Sorry for assuming...you know what they say!

Take your trap wire and add a bit of line to it. Then swing it forward until the line hits the base of the thimble (forestay). Keep that point as a ref. point, then take that to the back of the boat. Measure where that point hits. It should hit around 20mm aft of the beam for all conditions. Keep in mind, this works for the ahpc flyer. Anybody know about the Mk series?

Hope this helps,

Michael