Attached is a photo of my arch with a tape measure pulled out three feet for reference. I also overlayed the two photos and it doesn’t look like the arch-in-a-box sized for a cutter/sloop will work with the ketch rig.
However, another user sent me a picture of his ketch with an arch that looks like what you want. I sent you both an e-mail to put you in touch and included the photo here.
Lastly, Rich sent his solar davit solution as another option.
I actually had trouble posting these photos myself… who runs this website? 🙂
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Siren Engineering, LLC