mounting rudder and strut square on a mono

[Chuck E Cheese]

i have built several monos and am curious how everyone is getting the rudder and strut bracket straight on mono hulls. up until now i have just been eyeballing it in relation to the seam where the deck and hull are joined and drilling it. i have noticed on some hulls (my rico 31 mono) the deck seam isnt perfectly square but it came with tape and markings from the manufacture.
i am building a DF 29 copy and using a square to draw the center line for the strut it just looks like it inst straight (from the center of the ride pad to a tri-square on the deck seam)

how are you guys measuring and marking the trandsom?
thanks

[Team FFRB]

Square Up

I mark a line from chine to chine then use a square to mark vertical centre line.

Use centre line to mark of the rest of your hardware.

[Chuck E Cheese]

great idea... thanks