dieseagull said..
Ok thanks again everyone for the advice, I really appreciate the perspectives!
I've tried to synthesise recommendations varying from max volume = weight + board + foil, to bodyweight + 10, to just bodyweight (from my shop).
I've decided to pull the trigger on a 90L Super K 2. Rationale being:
1) I'm currently losing a bit of weight to get back to an ideal of about 86-ish kgs.
2) 86 kgs + board + foil = just over 90, complying with all advice except the over-sizing advice.
3) Wanting to avoid corkiness that might come from oversizing.
4) More motivation to continue dropping the kgs (not that I've really been struggling, but everything helps).
5) Kinda want a 1 board quiver.
Hopefully I'll be able to provide an update when the board arrives November-ish on whether it's awesome or whether I've made a huge mistake!
After many months of patient waiting I finally got my 90L Super K 2 and have had a chance to use it twice for a total of about 80km on foil. Both times in powered (or overpowered) conditions, so no chance to try it in light conditions yet. And only used it in moderate chop - both times the wind was cross offshore so it was relatively flat.
But oh my god what a (sorry but I'm going to use that word) gamechanger! Everything is a direct improvement/upgrade compared to my old board except stability on the water, so I'll cover that first.
Stability on the water was the part I was most nervous about: would I actually be able to use the board or would I fall off every time I got to my knees? It's below neutral for my 90 kgs + gear, but it isn't too unstable on the water, and actually some things are better. It's less stable than my learner board, particularly in roll, but it's more stable in pitch (front to back) so as other people have said, as a beginner/intermediate changing from a learner board you definitely notice
more stability front to back and only have to worry about side to side. Old board sometimes (especially in chop) felt like trying to balance in all 4 directions, but this one you primarily just worry about roll, and when standing with the wing powered that's easy. Another benefit is because the board is narrower, I can hold the wing in the water by the front handle with the strut parallel to the board, and my front hand is only slightly off to the side, as opposed to the older wider board where the front hand was far enough offset that I had to lean a bit for it, which reduced stability.
Once on your feet it's only upside. The board builds speed while in the water in a way that feels amazing. The hull speed of the board is easily higher than the stall speed of my big foil, so the board transitions directly from displacement to flying. Because of the much reduced drag, hitting chop etc (or touching down) doesn't result in as much deceleration, which used to make me go over the front. This board just cuts through with almost no deceleration. Touchdowns are no big deal for the same reason, and the board feels much less sticky when it does touch the water. Due to the narrower width and rail shape, I'm also less likely to catch an edge, and when that happens it's easier to recover as well.
Lastly, something that I really didn't expect, but the board feels more reactive when on foil. Maybe I should have expected this as it's a bit lighter and narrower (so not as affected by wind?) but I feel like I can feel the foil better. I also feel over-corrections are more likely due to the reactivity which maybe isn't ideal for a beginner, but for me it's no problem and I haven't crashed because of it.
Keen to get more km on it and particularly to try it in light wind, but so far this board has been a massive upgrade and I'm very happy I pulled the trigger.
I was a bit nervous about the narrower board, because I'd often struggled in bigger chop and high wind on my learner board, and because of reviews where people had said things like how the Super K 2 is on the narrower/less stable end of the midlength spectrum, but for anyone who is a high-ish beginner (say maybe someone who is able to make their gybes 20-30% of the time and improving, and is able to do a bit of toeside riding), I feel like it wouldn't be too early to get a midlength.