How often do kite lines typically last? I've been kitesurfing a few years now, with the same equipment the whole time, and yesterday two of my lines snapped simultaneously in one horrible gust. I had just self landed and attached my chicken loop to a post, so the kite and lines bore the full force of the gust with zero give.

BoM indicated gusting to 30 knots at the time, but gusts as you know can be 40% higher. Just curious.

Really important point this.

A lot depends on where you are kiting and how you look after your gear and what actually broke. I can see that it looks like it was more of a joint of spectra and a sheath rather than just a line pure?? I find often when I have seen broken lines over the years that its more like what you have shown, I think because of stitching, wear pulling on one point, back and forth or twisting wear, grit and sand in the joins or inside the sheath or just its a weaker point on the kite line or bar / hardware etc. Spectra (I just mean the actual line not the ropey or other joins etc.) does break of course and I agree with Mick that the 3rd and 4th year is pretty old. but I have mates with older gear that keeps on going. If you are on rocky spots, drag lines over rocks, you have an apparently incident free event like dropping kite and it gets pulled over something, reef rocks and all seems good? those events will weaken the lines.

go over them regularly and check for fluffy bits and wear, keep them washed and dry and look very hard over the joins and the non pure line sections, the bits where they join into your hardware where wear and tear is much more common.

Oh and check when you set up that perhaps a line is not set up perfectly, like a kite bridle and something is crossed over, or a pulley and is stuck or twisted. remember that we are pilots and should treat each kite like checking an aeroplane. set your gear up so these little twists and knots don't happen.

Daz