Cutting welds on 1985 Bass Tracker TX Tournament transom

[Patsway]

I am finally to the point of cutting the welds on my transom and need some advice on how to accomplish this. I have an angle grinder with a cutoff wheel but need to know how to do this. Do I cut the weld off by going diagonally across the weld cutting deeper as I go? Or do I turn the blade to go vertically into the seam of the weld making sure not to cut into the top rail of the boat itself? Both seem a little scary. I just want to cut the right way to allow the cap to pop off without damaging the boat or the cap.
Thanks for all the help so far on this project.

 

[typed by ben]

i would first use a flap wheel to grind the welds flat, then a scribe and a straight edge to locate the centerline of where you want your cut to be. then get a metabo and score your cut line into the metal. spray the score with a little wd40 to keep the blade from clogging, then score again and with each successive pass go a little deeper, but dont apply pressure with the cutoff wheel.

i would NOT just plow into it from the top- if the blade goes right in and cuts the weld on a preloaded joint, the metal may move to eat up the new opening and clamp onto the wheel, which can be very dangerous