I've pasted your questions in here and will answer them one at a time.
How would you recommend to tune my FT 148 for overpowered conditions and serious chop?
I'd recommend that you get a smaller fin, moved the mast foot back to free the board up, and use a rig that well powered, but not overpowered.
If you use a rig that's truly overpowered, you will get lifted and perhaps slammed and after one of these "yard sails" you will be so tentative about using the power you have available that you'll probably not sheet in enough to get good power and mast foot pressure.
Where do I move the mastfoot? [with 7.5 sail]
Like all sail sizes, keep moving it back until you have tailwalking type control issues, then move it back forward incrementally (2 cm at a time) until you just have a level of control that kinda scares you, but you can handle things without crashing.
This frees your board up to go it's fastest and allows it to cruise over the chop rather than slamming into it. Also, since you aren't racing, head off to take the chop at a better angle when ever you can. Chop coming in at about 45 deg. off the upwind bow just begs to be "hopped".
What about the straps - right now I have them in the middle position but I'm starting to think to move them more outwards to get better upwind performance - but will it make the board more difficult to sail in rougher conditions?
I am very surprised here............... I would have thought you had moved the footstraps all the way back and all the way outboard a very long time ago.
So, if you haven't moved them outboard and back all the way, what prevents you from doing so......?
What do you think is going to happen if you move the footstraps all the way back and outboard?
I'd really like to hear your answer on this. It's kinda pivotal to your progress.
What will happen with the footstraps all the way back and all the way outboard.....
my guess is that you will go faster and have significantly better control (better leverage to control fin attitude) than you can imagine is possible.
I am 90kg, my smallest sail is 7.5 Gaastra GTX (I know how to tune it down).
I know it's not a board for this kind of conditions and I'm looking to get a used Carve 122. My major problem is chop and I'm not really into tricks/etc. I just want to cut through the chop and have a smooth, controlled and fast ride as I have on easier days with my FT. Do you think Carve 122 will be a good choice (too large possibly)? Maybe a different board?
The largest sail I'd like to use it with would be 7.5.
Carve 122, Isonic 122, or Futura 122 would be excellent. If you want to "stretch" a little more, the 111 liter versions of all of these boards might be even better.
I'm also planing to get a 6.0 GTX (also 3 cams as I really like my 7.5) and then 5.5 Gaastra Remedy - does that sound like a reasonable plan?
Why 3 cambers in a 6.0 m2 sail?
Sounds like an OK plan, I'm just not sure what the cambers get you in sails smaller than 7.5 m2. Don't get me wrong, I have a set of small 3 and cam sails, but I only use them in certain conditions. The rest of the time I use Retros and Huckers and I go pretty darn fast.
Going upwind on Carve vs. FT.
I like working on my upwind techniques on my FT (like lifting the windward rail with my front foot and pressing across the fin with my back foot) and usually I'm slightly better then people on typical freeride gear, but I feel I'm still not quite there, especially comparing to the local formula folks (but I'm not sure what difference should I expect between formula and FT in upwind performance). I want to be unbeatable in terms of upwind ground!
So, what fin do you have on your FT-148 now, the stock Drake 56 cm?
An upgrade to around 62-65 cm would help with early planing and perhaps get you some better upwind performance, but going to a 70 cm is not going to get your FT-148 to have the upwind performance of a full on formula board.
Do you think buying a 70cm fin for my FT to be used with 10.0 sail makes sense? What kind of fin?
The big Drake Race fins are pretty good. Gorge Fin Co. and True Ames have some really
good race designs as well.
How about going upwind with Carve - what kind of technique will it require and generally, how does this board will feel comparing to my FT?
The Carve is not going to go upwind anywhere near as well as the FT-148.
Why....? It's a slalom board, with a much smaller fin. It will be faster and easier to control in chop than your FT-148, won't plane nearly as early, but it's whole concept is very different from the F-Type.
Thanks and I can't wait your answers,
OK, you've got some answers, now let's discuss them a bit.