Gareth, Attached a drawing showing how to find the radius.
1) determine the length of track
2) make a cardboard jig of your actual boat curve....be accurate
3) lay the jig on a flat surface, measure the height (most likely not very much)
4) there is a math way to determine if it's a radius (too long since math ...for me). draw lines maybe 2 inches apart also an equal up.
5) if all the same.....it's a radius, if not I am sure the overall rise will NOT be much off the deck and find a "close enough" curve.
Harken or whom ever will need the length and height of rise.
That is a great explanation and it makes perfect sense, but I am thinking that measuring from the hinge of the boom to the loop for the mainsheet and then calculating the dimensions would be easier. The old track was flexible so went straight as soon as I pulled it off the deck.
It looks like I am going to have to task a machine shop with the jib track, and I am not relishing that task since getting anything done these days seems nigh on impossible, and shipping a 17'4" track to the boat will be quite a challenge, although luckily I still have the port track to copy..