J/30 Class Association Forums J/30 Forum One Design Class Rules Mast Step Postion

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.

I had my mast re-stepped on Friday as my mast was quite far aft from the 25mm standard. The screws did not come undone after reasonable effort with an impact driver, so the rigger simply drilled them out and cut them flush. New holes were drilled and tapped in the proper position. Everything was remeasured and tensioned using the North Sails guide. Looking forward to tonight's race to see if I can point a little better now.

I am going to do this on Naples Vee Jay next month ... let us know if you notice anything ... but it also involves restoring length of forestay to OD length [longer] ... and that may or may not click with current sail length ... also top of mast further back allows better clearance with the back stay ...

I have harken roller furling which is almost 3 in. shorter than OD forestay length, but enough adjustment to go OD length.

Well, last night it blew 16-18 kts and we put up the 140% cruising sail instead of the racing No1 but we were handily outpointing the Hotfoot 30 who had a blade up. Granted I was pinching a little to try and keep the boat flat, and my cruising sail is quite bagged out, but we were still doing 6+ kts upwind. We improved our regular finishing spot despite a less than average start for a respectable 4th position. Boats we beat all have longer waterlines (Hotfoot 30, Spencer 34, Crown 34, Santana 30/30, Wylie 34) which feels good because of the wavy conditions we get with bigger winds. The big winds also allowed us to hold off the competition downwind as the increased pressure allowed us to sail deeper angles. The 34 footers I race against are all mast head rigs and sail straight downwind almost all the time. The gain on the fleet was achieved entirely on the first beat. One issue is that we will likely have to shorten the backstay a little. It took quite a bit of travel before things started to have an effect. A promising start to the new rig tune. Hopefully better results will be coming with our regular 8-10 kts westerly where we can use our proper No1.

The position of the mast step has an enormous impact on rig tune. 1" of movement forward at the step (assuming the partners are the fulcrum) translates to ~8 1/2" further aft at the top of the shrouds (when the rig is not tensioned). All the tuning guide settings assume the step is in the proper position. If the step is too far aft, the rig will not have nearly enough rake and will have too much prebend when tensioned. I have firsthand knowledge of this-my step was in the wrong place for the first several years that I owned Blue Meanie. Fixing it made a HUGE difference!

Steve, that's what I'm hoping for! We'll see next week.

ditto ... only next month on naples Vee Jay which is moving most of an inch. Why they ever came "random" from the factory is yet to be explained.