Don ... it appears that geometrically unless we are at 25 mm setback and solid back at partners ... we will be unable to reach target headstay length ... and have anywhere near enough tension to hold up a RF to work well. You should be just able to do it, considering that -1/8 in. probably is good to kick up forestay tension for a heavier foil. There is only so much tension we can use to pull the mast back with the uppers ... I don't like going over 35s.

Tomorrow we will be resetting #505's forestay as I just didn't realize how critical that mast step measurement is in limiting the adjustablity of the forestay.

I will measure what the forestay with a RF >>>HAS TO BE to look right for a 40mm setback and post.
We are in middle of season here and I am not up to pulling mast to reset this year.

Photo of mast full aft in partners:
[we use cedar shingles wrapped with shrink tape to lock mast position.
Same, same close to 11'6" locked back trying to measure over deck stuff.]

OK ... after several hours of readjusting with the help of Brian, J30 #22, we are running 35' 7+" forestay with the mast base set back at 40 mm, which we are not going to be able to change until the next time we pull the mast. At which point we will move it to the Min at 25mm. With no backstay on we are looking initially at a pretty straight mast with very little pre bend, basically to see how much bend we can generate with heavy backstay over 15 kts.

We will be working with this setup this weekend on the water, but unfortunately will not be able to tune up against another boat until the regatta the end of the month.

for the purposes of discussion I can't see how we can consider setting the mast step as "tuning" of the rig, but instead consider it bringing the mast into the necessary configuration for racing or maximum accepted performance.

1. If you ask a sail maker to build a J30 #1 they automatically assume headstay is 35' 10.5" because that is what the max head stay is supposed to be, and that gives the biggest sail. So by ordering a standard J30 #1 or even a 155 they expect you to be set up Max. If you are moving sails from one boat to another ... this needs to be the same.

2. to achieve that forestay length the mast step needs to be at 25mm ... there is only so much you can do to bend the mast where it don't want to be bent. So that has to be set at Min. to move the mast at the fractional back enough to get OK tension on the forestay at the target forestay length.

Back in January I solicited guidance on how to get the screws loosened on my mast step.
I'm pleased to report that after a winter of soaking the screws in WD-40, and with the combination of an impact driver, a 5 lb sledge, a propane torch and a 2 x 4, the screws loosened sufficient for me to beat on the step with the 2x4 and move the mast step back the required 1/8". The step is now OD compliant!

Thanks to all for your suggestions

I tried getting mine loose yesterday with an impact driver with no success. I am 1" too far aft, although the boat seems to go like stink upwind still.

Will beat on it again tonight.