Dont be afraid to add a spin to your A. disagree with those saying you have to stiffen the mast. 2x A worldchampion Bunkenburg (~85 kg) as well as myself were using F18 kites in up to 20 knots of wind. He used a saarberg mast while I used marstroem masts without problem. don't advice 21 m² so... in this case less is more! as soon you want to sail competitive against other boats and the course is not a triangle ur up+down, its more important to be able to run the same angles as the others. I was constantly running about 10° lower than F18 and co. The result was that in a lot of long distance races I couldn't use my kite while others could. Two main problems have to be solved: you need a kind of crossbar to prevent that the siteforces generated by the spi pulls the hulls together. A's are sensitive to windage, so snuffer, lines, bars will cost you deeply upwind speed and angle if not designed with care. Best concept how to support your spipole is shown with the marstroem M20 and M18 (widened A-cat with spi) using carbon tubes (masts for rc modelboats) to support the pole while dealing with compression forces same time. I would recommend an F16 spi for the A: the luff lenght is quite short (so you don't have to mount the spi halyard block to high) and the shapes are pretty flat nowadays. ask AHPC for a 2nd hand spis. you could even consider the AHPC (former Boyer/Fibrecraft) alu-tube snuffer, although it will be not the most less windage one, but its quite cheap and works well.
a marstroem A would suit your weight fine and construction quality is probably the best available. 2nd choice would be mk5 or AHPC flyer.
