cat=60 

This site lists tubing weights by size, inches and lbs., and should be helpful in making comparisons.

Arne,

At a 70% increase in cost and 82% increase in weight I can get 1" OD x .125" wall.

I have been looking here and here. I hope to make a stock 12' length work for all battens except the top sheeted batten. For the 'long' batten I would buy a single 20' or 24' length and cut it down.

Maybe the 6061-T6 0.840" OD x 0.109" ID (OD 21.336mm x wall 2.7686mm) T312 is a better option. Smaller OD but thicker wall?

To keep my project going I will need to make a decision on battens. I have come full circle and now I am thinking alloy battens again.

Arne was kind enough to suggest that I look for 25mm OD and 21mm ID AL alloy (25x2mm).

Considering the price and weight I would like to use 6061-T6 with a 1" OD and a wall thickness of 0.065". If I did the math right this works out to a 25.4mm OD and 22.1mm ID. This is a slightly larger OD but with thinner wall compared to what Arne suggested.

I think this is the same size used on 'Brenda B'. The listed displacement I found for my S2 6.7 is 2200lbs and the Com-Pac 19 is 2000lbs. Pretty close. But on the other hand my battens will be longer than the ones that 'Brenda B' carries.

Does anyone have reason to expect 6061-T6 with a 1" OD and a wall thickness of 0.065" is not strong enough for my rig?

Panels Seven, Six, Five and Four stitched together. Is the luff straight enough? I don't worry. I'm happy.

More photos in my album here.