Its not needed. I tried my MKI frontwing on the new mast with the 2 bolts and it works fine. Besides that, the screws are only there to secure it, the construction is taking almost all the load.
Although the new mast is noticeable stiffer as the MKI, it is for my 97kg still a bit too flexible so I stay with my Cedrus.

I wrote (In Dutch, but DeepL or Google translate work okay) an review about the 1050 with the new mast, compared with the MKI.www.facebook.com/groups/wingsurfnederland/permalink/1449476722520906/

Jeroensurf said..
Its not needed. I tried my MKI frontwing on the new mast with the 2 bolts and it works fine. Besides that, the screws are only there to secure it, the construction is taking almost all the load.
Although the new mast is noticeable stiffer as the MKI, it is for my 97kg still a bit too flexible so I stay with my Cedrus.

I wrote (In Dutch, but DeepL or Google translate work okay) an review about the 1050 with the new mast, compared with the MKI.www.facebook.com/groups/wingsurfnederland/permalink/1449476722520906/

Please take my disagreement without offence. Your statement is exactly why the cross bolt perpendicular and in between the other two bolts is needed. The mast is noticeably stiffer and yet the foil underneath appears to be flexible in your own words. The leverage on the mast fuselage joint is massive when under load. Yes the two bolts will work fine...to a point. However, when that 'point' is reached the joint will flex open incrementally and 'flex'. The cross bolt would come into play at this moment, inhibiting further flex and 'opening' of the joint. I hope this makes sense without causing insult.

Hi @jeroensurf
Super thanks for this review and the one on FB (the translation works well enough). I was thinking of going for a Cabrinha as my surf foil. But I'm not sure now....

I feel for the designers, they are never going to please everyone with rider weight, skill and conditions so variable. Jumped back on the 19mm Axis mast yesterday and could feel the extra drag at speed compared to the Cabrinha hollow. It wasn't an issue just cruising around but every little bit counts when you're chasing a wave down, cranking up for a big jump or taking a big drop.

The side bolt definitely improves the joint stiffness and will help with keeping it tight over time but if your mast to fuse join is already tight then you won't notice a difference. Carbon is soft and wears down over time, I use to give the old mast inserts a couple of coats of epoxy when play crept in but with the clamping effect of the side bolt I haven't had an issue.

If I were going to do this I would put a hole in 2 12" long pieces of plastic or cardstock, and aggressively tape them to the side of the mast far enough up and tight enough that the position won't shift, with the holes over the mast screw holes. This should allow precise hole positioning when you put the fuse on. Assemble the bottom section onto the mast and use those holes as your drill/layout guide.

I cracked a gen 1 fuse and cut it apart and there's nothing inside of the fuse that would prevent this from working or anything critical that would be compromised by this mod.