Cetol Vs Honey Teak
There used to be a tool that attached to a drill called a portalign,it''s function was to allow a person to drill a hole perpendicular to the plane it was set on,Ideal for drilling on round surfaces. Unless you are filling all the old holes and attaching the rail somewhere other than the original spot you can mark holes from old piece and drill. Also a side note since you are pulling the old ones off, and more than likely putting them in the same place, take the time to drill a larger hole where the bolts came thru and epoxy them then redrill the proper size hole for the bolt this will also keep moisture from entering your hull.by the way you can buy an inexpensive bench type drill press or a base for your drill for less than fifty dollars. good luck with your project.