I know how to do it from scratch, but I don't know if I can explain it properly. I'll try...
First make your hole. Cylinder, expand, bodge out holes, fill edges.
Now you need to just make 1 section, and then link them together.
So you have a hole, now you need to turn it into a sort of watch.
Expand the strap in bendable sections, which will be the body of the tanker.
Now make a bend modifier.
Bend it all 360%
Select top faces, and flatten in the Y.
Link sections, make ends.
Or, if you really want to fix your model. Just make a cutting tool template. Just put the end of a cylinder beneath where you want the hole, and the cutting tool will lock to it.