Chris
I recently fitted a Tuff Luff to my GK during the winter season, albeit a fractional rig.
No great probs, but dont believe the "fit it in 10 minutes" waffle quoted. Muchos cursing and swearing as it "easily and efficiently" wouldnt snap together over the forestay !!!
The foil comes as a roll so its easy enough to measure by hoisting a tape measure using a genoa halyard, and adding on a couple of feet. as I recall the extra couple of feet aint too expensive, but the whole kit was a shade over the ?400
Best advice is read, and re-read the instructions, and then have some-one else re-read them. They are vague and it ever so easy to fit the bloody foil upside down and only find out when the lower die-cast feeder wont fit!!! :
Whole lots was supplied by Coates Marine, but dont let them fob you off with "doesent need a pre-feeder". I re-conuted this statement to the fore deck crew who after having completed the first lap told me I was speaking out of my fundamental. Its a swine without it, and the genoa jams unless the feeder is fitted and adjusted accordingly.
best of luck, and money well spent from our point of view.