Hi there, I live in Wellington, New Zealand where we get very few 10-15 knot days and a lot of 25-35 with big chop. I'm a low intermediate and 87kg.
I have an Axis 820 (low to mid aspect) and a 900 ((HA).
I have a lot of trouble getting the board speed to fly the 900 as the board keeps being slowed by chop.
I do my best to weave through it, try different points of sail etc but it's usually just an arm stretcher until I can get back to the beach and put the 820 on (Instant smiles).
Apart from 'find smoother water' is there a trick to getting HA foils up in rough water?
I'm still dialing in the technique on my first HA (Armie 1125). I'm finding you need to have 'light feet' when at the lower end of lift-off speed threshold. If I find the board porpoise up, instead of pushing it back down, I've had luck going with it and sucking up my knees and gliding down out of it, slowly and lightly extending my legs, using the wing for as much support as possible.
In the end it is all about board speed. Depending on the wind chop direction in relation to the wind, normally one side will be much easier to start, utilizing a bit of the chop direction for speed gains.
Go downwind more and use the wind chop to achieve liftoff. On bigger days, it is like the water dropping out from below you instead of you lifting of.
Funny I learnt on the old 820 and the 900 and in the end was always on the 900 - decent wing.
all the tips above are sound, especially heading downwind and being light on the down push by bringing your front knee up - so then you glide down and level off on the foil rather than bang it back down on the water again. also as with good starting technique push your hips forward (which pushes the board forward).
Then as you come up some relatively gentle and quick pumps to get some speed in the wing.
in the end it's all about "feel". Don't have too many variables swimming around in your head.
also if possible have the mast plate more forward when using the 900.
just takes water time man. You will get there